Analysis and selection of a MEMS, multi-constellation GNSS receiver for a femtosatellite
Abstract
Context: The expansion of space applications and their liberalization is an actual fact since the last decade. Small satellites are developed either by academic institutions and private companies. The concept of femtosatelites, featuring a mass lower than a hundred grams, emerges from the need of deploying extensive constellations in order to get results as accurate as possible at the same time, while keeping low budgets, affordable to small research teams. Our femtosatellite,AtmoSwarm, is aimed to measure the thermospheric density as a function of the altitude and thickness of the layer. This layer of the atmosphere is nowadays barely studied, however, it is important, for instance, regarding the Sun-Earth relation or the re-entry trajectory of celestial bodies into the Earth. Aims: Positioning is vital for the success of our mission and the validation of the data obtained. This work is aimed at finding the most suitable Global Navigation Space System (GNSS) receiver in the market, following different operational requirements and specifications. Methodology: We apply a mathematical method based on a matrix decision, which allows us to shortlist the four models which better meet our mission requirements. In doing so, we have firstly carried out an extensive legal study of export regulations and operational limitations, such as COCOM, in order to be prepared to thoroughly explore actual GNSS receiver options in the existing market. During the selection process we have contacted the companies responsible for the GNSS receivers manufacture and distribution, obtaining feedback from both engineers and sales representatives. The information obtained was applied to develop a decision matrix and to obtain the corresponding Figures of Merit. Ultimately, this work was done in order to quantify and objectify the decision process, being able to adjust this method to a wide range of situations and requirements. Results: The method used proved efficient in optimizing the decision process. It allowed us to rank models according to their specifications and our mission requirements and, specially, highlight four models among the initial set of candidate options. Our model has also proved its adaptability to other components or bigger satellites with different operational needs. In our specific case for the GNSS receiver, it can also be modified in the future as market evolves, either by adding more options or by modifying the influence of each parameter in the final decision.
Full text
TREBALL DE FI DE GRAU TFG TITLE: A GNSS Receiver for Femtosatellite Operations DEGREE: Grau en Enginyeria de Sistemes Aeroespacials AUTHOR: Alejandro Guerra Mentruit ADVISORS: Pilar Gil Pons Jordi Guti´ errez Cabello DATE: February 7, 2020
T´ıtulo: Un receptor GNSS per Operacions amb Femtosat` el·lits Autor: Alejandro Guerra Mentruit Directores: Pilar Gil Pons Jordi Guti´ errez Cabello Fecha: 7 de febrero de 2020 Resumen Contexto: La liberalizaci´ on de la industria espacial y sus aplicaciones se ha convertido en un hecho real durante la ´ ultima d´ ecada. Compa˜ n´ ıas e instituciones se han puesto manos a la obra con el desarrollo de constelaciones de sat´ elites con fines acad´ emicos y comerciales. El concepto de femtosatellite, destacando su masa inferior a cien gramos, emerge de la necesidad de constituir constelaciones con un gran n´ umero de sat´ elites –con el objetivo de mejorar la precisi´ on de la informaci´ on obtenida por estos– al mismo tiempo que se mantiene un presupuesto asequible, al alcance de equipos de investigaci´ on convencionales. Nuestro femtosat´ elite, llamado AtmoSwarm, nace con el objetivo de medir la densidad de la termosfera en funci´ on de la altitud y el grueso de dicha capa. Objetivos: El posicionamiento de nuestros sat´ elites es vital para el buen desarrollo de la misi´ on as´ ı como para la correcta validaci´ on de la informaci´ on obtenida. El objetivo de este proyecto se basa en encontrar el receptor GNSS que mejor se ajuste a nuestra misi´ on, teniendo en cuenta las necesidades de la misma. Metodolog´ ıa: En esta tesis haremos uso de m´ etodos matem´ aticos basados en matrices de decisi´ on, lo que nos permitir´ a listar aquellos modelos que cumplan mejor con nuestros requerimientos. Para ello, primero hemos llevado a cabo un estudio legal sobre regulaciones de exportaci´ on, en concreto las del tipo COCOM (Coordinating Committee for Multilateral Export Controls, por sus siglas en ingl´ es), con el objeto de poseer el conocimiento suficiente para explorar diferentes opciones de receptores GNSS disponibles en el mercado. Durante el proceso de selecci´ on hemos contactado con las empresas encargadas de la fabricaci´ on y distribuci´ on de dichos aparatos, donde hemos tenido la oportunidad de mantener reuniones tanto con ingenieros como representantes de ventas. La informaci´ on obtenida en estos encuentros se ha volcado en las matrices, para acabar obteniendo una Figure of Merit. Asimismo, este trabajo se ha llevado a cabo con el fin de poder cuantificar y cualificar cualquier proceso de decisi´ on, teniendo la posibilidad de exportar dicho modelo as´ ı como su modificacion para un amplio n´ umero de situaciones y necesidades. Resultados: Nuestra metodolog´ ıa ha demostrado una eficiente optimizaci´ on en un proceso de decisi´ on. Nos ha permitido listar modelos de acuerdo a sus especificaciones y, especialmente, destacar aquellos que mejor se ajustan a nuestra misi´ on dentro de una amplia variedad de opciones. El modelo ha conseguido probar su capacidad de adaptarse tanto a otros componentes como a sat´ elites de mayor tama˜ no con otros requerimientos operacionales. En nuestro caso espec´ ıfico para el receptor GNSS, el sistema usado puede ser modificado de acuerdo al desarrollo de futuras alternativas en el mercado, ya sea a˜ nadiendo m´ as par´ ametros o modificando la influencia de cada uno de estos en nuestra decisi´ on final.
Title: A GNSS Receiver for Femtosatellite Operations Author: Alejandro Guerra Mentruit Advisors: Pilar Gil Pons Jordi Guti´ errez Cabello Date: February 7, 2020 Overview Context: The expansion of space applications and their liberalization is an actual fact since the last decade. Small satellites are developed either by academic institutions and private companies. The concept of femtosatelites, featuring a mass lower than a hundred grams, emerges from the need of deploying extensive constellations in order to get results as accurate as possible at the same time, while keeping low budgets, affordable to small research teams. Our femtosatellite,AtmoSwarm, is aimed to measure the thermospheric density as a function of the altitude and thickness of the layer. This layer of the atmosphere is nowadays barely studied, however, it is important, for instance, regarding the Sun-Earth relation or the re-entry trajectory of celestial bodies into the Earth. Aims: Positioning is vital for the success of our mission and the validation of the data obtained. This work is aimed at finding the most suitable Global Navigation Space System (GNSS) receiver in the market, following different operational requirements and specifications. Methodology: We apply a mathematical method based on a matrix decision, which allows us to shortlist the four models which better meet our mission requirements. In doing so, we have firstly carried out an extensive legal study of export regulations and operational limitations, such as COCOM, in order to be prepared to thoroughly explore actual GNSS receiver options in the existing market. During the selection process we have contacted the companies responsible for the GNSS receivers manufacture and distribution, obtaining feedback from both engineers and sales representatives. The information obtained was applied to develop a decision matrix and to obtain the corresponding Figures of Merit. Ultimately, this work was done in order to quantify and objectify the decision process, being able to adjust this method to a wide range of situations and requirements. Results: The method used proved efficient in optimizing the decision process. It allowed us to rank models according to their specifications and our mission requirements and, specially, highlight four models among the initial set of candidate options. Our model has also proved its adaptability to other components or bigger satellites with different operational needs. In our specific case for the GNSS receiver, it can also be modified in the future as market evolves, either by adding more options or by modifying the influence of each parameter in the final decision.
CONTENTS Acknowledgements ............................... 1 CHAPTER 1. Introduction ........................... 1 1.1. Thermosphere .................................. 1 1.2. Femtosat / CubeSat ............................... 2 1.3. GNSS Role .................................... 3 1.4. MEMS Technology ............................... 4 1.5. Thesis Structure ................................ 5 CHAPTER 2. Uses of Femtosatellites ................... 7 2.1. Current Research ................................ 7 2.2. A Brief Introduction to our Femtosatellite . . . . . . . . . . . . . . . . . . 11 2.3. GNSS Restrictions ............................... 13 CHAPTER 3. COCOM Legal Conditions . . . . . . . . . . . . . . . . . . 15 3.1. A Brief Introduction to the Coordinating Committee (CoCom) . . . . . . . 15 3.2. CoCom Operational Network . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.3. The Wassenaar Arrangement ......................... 20 3.4. Current Situation with CoCom Regulations and GNSS Receivers . . . . . 20 CHAPTER 4. Available Options ....................... 25 4.1. GNSS Devices Selection Considerations ................... 25 4.2. Space-Qualified GNSS Receivers ....................... 25 CHAPTER 5. Figure of Merit ......................... 35 5.1. An Overview of the Decision Matrix . . . . . . . . . . . . . . . . . . . . . . 35 5.2. Step 1: Selection of Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.2.1. Useful Parameters to Determine the Figure of Merit . . . . . . . . . 36 5.2.2. Data Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 5.3. Step 2: Data Collection and Approximations ................. 38 5.4. Step 3: Data Ratings .............................. 38 5.4.1. Collection of Normalized Data . . . . . . . . . . . . . . . . . . . . . 43 5.5. Step 4: Weight and Rank of Criteria . . . . . . . . . . . . . . . . . . . . . . 43 5.6. Step 5: Results ................................. 44 5.7. Price and Availability .............................. 44 5.8. Discussion ................................... 48 CHAPTER 6. Conclusions and Future Work ............... 53 6.1. Conclusions ................................... 53 6.2. Lines of Future Work and Development . . . . . . . . . . . . . . . . . . . . 54 Bibliography .................................... 55 APPENDIX A. Terrestrial-Use GNSS Receivers . . . . . . . . . . . . . 59 APPENDIX B. GNSS Datasheets ....................... 61 APPENDIX C. Venus 838FLPx Receiver Simulations . . . . . . . . . 63 APPENDIX D. OEM719L Budget and COCOM End-Use Statement 67
LIST OF FIGURES 1.1 1U CubeSat Platform (Image: ISIS Space) . . . . . . . . . . . . . . . . . . . . . . 2 1.2 Advanced Navigation Spatial (Image: Geo-matching) . . . . . . . . . . . . . . . . . 4 2.1 An Image of the Peruvian Femtosat PUCP-SAT-1 (Image: AMSAT UK) . . . . . . . . 7 2.2 A sample of West Ford Program needles (Image: Arcane Radio Trivia) . . . . . . . . 8 2.3 An actual picture of the Payload bay Orbital Debris Radar Calibration System (ODERACS) taken from the Space Shuttle (Image: US National Archives) . . . . . . . . . . 9 2.4 RyeFemSat Scheme (Image: Ryerson University) . . . . . . . . . . . . . . . . . . 10 2.5 PCBSat Front View (Image: ResearchGate) . . . . . . . . . . . . . . . . . . . . . 11 2.6 3D Model of our Femtosat’s Interior Components (Image: Carlos Lled´ o) . . . . . . . . 11 2.7 3D Model of our Femtosat’s (without the spherical cover), including the Stabilisation Ballasts (Image: Carlos Lled´ o) . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.1 A Scheme of GNSS receiver-missile communications (COOKING IDEAS) . . . . . . 21 4.1 GNSS 200 Series Navigation Receiver (HYPERION TECHNOLOGIES) . . . . . . . . 27 4.2 Venus838FLPx Navigation Receiver (ALTIFORCE) . . . . . . . . . . . . . . . . . . 28 4.3 Venus838FLPx Navigation Receiver (ALTIFORCE) . . . . . . . . . . . . . . . . . . 28 4.4 WARPSPACE GPS Receiver (SATSEARCH) . . . . . . . . . . . . . . . . . . . . . 29 4.5 Phoenix GPS Receiver (Image: DLR) . . . . . . . . . . . . . . . . . . . . . . . . 29 4.6 SGR-LIGO Navigation Receiver (SATSEARCH) . . . . . . . . . . . . . . . . . . . 30 4.7 SGR-05P Navigation Receiver (SATSEARCH) . . . . . . . . . . . . . . . . . . . . 31 4.8 OEM719 Navigation Receiver (NOVATEL) . . . . . . . . . . . . . . . . . . . . . . 31 4.9 GPSRM1 Navigation Receiver (PUMPKIN SPACE) . . . . . . . . . . . . . . . . . . 32 4.10NGPS-01-422 and CubeSat GPS Receivers (SATSEARCH) . . . . . . . . . . . . . 32 4.11Dual Channel GPS Receiver (SATSEARCH) . . . . . . . . . . . . . . . . . . . . . 33 4.12GPS-601 Satellite GNSS Receiver (SPACEQUEST) . . . . . . . . . . . . . . . . . 33 5.1 Data availability information for the considered GNSS receivers. Available and nonavailable information are shown in green and red respectively. . . . . . . . . . . . . 37 5.2 Datasheet Information and Approximations. . . . . . . . . . . . . . . . . . . . . . 38 5.3 Normalized Datasheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 5.4 Criteria Selection Worksheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 5.5 Summary of Decision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 5.6 NovAtel OEM719L GNSS Receiver (NovAtel) . . . . . . . . . . . . . . . . . . . . 46 5.7 GNSS200 Receiver (Hyperion Technologies) . . . . . . . . . . . . . . . . . . . . 47 5.8 Venus 838FLPx-SPC Simulation Results . . . . . . . . . . . . . . . . . . . . . . 47 5.9 WarpSpace GPS Receiver (WarpSpace) . . . . . . . . . . . . . . . . . . . . . . 48 5.10Data Collection in an Optimal Performance Scenario . . . . . . . . . . . . . . . . . 49 5.11Summary of Decision at Receiver’s Full Performance . . . . . . . . . . . . . . . . . 49 5.12Data Collection Including Price for a 10-unit Order . . . . . . . . . . . . . . . . . . 50 5.13Assigned Weight and Influence to the Final Decision . . . . . . . . . . . . . . . . . 50 5.14Summary of Decision Including Price for a 10-unit Order . . . . . . . . . . . . . . . 51
1.2. Femtosat / CubeSat The concept of CubeSat (see Figure 1.1) was presented in (3). The idea of a smaller size satellite was initially established in 1999 in the United States. The main idea was to propose an alternative to large expensive satellites which had dominated the 20th century. Small and affordable satellites could carry out new mission concepts as well as make space accessible to a wider community, including educational institutions, such as universities and research centres, or developing countries. The concept uickly spread around the globe due to their advantages of design and construction in shorter timescales and with lower budgets. The first models were presented in 2001 by students from Aalborg University in Denmark. The first CubeSats were mainly communication satellites, but at present, the concept of making science in space with these models is firmly established and more that a thousand satellites have been launched. Furthermore, the recent trending market and the worldwide space launch sector shows an important increase in the number of small satellites missions. Indeed, in a few years, technological advancements have enabled CubeSats to achieve missions which in the past were only achievable by large satellites designed and launched by a few space agencies. During the past two decades, by definition, CubeSats clusters have been launched as piggyback payload, that is, using the excess launch capacity of a conventional rocket to put in orbit a large number of small satellites typically defined as a cluster of CubeSats. However, a new microlauncher concept (4) has bloomed in the recent years. A huge number of NewSpace launch companies from both public and private funds are developing small size launchers capable of putting up to 500 kilograms payload into orbit. This has provoked a new opportunity in the space market and these small companies are nowadays working to earn its place and make space science accessible to larger community, including the private sector. Traditional space giants such as governments or space agencies have also considered the relevance of CubeSats. As early as 2010, National Aeronautics and Space Administration –from now and on, NASA– announced the CubeSat initiative in order to launch, free of cost, small satellites designed by educational and non-profit institutions. The European Space Agency –from now and on, ESA– created the Fly Your Satellite program with the same spirit as NASA, and thus also providing students assistance in the design and construction of small satellites. Figure 1.1: 1U CubeSat Platform (Image: ISIS Space) 2
By definition, the standard one-unit (1U) CubeSat is based on a 10×10×11.35 cm3structure, although frequently several of these units combine together to build a larger satellite, e.g. such a 3U CubeSat. One satellite unit weights at most 1.33 kilograms and it must fulfil a specifications list before it gets qualified to be launched. CubeSats from 1U to 3U are manufactured with the same 10×10 cm2base and are usually launched with a common deployment system. This configuration makes these satellites able to fit in a wide range of currently used launchers as piggyback payload. On the basis of this new paradigm involving CubeSats, a continuous miniaturization trend opened the space to femtosatellites. A femtosatellite is, as its name suggests, a satellite whose main characteristic is based on its mass, which cannot exceed a total of 100 grams. The idea of femtosatellite emerged a decade ago and it was received with scepticism by the scientific community, as the severe mass constraint made the system, despite feasible, unlikely practical to achieve a mission. This view has changed with the development of Micro Electro Mechanics Systems (MEMS) sensors –which we will detail throughout this paper–, opening a wide range of opportunities to carry out missions potentially feasible using femtosatellites. Moreover, femtosatellites have frequently proved to be the only option when traditional satellites or even CubeSats units had to be discarded. Femtosatellites have opened a new field of research for the scientific community, offering valuable applications as distributed systems comprising a large number of nodes, or as a test bench for developing technologies, helping them to efficiently climb the Technology Readiness Level (TRL) ladder. Their main asset –simplicity and low cost– minimises the impact of testing advanced technologies. In addition, the possibility of launching a whole cluster favours the collection of experimental data such as statistics and behaviour. 1.3. GNSS Role Concerning the components that conform a satellite –regardless its size or type– a GNSS receiver is a device in charge of accomplishing positioning tasks, as well as tagging acceleration measurements. Specifically, in order to select the adequate receiver for a femtosatellite, its mass and size must of course be considered as critical characteristics. There are also other factors to be considered: a low cascade noise figure, a controlled multipath propagation (less likely to occur in a femtosatellite configuration), its electrical features and a temperature operational range capable to operate in orbit, among others. During this work, we will study all these aspects, and will also focus on all the regulations concerning space operations. The GNSS receiver must be COCOM free (Coordinate Committee for Multilateral Export Controls), as it should be able to transmit at an altitude higher than 60,000 feet –18,000 meters– and when the device is moving faster that 1,000 knots –1,900 km/h–. We will be carrying out a complete study about COCOM limitations in Chapter 3. 3
1.4. MEMS Technology Following the miniaturization paradigm established by consumer electronics, the main disadvantage of mechanical devices when compared to electronic ones is their being hopelessly bulky, especially when compared to the vast majority of electronic components found in integrated circuits inside satellites, mobile phones, computers, etc. This is the reason why in some situations electrical components are chosen, even when a mechanical implementation would have resulted in a simpler or higher–performance design. Here is where MEMS (micro-electromecanical system) technology makes its way (5) and appears as a straightforward solution to this usual constraint, by modifying mechanical devices, not only reducing its size but making them compatible with integrated-circuit manufacturing processes. When turning the MEMS concept into a physical device, the main mechanical structures are built by modifying –usually– silicon through state-of-art manufacturing techniques. The resulting silicon structures are later combined with integrated circuits to finally end up with a single enclosed device. The key of MEMS performance is making use of micromachined structures, sensors and actuators. A MEMS device can convert into usable data –by means of electronic circuitry– any thermal, mechanical, magnetic, electromagnetic or chemical change detected by its sensors, as well as to create physical changes rather than simply measuring them. MEMS technology can be applied to a wide variety of electronic devices. In the context of electrical engineering, it is quite common to see it incorporated into audio devices, sensor, switches and oscillators. As we can notice, in many situations MEMS have resulted into a step forward in terms of performance and implementation. Concerning the components of a femtosatellite, along this paper we will work inside the MEMS framework in order to select an adequate GNSS receiver. One good example of how these technologies are applied to the small satellite sector is Spatial R (see Figure 1.2), a ruggedized miniature GPS aided inertial navigation system manufactured by the Australian company Advanced Navigation, which provides accurate position, velocity acceleration and orientation under demanding conditions required to get the Space Certified (6). The product itself combines temperature calibrated accelerometers, gyroscopes, magnetometers and a pressure sensor with an advanced GNSS receiver. All these components are coupled in a fusion algorithm to deliver an accurate and reliable navigation and orientation. Figure 1.2: Advanced Navigation Spatial (Image: Geo-matching) 4
1.5. Thesis Structure This work is organized as follows: In Chapter 2we will expose the uses of femtosatellites in different scenarios and we will summarize its associated current research and state-of-art, regarding functional physical models (as well as those under development), focusing on the ones being at the top of the Technology Readiness Level (TRL) scale. Moreover, in this chapter we will give an introduction to the femtosat cluster for Earth’s thermosphere density determination, which is the subject of study where the GNSS receiver will be installed. Regarding the GNSS receiver itself, in this Chapter we will analyse all the restrictions such as mass, COCOM regulations, space certification –among others– regarding the development of our femtosat. Chapter 3will describe the COCOM’s legal conditions, we will explain them in detail and we will be carrying out an extensive study in the small satellites framework for the sake of a clear understanding, prior to the analysis of a suitable GNSS receivers. With all the previously acquired background, we will proceed in Chapter 4to list all the suitable options in the market inside the requirements range for our mission, making significant emphasis in their specifications and performance. Following the preceding section, in Chapter 5we will develop a complete Figure of Merit in order to evaluate all the pros and cons and establishing a uniformed criterion for the final selection, as well as any possible emergin discussion emerged during the proceedings. We will also contact the companies responsible for the manufacture and distribution of the candidate receivers, discussing availability, price (depending on the size order) and suitability of the devices with engineers and sales representatives. To sum up, in Chapter 6we will detail and justify the final decision concerning the selection of the optimal GNSS receiver for our femtosatellite as well as outline future improvements and applications. 5
CHAPTER 2. USES OF FEMTOSATELLITES Femtosatellites open a wide range of opportunities, both to perform space science experiments, and to make this field accessible to an open commercial market. Although the word ‘satellite’ might be intrinsically linked to space operations, it should be noted that femtosatellites applications do not only apply to in-orbit work but also to on ground tasks. Indeed, they can be used, for instance as a personal devices, or attached to vehicles. This conception expands even further the range of situations in which femtosats can operate, allowing to save lives or mitigate the effects of an environmental disaster. Specific actual situations in which femtosatellites play a key role involve, for instance, fast response to emergencies associated to earthquakes (3). Femtosatellites may be ”First Responders” able to perform a first mapping of the affected area. Each femtosatellite transmits a different point of view in order to make a global map of the operation theatre. The data obtained can be immediately transferred to the base camp in real time, thus allowing the ‘Decision Makers’ to take the proper action based in augmented virtual reality. Figure 2.1: An Image of the Peruvian Femtosat PUCP-SAT-1 (Image: AMSAT UK) Moreover, when the concept of microlaunchers is introduced into the femtosatellite context, a new low-cost low-cost launch and operations market arises, favouring even further space exploration and exploitation to private investors that are now able to carry out their projects using femtosatellites at an affordable cost. In the future, it is expected that fast launch decisions, adaptability, and the possibilities to put the satellite in an exact desired orbit, rather than depending on a bigger launch trajectory, will also be more readily available to the private sector. 2.1. Current Research In this section, we provide an overview of the relevant flight history of femtosats, highlighting the two missions which had a deepest impact: West Ford Needles and the Orbital Debris Radar Calibration Spheres-2. In addition, we summarize current femtosatellite projects, describe their purpose, and justify their potential advantages over conventional satellites (1). West Ford Needles cluster (see Figure 2.2) is considered the first group of femtosatellites 7
ever launched. It consisted of a project developed by the Massachusetts Institute of Technology (MIT) in 1963, even before the concept of femtosatellite was introduced, in order to simulate an artificial ionosphere with the objective of enhancing the military X-band frequency communications of the US Army during the Cold War. Even if the mission was an absolute success –being capable of enabling radio transmissions between the military–. this concept was quickly side-lined, as modern communication satellites where blooming by that time, and because of the risk associated to space debris, which was a matter of concern among the scientific community. Following West Ford’s path, another North-American experiment made its way into the femtosatellite world. The Orbital Debris Radar Calibrations Spheres (see Figure 2.3) pioneered the study and measurement of space debris in-orbit, focusing on Low Earth Orbit (LEO) and providing calibration targets for the ground-based radar in Haystack, Massachusetts. It was developed by NASA and its main objective was to calibrate the Haystack Long Range Imaging Radar (LRIR). In addition, it also allowed calibration of optical systems used for orbital debris measurements by using small, metallic spheres to bounce back the radar signal from Haystack. The mission was declared a complete success, being able to keep the radar completely still and observing the debris that passed through its viewing field. It should be noted that during the mission three spheres were deployed (each with a mass lower than 5 kilograms), together with three dipoles (each with a mass lower than 1.5 grams). The latter system could be considered as a set of three separate femtosatellites. Due to their small mass to area ratios, the three dipoles re-entered the atmosphere after 17 days in orbit, whereas the spheres lasted over a year. Figure 2.2: A sample of West Ford Program needles (Image: Arcane Radio Trivia) 8
Figure 2.3: An actual picture of the Payload bay Orbital Debris Radar Calibration System (ODERACS) taken from the Space Shuttle (Image: US National Archives) Nowadays, femtosatellites are designed in two form factors: flat and three-dimensional satellites. Whereas flat satellites are usually easier to build, due to the current good understanding of PCB technology, they present many disadvantages associated to thermal control issues provoked by a considerable surface to mass ratio (2). These temperature constraints usually end up with a lack of integrity and continuity when it comes to ensure the femtosatellite correct operation. This case gets worse in full solar illumination episodes, when the satellite clearly exceeds its maximum operational temperature. One good example of the state-of-art in femtosatellites field is the RyeFemSat (see Figure 2.4), developed by researchers at Ryerson University in Canada. It consists of a femtosatellite bus prototype with a PCBSat form factor. In their design and posterior construction, it is employed commercial-off-the-shelf (COTS) components, which results in both a significant cost reduction and development time. Its mass stands around 75 grams, with an astonishing payload capacity of 25 grams, an extraordinary milestone in the matter. This femtosatellite is equipped with a three-axis attitude determination and control based in magnetic actuators (torquers). These torquers have been produced in the rim of the PCB board, being able to deliver a moment as low as 5 nanoNewtons per meter (nN×m). The command and data handling are carried out by the Texas Instruments component CC2510, which has a radio embedded in it and works by means of a flat patch antenna, which provides a gain of 5 dBm with a data rate of 2,400 bits per second. These specifications make RyeFemSat able to provide a wide margin for high quality communications using S band at 2,450 hertz. A solar-cell structure is in charge of providing the required operating power to the femtosatellite, producing an average of 0.347 Watts, although it can reach a power peak of 1.5 Watts, which is fairly enough for the standard operations which these kind of small satellites perform. In order to supply the required power during periods in which the power source is not sufficient –e.g. during solar eclipses, or when the operational demands simply exceeds the power supply– the RyeFemSat is equipped with lithium polymer batteries, capable of providing the satellite with 2.1 Watts when required. The main satellite structure is composed of PCB fiberglass, with qualities that warrant its physical resistance and vibrations mitigation. The PCB size allows to fully fit the structure inside a CubeSat. and thus allows multiple launches if needed, as the CubeSat itself is the one in charge of dealing with vibrations and resistance. 9
Figure 2.4: RyeFemSat Scheme (Image: Ryerson University) Another relevant example concerning the state-of-art in femtosatellite technologies is the PCBSat (see Figure 2.5) developed at the University of Surrey in the United Kingdom. One of this project’s main goals is to design and build actually affordable satellites, with cost per unit lower than 300 US dollars. The function of this femtosat is thus to determine and test which satellite capabilities can be incorporated while keeping a total weight under 100 grams, and by using only commercial-off-the-shelf (COTS) components. This experiment is then a technological demonstration of cheap, mass-producible femtosatellites. Power in PCBSat is supplied again by a set of solar cells, delivering the satellite 1.3 Watts. As a backup, the satellites count on a lithium ion battery with a total capacity of 645 milliamperes hour (mAh), especially useful in solar eclipses, or when the operational demands simply exceed the power supply. Its primary structure is composed by a four-layer PCB following the standard PC-104 form factor, making it compatible with picosatellite 1simulators as the EyasSAT. The device integrates a RISC microprocessor in charge of command and data handling operations while working under minimum frequencies. Atmel 128L was the one finally selected for this purpose, due to high data rate requirements caused by a CMOS camera in the satellite payload. Other components integrating the PCBSat structure are: MaxStream Xbee Pro, used for communications in the S band at 2.4 GHz, with an emitting power of 60 milliwatts (mW) –only to be used in tests due to its low power–, a GNSS receiver denominated iTrax 30-S, in charge of attitude determination and control operations, and a passive thermal control system with temperature sensors only assembled in the battery and the solar cells. 1Small satellite of low mass and dimensions, usually under 500 kilograms. 10
Figure 2.5: PCBSat Front View (Image: ResearchGate) 2.2. A Brief Introduction to our Femtosatellite Our femtosatellite, called AtmoSwarm, is aimed to measure the thermosteric density in terms of a given height for part of this atmospheric layer. It is intended to operate in a range of heights between 100 and 250 kilometres above sea level, in clusters of tens or hundreds of units, in order to obtain data from several measurements which will later be compiled and processed. By definition of femtosatellite, the device will not have a mass greater than 100 grams. Its outer shape will be spherical, in order to minimize the complexity of eventual drag and attitude calculations. The 3D models in Figure 2.6 and in Figure 2.7 show the inner structure of our femtosatellite and its main components. Note that the second image presents the model with stabilization ballasts, aimed to minimize track maintenance. Figure 2.6: 3D Model of our Femtosat’s Interior Components (Image: Carlos Lled´ o) 11
- A laymen’s description of items to be considered; - A comparison of U.S., CoCom, neutral and eastern countries manufacturing capability and availability for each item; - The potential civilian and military uses of the item and their significance, e.g., their strategic role; - The technical feasibility of controlling the item, including the possibility and ease of substitution; - Changes in use parameters resulting from technological progress and the rate of these changes; - The present controls on design and manufacture of the equipment; - The feasibility of reverse engineering, i.e., of extracting the technology from the product and the principal military and civilian uses of the result; - Identification of critical technologies and keystone equipment. Every week representatives from member nations met in Paris in order to consider exceptions requests, majorly from companies, so a specific item could be removed from the embargoed list and consequently be freely sold. The request was reviewed by each member state and was subject to approval or denial. In the case of the United States, if the exception request came from an American exporter, it was forwarded to the State Department, which relied to the Economic Defence Advisory Committee (EDAC) the administration and consultation –along with representatives of the own State Department, as well as Defence, Commerce, Energy and Treasury Departments– in order to review and approve or deny the request. The decision was mainly based on the technical specifications of the proposed export, the proposed end-use and end user, and the availability outside CoCom, among others. Following the trend detailed in the previous section, we can notice in the following table how the number of CoCom approved exceptions raised substantially over the course of the cold war. 18
Year Value of Exceptions 1967 11 1968 8 1969 19 1970 62 1971 56 1972 124 1973 106 1974 119 1975 185 1976 162 1977 214 Table 3.3: CoCom Approved Exceptions During its First Years (1967-1977)[millions of dollars]. Source: Special Report on Multilateral Export Controls, submitted by the United States President pursuant to sec. 117 of the Export Administration Amendments of 1977 The character of the exception procedure changed over the years: it became the usual path through which export regulations could be waived at the request of the exporters in order to be able to trade with other non-member countries. We can even notice in the previous table how the United States, at the same time of being the most concerned –and worried– nation with maintaining the strictest regulations, was also responsible for half of the exception requests. This might be due to the leading role the U.S. had in computer science and technology, which were the most frequent entries on the CoCom lists, NorthAmerican firms playing the role of being one of the main suppliers of these items. It should be noted that the majority of the exception requests submitted to the Coordinating Committee were usually approved; in fact, in the last decades of operations around only 1% of requests were denied. One major issue when dealing with exceptions were the delays originated since the request was submitted until it got the final approval –it should last around two weeks but it usually went up to forty days, or even longer in case requests were submitted by other nations other than the US– being the United States the major responsible for these situations. In major cases the US played a central role in CoCom regulations, as both exports abroad from North-American territory and items originated in other –including member– countries, reexported through a US license, they had to apply to the Office of Export Administration (OEA), which was the main constraint causing delays in regulation approvals. Indeed, a CoCom delegation concluded, back in the days, that the elaborate US review process was not designed to provide a response within the required time frame; in fact, some US export control officials were not even aware of these deadlines3. In fact, there was some kind of antipathy from abroad countries, claiming that the United States foreign requests were being delayed as a measure to provide commercial advantage to US firms by holding up competitors. 3Controller General Export Controls, Mar. 1, 1979, p.11 19
3.3. The Wassenaar Arrangement Even though the Coordinating Committee for Multilateral Export Controls ceased operations on 1994 and the cold war era was over, a new threat appeared in the global map with the so-called state-sponsored terrorism. A new conflict emerged and the need to prevent rogue states – the undersecretary of state for arms and international security affairs, Lynn E. David, targeted Iran, Iraq, North Korea and Libya– from acquiring advanced technology prepared the field for the blooming of a new agreement on export restriction controls. The Wassenaar Arrangement (8) on Export Controls for Conventional Arms and Dual-Use Goods and Technologies was established in December 1995 and was named after the town in the Netherlands where negotiations were held. The agreement has the following members: Argentina, Australia, Austria, Belgium, Bulgaria, Canada, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Japan, Luxembourg, the Netherlands, New Zealand, Norway, Poland, Portugal, South Korea, Romania, Russian, Slovakia, Spain, Sweden, Switzerland, Turkey, Ukraine, the United Kingdom, and the United States. Its headquarters are located in Vienna and its official purpose is to contribute to regional and international security and stability, by promoting transparency and responsibility in transfers of conventional arms and dual-use goods and technologies, thus preventing destabilizing accumulations. ”Participating States seek, through their national policies, to ensure that transfers of these items do not contribute to the development or enhancement of military capabilities which undermine these goals, and are not diverted to support such capabilities(8). This agreement calls for the maintenance of two of the previously exposed CoCom lists: the munition list and the industrial/commercial list. It was concluded that the atomic energy list made no sense nowadays due to the coverage of the Nuclear Non-Proliferation Treaty. Again, these lists are not binding to the member states and compliance is not mandatory. 3.4. Current Situation with CoCom Regulations and GNSS Receivers Regarding GPS technology, the terminology “CoCom Regulations” refers to a standard limitation existing on GNSS tracking devices that disables tracking when the receiver estimates that it is moving faster than 1,000 knots (1,900 km/h; 1,200 mph) or at an altitude higher than 18,000 meters (59,000 ft). This regulation was intended mainly to industrial commerce in order to prevent the use of GNSS technology in intercontinental ballistic missiles or any other military applications. In Figure 3.1 we can appreciate a graphic explanation on why a satellite orbiting at an altitude greater than 18,000 meters is able to track a cruise missile: 20
Figure 3.1: A Scheme of GNSS receiver-missile communications (COOKING IDEAS) It should be noted that some manufacturers apply these limitations only when both speed and altitude limits are reached, while other manufacturers disable tracking when either limit is reached, which also affects to scientific balloons or, in our case, to our femtosatellite cluster (which is beyond both limitations). Nowadays, the CoCom limits standing for GNSS receivers are stated as: •The U.S. Department of Commerce requires that all exportable GPS products contain performance limitations so that they cannot be used in a manner that could threaten the security of the United States. The following limitations are implemented on the [named] receiver. •Immediate access to satellite measurements and navigation results is disabled when the receiver’s velocity is computed to be greater than 1000 knots, or its altitude is computed to be above 18,000 meters. The receiver continuously resets until the COCOM situation is cleared.4 It should be noted that in the same GPS receiver user guide we can find the following annex, which specifies –for those states which accept the Missile Technology Control Regime’s supervision– in its Technical Annex an exception to this rule: 11.A.3. Receiving equipment for ’navigation satellite systems’, having any of the following characteristics, and specially designed components therefor: a. Designed or modified for use in systems specified in 1.A.; or b. Designed or modified for airborne applications and having any of the following: 1. Capable of providing navigation information at speeds in excess of 600 m/s; 45700/5800 GPS Receiver User Guide, pages 20 and 124 (9) 21
2. Employing decryption, designed or modified for military or governmental services, to gain access to a ’navigation satellite system’ secure signal/data; or 3. Being specially designed to employ anti-jam features (e.g. null steering antenna or electronically steerable antenna) to function in an environment of active or passive countermeasures.5(10) Applying this annex to our situation, thus disregarding military or governmental services and being design to employ anti-jam features –which is not the case– it seems that if our GNSS receiver is capable of providing navigation information at speeds greater than 600 meters per second it needs to have a special license. To sum up, if we need to modify a GNSS receiver to remove CoCom regulations –or even acquire a specific GNSS receiver without CoCom limits–, it would be legal and acceptable if we apply for a license. Doing research and running across NASA’s State of the Art of Small Spacecraft Technology (11), we can find a relevant regulation referring to CoCom limitations in GNSS receivers inside the Guidance, Navigation and Control document: GPS units are controlled under the Export Administration Regulations (EAR) and must be licensed to remove COCOM limits. Office of the Federal Register, “FOREIGN AVAILABILITY DETERMINATION PROCEDURES AND CRITERIA,” vol. Title 15 Part 768.7, 2015.6 If we check an open access legal information site (12) for the so-called Foreign Availability criteria, we notice that: 768.2 Foreign availability described. (a) Foreign availability. Foreign availability exists when the Secretary determines that an item is comparable in quality to an item subject to U.S. national security export controls, and is available-in-fact to a country, from a non-U.S. source, in sufficient quantities to render the U.S. export control of that item or the denial of a license ineffective. For a controlled country, such control or denial is “ineffective” when maintaining such control or denying a specific license would not restrict the availability of items that would make a significant contribution to the military potential of the controlled country or combination of countries detrimental to the national security of the United States (see sections 5(a) and 3(2)(A) of the EAA.) (b) Types of foreign availability. There are two types of foreign availability: List item (1) Foreign availability to a controlled country; and (2) Foreign availability to a non-controlled country.7 From our point of view, the statement says that if a specific item is available to purchase and trade outside the United States –or any other CoCom country–, the same product in 5Missile Technology Control Regime Equipment, Software, and Technology Annex – MTCR, page 57 605. Guidance, Navigation and Control, NASA State of the Art of Small Spacecraft Technology, PDF 7Cornell Legal Information Institute 22
the US is able to apply for the license to export it, in parallel of the existing regulations. It does not mention any regulations about building a femtosatellite cluster in the thermosphere GNSS capable in the US or any other country inside the CoCom agreement, when the satellite is manufactured and launched by a member state launch provider. We have arrived to the conclusion that: as the CoCom limitation is an ITU (International Telecommunications Union, the United Nations specialized agency for information and communication technologies) requirement, it has a global character and it refers both to imports and exports. Therefore, if the GNSS receiver comes without CoCom limitations, it is considered as Dual Use and, as we have just mentioned, it needs to acquire a license in order to trade and export with it. If the device comes with pre-set CoCom limitations, it is valid for export with permission of the Department of Commerce in the case of the United States and by its corresponding counterpart in other CoCom countries. If we create or modify the firmware of a GNSS receiver in order to avoid CoCom limitations but we do not export or trade with it, the item can be considered inside the legal framework. In case we want to put into the market a CoCom free receiver we must follow the International Traffic in Arms Regulations (ITAR) rules and regulations in order not to step out of the legal frame (13). It should be noted that some available options in the market with pre-set CoCom limitations, specially the cheapest units, are hard wired and its firmware cannot be modified, as we will discuss in the following chapter. Detailed description of ITAR regulations, although important, exceeds the scope of this work. Interested readers can consult 22 U.S.C. 2778 of the Arms Export Control Act (AECA) and Executive Order 13637(14). Nevertheless, ITAR is a direct inheritor of COCOM and the most relevant aspects of its regulations follow analogous criteria. 23
CHAPTER 4. AVAILABLE OPTIONS 4.1. GNSS Devices Selection Considerations In this chapter we have carried out a study of the existing GNSS receivers in the market to subsequently elaborate a figure of merit, in order to select the optimal option according to our femtosatellite restrictions and needs. The practical value of a figure of merit can be found in the ability to compare systems with multiple properties. In this kind of systems, it is unlikely that one device outperforms all the rest in every relevant property. So, a figure of merit can provide an insight in which device is more suitable considering its overall performances. Obviously, the definition of such figures of merit is often debatable, as the weights (importance) assigned to every analyzed property has some built-in subjectivity. Nevertheless, if the figure of merit is properly defined, it will sort out a few devices as “better” than the rest, thus reducing the required work to select a single one for actual implementation. Geolocation was implemented into our daily life at an end-user level around fifteen years ago –even though these technologies were used since the sixties–, via the emergence of new devices and multiple added functions to the already existing ones. We can find GNSS technology in places such as our car, our telephone or even in the watch we wear during our daily routine, a fact which has created a huge business opportunity for component manufacturers and companies, thus providing a constant technology improvement in terms of precision, accuracy and integrity of the receivers. This development is leading the stateof-art in a wide range of sectors, from medical surgery to global communications, enabling a trustworthy tool to be based on, in order to come out with remarkable social advances. Nowadays we can find several of different options concerning GNSS receivers for terrestrial use and, according to the actual demand, they are manufactured following the guidelines of being as light, small and accurate as possible. In the space industry, which needs to be separately detailed, as it has its own particular needs, these performance indicators are virtually not fit to in-orbit operations, and we must give priority to other specifications which would be irrelevant, e.g., in car industry, such as, the resistance to radiation effects rather than the accuracy of the device. Because of the relevance of GNSS in space industry for this work, we will develop this aspect further along the following sections. Having said that, the market competition in GNSS receivers at a common use level is nowadays at its peak. In Appendix Awe detail some options with different price tag (from the lowest to the most expensive cost per unit), provided by the major manufacturers. 4.2. Space-Qualified GNSS Receivers This GNSS technology demand has naturally extended to the –now commonly known as– NewSpace1market, with the exponential increase in the past years of private companies 1NewSpace: movement encompassing a globally emerging private spaceflight industry. The term is used to refer to a global sector of new aerospace companies and ventures working independently of governments and traditional major contractors, driven by commercial motivations to broader –more socioeconomically-oriented– ends. 25
willing to operate in-orbit by means of satellite operations, space transportation or Earth observation. The continuous growth of this sector has led manufacturers and operators to begin the use of modular components, far from the traditional specifically-designed devices in use, which has resulted in the mass production of space-qualified GNSS receivers as independent products ready for the end-user adoption. In order to make a selection among the several GNSS receivers capable of operating in space environment we need to take into account their basic characteristics, apart from the performance indicators specific for our femtosatellite, that define an in-orbit operational geolocation receiver. As we have just stated, most commonly used receivers for terrestrial applications use Commercial Off The Shelf (COTS) components, which fulfil the needs and characteristics for a ground-based use. In the space arena, differences not only affect the base line design of the components, but also go further and also differs in the embedded software, as GNSS receivers for non-terrestrial use typically need to accommodate large variations of the received signal frequencies due to Doppler shifts, which is not a matter of importance in ground operations. On the other hand –as detailed in Chapter 2–, we also find regulatory issues such as the COCOM limitations set by the International Traffic on Arms Regulations (ITAR), which do not allow the proper functioning and data transmission of receivers which exceed an upper threshold of 18,000 meters (59,000 ft), or moving at velocity higher than 1,000 knots (1,900 km/h; 1,200 mph). As we concluded on the previous chapter, GNSS receivers do actually come with export control restrictions strictly related to the end-user requirements and therefore, we need to make sure the selected options are specifically designed for space operations and are classified as Dual Use receivers. The main functions of the GNSS receiver inside our femtosatellite are related to the determination of its position in Cartesian coordinates; however, the advantages of these devices in the space environment not only apply to geolocation, but are also very useful for a wide range of in-orbit processes such as on board time synchronization and geocoding of payload information, autonomous orbit control and manoeuvre planning, spacecraft formation flying, as well as on board attitude determination2. In order to perform a preliminary selection, we have taken into account several potential key specifications (15) and performance criteria to evaluate in each product; the list of relevant performances is as follows: - Mass [g]: ideally under 20 g - Power Consumption [mW]: it should not exceed 200 mW - Dual Usage (COCM free); - Volume [m3]; - Dimnsions [mm]; - Number of Channels; - Number of Antennae; - Update Rate [Hz]; - Position accuracy [m]; - Velocity accuracy [m/s]; 2An Overview of GPS Receivers for Small Satellites may be found in https://satsearch.co/ 26
- Time-To-First-Fix (TTFF) [s]; - Tolerance to Radiation [krad]; - Cost [e]; In addition, and in order to have a final filter in case two or more options are virtually equivalent to our needs, we will also consider the supplier’s reputation and location, with emphasis on export controls, as mentioned above. The GNSS receiver preliminary selection list, obtained prior to the implementation of a figure of merit, consists of the following space certified devices: GNSS-200 SERIES NAVIGATION RECEIVER – HYPERION TECHNOLOGIES The Dutch company features a low mass, low power consumption GNSS receiver designed specifically for use in CubeSats and femtosats, as its form factors fits virtually any system. The GNSS 200 series global navigation receiver (16) is part of the line called iADCS-series; consequently, it fully integrates with other attitude determination and control systems components of the same company or having similar characteristics. It is one of the options that attracts us the most for our femtosatellite mainly due to its extremely low mas (according to our 20 grams ideal limitation), the complete compliance with ITAR regulations and an acceptable power consumption compared with similar options, and it is below our limit of 200 mW. - Mass: 3 g. - Power Consumption: 150 mW. - COCOM free: Yes - Dimensions: 20 mm ×15 mm ×3 mm. - Volume: 900 mm3. - Noof Channels: multichannel 12. - Noof Antennae: 2. - Update Rate: 20 Hz. - Position Accuracy: 8 m. - Time-To-First-Fix (TTFF): 90 s. - Tolerance to Radiation: 36 krad. - Velocity Accuracy: 0.1 m/s. Figure 4.1: GNSS 200 Series Navigation Receiver (HYPERION TECHNOLOGIES) 27
CHAPTER 5. FIGURE OF MERIT In the present chapter, we use the preliminary selection of GNSS devices described in Chapter 4, in order to derive a figure of merit and, ultimately, to determine the optimal (or a few outstanding) available option(s) which will meet our requirements. The method we will be using is based on a matrix decision aimed to obtain a figure of merit. As we will see in the following sections, this method allows to specify all the device properties we are interested in, and to assign them normalised values. This helps comparison between devices and grants better informed choices. 5.1. An Overview of the Decision Matrix A figure of merit is used in engineering to characterize the performance of a device (in our case the GNSS receiver of our femtosat), relative to its alternatives, especially in the cases when different devices stand out in some of their properties, but not in others. The figure of merit is defined for specific options and characteristics in order to determine quantify their utility for an application. In the industrial area, figures of merit are commonly used as a tool to convince customers and companies to choose a particular brand among others. We will carry out this whole process following the Decision Matrix Analysis concepts (24), which essentially “mathematize” the procedures of selecting a specific option among others in order to make a rational decision. This engineering method is notably powerful in situations in which there is a number of good alternatives to choose from and many different factors to take into account, specially where there is not an obvious clear choice. Prior to the decision process which will be described in detail for our specific case, it is important to recall the main steps which should be followed in order to derive a figure of merit. - Selection of Options: (previously done in Chapter 4) to carry out an extensive study of all the available options in the market of the desired product. - Selection of Criteria: gathering of all the information and characteristics of the device (in his case our GNSS receiver), which must be taken into account. - Weight of Criteria: designating a mathematical parameter to each selected specification, in order to determine the percentage of influence in our final decision. - Rating the Options: positioning each selected option against versus the established criteria, in order to obtain a table classifying each option by its suitability. - Final Decision: Considering the most suitable options and adopt one (or more, if needed) as the finally selected for the project. In order to approximate this guideline to the most realistic scenario, we will also take into account the availability of each desired characteristic in the datasheets as well as the ordering options with the companies offering its GNSS receivers. 35
5.2. Step 1: Selection of Criteria 5.2.1. Useful Parameters to Determine the Figure of Merit We have taken into account the GNSS devices from Chapter 4, and compiled a series of main characteristics which may be relevant for their performance once implemented in our femtosatellite. It is important at this point not to allow redundancy, that is, not to consider properties which may be equivalent. This would duplicate their importance (weight) and falsely amplify their relevance in our final decision. i) Essential Parameters –Mass: ideally under 20 grams, as the whole femtosatellite should not be heavier than 100 grams. –Power Consumption: intrinsically related to the satellite battery capacity, it should not exceed 200 mW. –Volume (Dimensions): the total spherical volume of the femtosat model is intended to be notably small for sake of the project’s viability, therefore the smaller the dimensions the better the rating. –COCOM Regulations: the receiver should be ideally COCOM free, otherwise we will consider firmware modifications and costs associated with its regulation removal. If it is not COCOM free, it should be modifiable to remove the COCOM limitations. ii) Relevant Parameters –Number of Channels: the higher the number of channels, the higher the the suitability of the device. –Number of Antennae: required 4πrad coverage, otherwise field of view/4π. Essentially the use of one antenna will be enough for our femtosatellite operations. –Update Rate: desired once per second, in order to be provided with accurate enough data. Any value below that rate will be penalized. –Position Accuracy: not critical for the thermosphere density determination; an accuracy of 10 meters or less will be evaluated, virtually, in the same way. –Time-To-First-Fix (TTFF): maximum value of 60 minutes, taking into account the short operational life of our femtosatellites. –Tolerance to Radiation: receivers designed to be used in space are usually good at performing in high radiation environments; we will apply a linear relation from the most radiation hardened to the weakest option. iii) Non-Trascendental Parameters –Bits per Navigation: it is intrinsically related to the link equation, therefore the lower the number of bits per navigation, the better the rating. –Velocity Accuracy: irrelevant for our operations. 36
All these parameters will be correspondingly justified, and adjusted to the actual conditions, by assigning them a weight, in the criteria section of this chapter. Once the final decision summary is presented, we will introduce the cost variable, according to preliminary negotiations with the companies and the size of our order. 5.2.2. Data Availability It should be noted that not all the desired data is available on the datasheets provided by the manufacturers and we need to adapt our parameters to the actual situation (see Figure 5.1). Fortunately, most of the information we required from the receivers –specially the essential– is fully available for every device and we just needed to make slight modifications and adjustment to our tables: Figure 5.1: Data availability information for the considered GNSS receivers. Available and nonavailable information are shown in green and red respectively. Note that most of the data regarding Bits per Navigation and Frequencies are not shown on the datasheets, and therefore we will not be evaluating them. Fortunately, both of them are virtually irrelevant regarding our final decision regarding the GNSS receiver inside the femtosatellite. Therefore this lack of information will not affect the suitability of our decision matrix. On other hand, several specifications are not available for certain models, such as update rate,tolerance to radiation or velocity accuracy (again, none of them are essential parameters). In this case, we approximate these values to the usual minimum in space-certified GNSS receivers, adopting a conservative position even if the actual specification features a better performance. In other situations in which the datasheet provides a range of values –for instance, update rates between 1 Hz and 20 Hz or a position lower than 5 meters–, we again adopt the worst-case scenario, taking the most conservative value for our mathematical model. Additionally, in Chapter 6we discuss the variability of results when adopting optimistic values in a full-performance scenario. 37
5.3. Step 2: Data Collection and Approximations The tables corresponding to Figure 5.2 show all the information collected from the receiver datasheets and their respective approximations, which will be used to build the decision summary: All the datasheets provided by the providers can be consulted in the Appendix Bof this work. Figure 5.2: Datasheet Information and Approximations. 5.4. Step 3: Data Ratings Once all the necessary data are presented, we need to apply normalized ratings to our selected criteria. In order to assign the optimal value to each characteristic of the receivers, we create a specific grading scale for every parameter listed in the previous step. To do this, we take the data collected and compare them to a pre-stablished set of conditions with defined thresholds. We assign a weight to every property by giving a value of 1 to the best option and 0.1 to the worst, and assume a linear relation to determine the weights for intermediate values. In the next paragraphs we find the slope and independent term to such fits for all the properties taken into account to determine our figure of merit. 38
Mass We need to take into account that our desired mass is supposed to be below 20 grams but we have decided to include options up to 160 grams –which could prove useful for the University of Samara femtosatellite–. Therefore, in this case we will apply a standard linear regression in order get a figure for each mass value: Setting the upper and lower edges: Mass [g] Normalized Value 0.3 1 160 0.1 Developing the function to obtain each mass figure ( fM): y=ax +b 1=0.3a+b 0.1=160 a+b a=−5.64 ×10−3 ,b=1.0017 Therefore: fM=−5.64 ×10−3M+1.0017 Power Consumption Our maximum power consumption should be located below 200 mW, as it is directly related with the size and duration of the battery. We have adjusted our parameters to the actual power consumption of the selected options. Setting the upper and lower edges: Power Consumption [mW] Normalized Value 130 1 1600 0.1 Proceeding as in the mass case, we obtain for the figure fPC: fPC =−6.1225 ×10−4PC +1.0796 Volume Our satellite is characterized, among other things, by its small size. Consequently, the miniaturisation of all the components is an essential aspect in order to keep the femtosatellite’s configuration. As we do not have any significant boundary for this aspect –apart from common sense–, we will apply a linear regression. 39
Setting the upper and lower edges: Volume [mm3] Normalized Value 130 1 96048 0.1 Proceeding as in the mass case, we obtain for the figure ( fV): fV=−9.383 ×10−6V+1.00123 COCOM Regulations All our options are –or can be– delivered as COCOM free and therefore in this case we do not need to assign a rating based on a gradient scale. Number of Channels The number of channels that a satellite can operate with is strictly related to its availability but also –in a minor way– to its power consumption. Therefore, we will not be applying a remarkable penalization within options among 24 channels or more. Setting the upper and lower edges: Noof Channels Normalized Value 167 1 1 0.5 Proceeding as in the mass case, we obtain for the figure fNC: fNC =3.012 ×10−3×NC +0.49699 Number of Antennae In this case the number of antennae in the selected options differs between one and two. As the femtosatellite could operate with only one antenna, again we will not be making an excessive difference between the two configurations and we will start our rank at 0.5. Setting the upper and lower edges: Noof Antennae Normalized Value 2 1 1 0.5 Proceeding as in the mass case, we obtain for the figure fNA: fNA =−0.5NA +1.5 40
Update Rate We need a minimum of 1 Hz in order to receive enough accurate data in our density measurements. More than that would have no significant difference in our determinations and consequently the difference within 1 Hz and more will be drastically reduced, only up to a 30% margin. Setting the upper and lower edges: Update Rate [Hz] Normalized Value 25 1 1 0.7 Proceeding as in the mass case, we obtain for the figure fUR: fUR =0.0125UR +0.6875 Position Accuracy For the nature of our operations, we will not be needing a position accuracy under 10 meters, as the function of our femtosatellite is not related with terrestrial navigation or similar. As in the previous case, we will not strictly penalize options with an accuracy on or under our desired minimum. Setting the upper and lower edges: Position Accuracy [m] Normalized Value 1.8 1 10 0.7 Proceeding as in the mass case, we obtain for the figure fPA: fPA =−0.0367PA +1.0659 Time-To-FirstFix (TTFF) The Time-To-FirstFix defines the period in which the receiver starts to send information to the ground station since the beginning of the satellite’s operational life. Among our specifications, we state that we should require a TTFF below 60 minutes, a fulfilled feature by all the available options in the market. Therefore, we will be adapting our gradient to the actual offer but, taking into account our wide requirements, we will not be hardly penalizing any options with a long Time-To-First-Fix. Setting the upper and lower edges: Time-To-FirstFix (TTFF) [s] Normalized Value 15 1 450 0.7 41
Proceeding as in the mass case, we obtain for the figure fTTFF: fTTFF =−6.8967 ×10−4TTFF +1.0103 Tolerance to Radiation Nowadays, especially with the recent regulations, all the GNSS receivers for space use are radiation hardened. From this point, we will be applying a linear regression within the most resistant and the weakest one without penalizing any of them in excess, up to a 50% difference rate. Setting the upper and lower edges: Tolerance to Radiation [krad] Normalized Value 36 1 5 0.5 Proceeding as in the mass case, we obtain for the figure fTR: fTR =0.0161TR +0.4194 Velocity Accuracy As this parameter remains irrelevant to our operations, we apply a linear regression from lowest to highest accuracy but we will not be penalizing inaccurate options in excess. Setting the upper and lower edges: Velocity Accuracy [m/s] Normalized Value 0.15 1 0.03 0.5 Proceeding as in the mass case, we obtain for the figure fVA: fVA =4.16VA +0.375 42
5.4.1. Collection of Normalized Data Once we have obtained all the corresponding normalized values for every criterion taken into account, we come up with the following figure (5.3), where we have crossed both the data obtained with every GNSS receiver candidate model. Figure 5.3: Normalized Datasheet This values will be employed in the next sections to determine the figure of merit of the different devices considered so far. 5.5. Step 4: Weight and Rank of Criteria Once we have quantified the properties of the GNSS receivers in an easily comparable way, we need to define the applicable weight to each parameter in a one to ten scale, according to the importance according to our specific needs as well as to the influence we want it to have into our final decision. As we have exposed in the first step, we already divided the receiver characteristics intro three major groups in relation to is relevance. From that point, we have come up to the consensus of assigning the weights to each feature listed in Figure 5.4. Figure 5.4: Criteria Selection Worksheet 43
COCOM removal costs, in order to approximate as much as possible our Figure of Merit for an actual case of –in this example– a 10-unit GNSS receiver order (see Figures 5.12, 5.13 and 5.14). Figure 5.12: Data Collection Including Price for a 10-unit Order Figure 5.13: Assigned Weight and Influence to the Final Decision 50
Figure 5.14: Summary of Decision Including Price for a 10-unit Order Including the price as a parameter reflects the weakness of options such as the WarpSpace GPS Receiver, with an elevated base price tag and the cons of being a Japanese company bounded by export regulations. Also in this section, we can notice how Venus 838FLPx fully complies with our price standards and notably stands out from the other alternatives, mainly due to the low price regarding the chip, even if the company is based in Taiwan and there is also the need to apply for an export license. 51
CHAPTER 6. CONCLUSIONS AND FUTURE WORK 6.1. Conclusions We have achieved our main goal of shortlisting GNSS receivers suitable for implementation in a femtosatellite aimed to take measurements of thermospheric densities (AtmoSwarm). In doing so, we may extract the following conclusions from our work: i) Concerning the selection of the most appropriated GNSS receiver for our femtosatellite, we have concluded, by using the Figure of Merit approach, that the Venus 838FLPx manufactured by the Taiwanese company SkyTraq is the receiver which fits better our mission requirements. This model not only features an extremely light mass or low power consumption, but its price tag is ten times lower than any other competitor’s. This is mainly due to the fact that it is sold without a PCB board and it is only available with the chip. Fortunately, from the practical point of view, this meets our needs, as we aim to integrate the receiver in an electronic board along with the rest of the electronic components (microprocessor, accelerometers, the flash memory...) for the sake of saving as much mass and volume inside the structure as possible. This way we can we save up to 19.7 grams, which represents almost 20% of the total mass of our satellite and it will result certainly useful during the development and selection of the other components. Moreover, the same chip is integrated in another shortlisted candidate model: the WarpSpace GPS receiver, which could be considered as a preliminary test option, prior to the final integration of the Venus 838FLPx inside the satellites’ board. ii) Our Figure of Merit table does not only provide us with an optimal option, but also highlights the four best candidates (those scoring above 50) which are virtually fit for our satellite. This may be very helpful to find an alternative in case we encounter unexpected events, such as quality issues, bureaucratic or shipping setbacks, etc. Besides, in this research we have come up to establish contact with the major companies specialized in GNSS receivers for small satellites and we have ranked them according to our needs, which gives us the possibility to refresh our model following the market development with new receiver models or updated versions of the existing ones. iii) Apart from checking the suitability of the decision matrix approach to our problem, we have checked its flexibility when relaxing a specific variable threshold or adding an additional variable (see section 5.8.). Furthermore, it is important to point out that this approach can be exported to any type of satellite component, simply by changing or adding new entries associated to the new required variable to consider, or in some circumstances, by merely changing the weights associated to each variable. Of course, the method is applicable both to small and standard-size satellites. 53
6.2. Lines of Future Work and Development The present work is integrated in a more comprehensive project, aimed to the design and construction of the femtosatellite AtmoSwarm. The expertise achieved here may be applied to different aspects of the development of this project. For instance: i) The decision matrix developed may be extended in the future, including the new GNSS devices, which will certainly appear in the blooming sector of space electronics. It is expected to speed significantly future decision process. ii) The method described will be exported and applied to the choice of alternative components related to the development of our femtosatellite, such as accelerometers and microprocessors. iii) There is an intention to automatize this selection method via coding, which would standardise the procedures for any type of decision and it would save time when adding more data or modifying existing one. 54
BIBLIOGRAPHY [1] Carlos Lled´ o Ardila. A swarm of femtosatellites for thermospheric density determination. 2015. [2] Marc Gabarr´ o Olsina. A system to determine the inertia tensor of small satellites. 2019. [3] Joshua Tristancho. Implementation of a femto-satellite and a mini-launcher. 2010. [4] Microlauncher applications. Technical report, 2018. [5] Robert Keim. Introduction to mems (microelectromechanical systems). December 2018. URL: https://bit.ly/2S6Sjdu. [6] Advanced Navigation. SPATIAL Inertial Navigation System. URL: https://www. advancednavigation.com/product/spatial. [7] Princenton University. Chapter viii: Multilateral export control policy: The coordinating committee (cocom). 1979. URL: https://www.princeton.edu/˜ota/disk3/ 1979/7918/791810.PDF. [8] Michael Knes. Coordinating committee for multilateral export controls and the wassenaar arrangement. URL: https://bit.ly/38abrwY. [9] Trimble Navigation Ltd. 5700/5800 GPS Receiver User Guide, 2003. URL: https: //bit.ly/2SsZyM4. [10] Missile Technology Control Regime. Missile technology control regime (mtcr). equipment, software and technology annex. 11th october 2019. Technical report, 2019. URL: https://mtcr.info/wordpress/wp-content/uploads/2019/10/ MTCR-TEM-Technical_Annex_2019-10-11-1.pdf. [11] National Aeronautics and Space Administration (NASA); Bruce Yost. 05. guidance, navigation and control. Technical report, 2019. URL: https://sst-soa.arc.nasa. gov/05-guidance-navigation-and-control. [12] Conrell Law School. Cornell legal information institute. URL: https://www.law. cornell.edu/cfr/text/15/768.2. [13] StackExchange. Current situation with cocom regulations and gps receivers. 2017. URL: https://bit.ly/2Uxh8kM. [14] U.S. Department of State Directorate of Defense Trade Controls. The international traffic in arms regulations (itar). URL: https://bit.ly/39dfV5W. [15] Narayan Prasad. An overview of gps receivers for small satellites. November 2019. URL: https://bit.ly/2UvDC5r. [16] Hyperion Technologies B.V. GNSS200 Datasheet. [17] SkyTraq Technology Inc. Venus 838FLPx GPS Receiver Datasheet. 55
[18] WarpSpace Inc. WarpSpace GPS Receiver Datasheet. [19] DLR Deutsches Zentrum f¨ ur Luft-und Raumfahrt. Phoenix GPS Receiver Datasheet. [20] Surrey Satellite Technology Ltd. Space GNSS Receiver SGR-Ligo Datasheet. [21] Surrey Satellite Technology Ltd. Space GPS Receiver SGR-05P Datasheet. [22] NovAtel Inc. OEM719 Datasheet. [23] Pumpkin Inc. GPSRM 1 GPS Receiver Module Datasheet. [24] Mind Tools Content Team. Decision matrix analysis. URL: https://www. mindtools.com/pages/article/newTED_03.htm. [25] Maestro Wireless Solutions Ltd. A2235H Datasheet. URL: https://bit.ly/ 2OBXMaq. [26] Globalsat Technology Corporation. EM-506 Datasheet. URL: http://cdn. sparkfun.com/datasheets/GPS/EM506_um.pdf. [27] LOCOSYS Technology Inc. LS20031 Datasheet. URL: https://cdn.sparkfun. com/datasheets/GPS/LS20030˜3_datasheet_v1.3.pdf.
APPENDICES
APPENDIX A. TERRESTRIAL-USE GNSS RECEIVERS A2235H - MAESTRO WIRELESS SOLUTIONS Featuring (25): - SMT-based integrated GPS antenna module: low assembly cost - 17.8 mm ×16.5 mm ×7.1 mm - 21 mA average tracking: low power consumption -−163 dBm Tracking Sensitivity: tracking in difficult environment) - RF Switch: dual antenna support - Mass: 4 g - Price per unit: 17,51 eFigure A.1: A2235H GNSS Receiver (MAESTRO WIRELESS SOLUTIONS) EM-506 – GlobalSat Featuring (26): - 48-Channel Receiver - Sensitivity: –163 dBm - Position Accuracy: 2.5 m - TTFF Hot Start: 1 s - 45-55mA at 4.5-6.5 V - 30 mm ×30 mm ×10.7 mm - Mass: 16 g, including cable - Price per unit: 39,95 $ Figure A.2: EM-506 GNSS Receiver (GlobalSat) 59
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 3 TECHNICAL SPECIFICATIONS Receiver Type L1 C/A code GPS QZSS 167 channel Venus 8 engine Accuracy Position 2.5m CEP Velocity 0.1m/sec Timing 10ns Open Sky TTFF 29 second cold start 1 second hot start Reacquisition < 1s Sensitivity -165dBm tracking -148dBm cold start Update Rate 1 / 2 / 4 / 5 / 8 / 10 / 20 / 25 / 40 / 50 Hz (default 1Hz) Dynamics 4G Operational Limits Velocity 10Km/s+ Datum Default WGS-84 Interface UART LVTTL level Baud Rate 4800 / 9600 / 38400 / 115200 Protocol NMEA-0183 V3.01, GGA, GLL, GSA, GSV, RMC, VTG, ZDA SkyTraq Binary Main Supply Voltage 2.8V ~ 3.6V (Venus838FLPx-L) 2.8V ~ 3.6V, 1.08V ~ 1.32V (Venus838FLPx-D) Backup Voltage 2.5V ~ 3.6V Current Consumption (3.3V) Acquisition Tracking Number of Search Engine 2 4 6* 8 Venus838FLPx-L 39mA 45mA 51mA 59mA 33mA Venus838FLPx-D** 20mA 23mA 26mA 30mA 16mA * default 6 search engine used ** 90% efficiency 3.3V-to-1.2V switch-mode regulator is used Operating Temperature -40 ~ +85 deg-C Storage Temperature -40 ~ +125 deg-C Package LGA69 10mm x 10mm x 1.3mm, 0.8mm pitch Weight 0.3g
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 4 BLOCK DIAGRAM Figure-1 GPS Receiver based on Venus838FLPx
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 5 Venus838FLPx PIN-OUT DIAGRAM Figure-2 Venus838FLPx Pin-Out Diagram Venus838FLPx PIN DEFINITION Pin Numbe r Signal Name Type Description 1 RSTN Input Active LOW reset input, 3.3V LVTTL 2 VCC33I Power Input Main voltage supply input, 2.8V ~ 3.6V 3 GPIO1 / RXD1 Bidir General purpose I/O pin, 3.3V LVTTL Or receive input of the asynchronous UART port Default not used 4 GPIO25 / M_MISO Bidir General purpose I/O pin, 3.3V LVTTL Or SPI master input Default not used 5 GPIO24 / M_SCK Bidir General purpose I/O pin, 3.3V LVTTL Or SPI master clock Default not used 6 GPIO26 / M_MOSI Bidir General purpose I/O pin, 3.3V LVTTL Or SPI master output Default not used 7 LED / GPIO0 Bidir Navigation status indicator (default) Or General purpose I/O. 3.3V LVTTL 8 GPIO2 / TXD1 Bidir General purpose I/O pin. 3.3V LVTTL Or transmit output of the asynchronous UART port Default not used
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 6 9 BOOT_SEL Bidir Boot mode selection. Pull-high or pull-low 1: execute from internal Flash 0: execute from internal ROM This is opposite of Venus638FLPx 10 GND Power System ground 11 GND Power System ground 12 GPIO7 / P1PPS2 Bidir General purpose I/O pin, 3.3V LVTTL Second P1PPS output Default unused 13 GPIO6 / M_CSN2 Bidir General purpose I/O pin, 3.3V LVTTL Or SPI master chip select #2 Default not used 14 GPIO5 / SDA Bidir General purpose I/O pin, 3.3V LVTTL Or I2C serial data Default not used 15 GND Power System ground 16 GPIO23 / M_CSN0 Bidir General purpose I/O pin, 3.3V LVTTL Or SPI master chip select #0 Default not used 17 NC Not connected, empty pin 18 VBAT Power Input Supply voltage for internal RTC and backup SRAM, 2.5V ~ 3.6V. VBAT should be powered by non-volatile supply voltage to have optimal performance. Maximum VBAT current draw when VCC33I is removed is 35uA. If VBAT is connected to VCC33I, powered off as VCC33I power is removed, then it’ll cold start every time. For applications that do not care lesser performance cold starting every time, this pin can be connected to VCC33I. Must not be left unconnected. 19 GND Power System ground 20 NC Not connected, empty pin 21 GND_RF Power RF section system ground 22 GND_RF Power RF section system ground 23 NC Not connected, empty pin 24 GND_RF Power RF section system ground 25 GND_RF Power RF section system ground 26 NC Not connected, empty pin 27 GND_RF Power RF section system ground 28 GND_RF Power RF section system ground 29 GND_RF Power RF section system ground 30 NC Not connected, empty pin 31 GND_RF Power RF section system ground 32 RFIN Input GPS signal input, connect to GPS antenna. 33 GND_RF Power RF section system ground 34 NC Not connected, empty pin 35 NC Not connected, empty pin 36 NC Not connected, empty pin 37 GPIO4 / SCL Bidir General purpose I/O pin, 3.3V LVTTL Or I2C SCL clock Default not used 38 GPIO30 / MS_MOSI Bidir General purpose I/O pin, 3.3V LVTTL Or SPI master/slave data output Default not used 39 GPIO31 / MS_MISO Bidir General purpose I/O pin, 3.3V LVTTL Or SPI master/slave data input Default not used 40 P1PPS / GPIO3 bidir 1 pulse per second output. Active after position fix; goes HIGH for about 800usec at 1Hz, 3.3V LVTTL (default) Or general purpose I/O pin 41 GPIO29 / MS_SCK Output General purpose output pin, 3.3V LVTTL Or SPI master/slave clock Default not used 42 RXD0 Input Received input of the asynchronous UART port. Used to input binary command to the GPS receiver. 3.3V LVTTL 43 GPIO28 / MS_CSN Bidir General purpose I/O pin, 3.3V LVTTL Or SPI master/slave chip select Default not used
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 7 44 TXD0 Output Transmit output of the asynchronous UART port. Used to output standard NMEA-0183 sentence or response to input binary command. 3.3V LVTTL 45 GPIO14 Bidir General purpose I/O pin, 3.3V LVTTL Default not used 46 GPIO22 / M_CSN1 Bidir General purpose I/O pin, 3.3V LVTTL Or SPI master chip select #1 Default not used 47 GPIO9 Bidir General purpose I/O pin, 3.3V LVTTL Default not used 48 GPIO16 Bidir General purpose I/O pin, 3.3V LVTTL Default not used 49 GND System ground 50 GPIO13 Bidir General purpose I/O pin, 3.3V LVTTL Default not used 51 GPIO8 Bidir General purpose I/O pin, 3.3V LVTTL Default not used 52 GPIO27 Input General purpose I/O pin, 3.3V LVTTL Default not used 53 GPIO15 Bidir General purpose I/O pin, 3.3V LVTTL Default not used 54 GPIO20 / PWM0 Bidir General purpose I/O pin, 3.3V LVTTL Or PWM output #0 Default not used 55 GPIO12 Bidir General purpose I/O pin, 3.3V LVTTL Default not used 56 NC / V12 NC pin for Venus838FLPx-L 1.2V supply input pin for Venus838FLPx-D 57 GPIO21 / PWM1 Output General purpose I/O pin, 3.3V LVTTL Or PWM output #1 Default not used 58 VCC33I Power Input Main voltage supply input, 2.8V ~ 3.6V 59 GPIO10 Bidir General purpose I/O pin, 3.3V LVTTL Default not used 60 GND Power System ground 61 GND_RF Power RF section system ground 62 GND_RF Power RF section system ground 63 GPIO11 Bidir General purpose I/O pin, 3.3V LVTTL Default not used 64 GND Power System ground 65 GND_RF Power RF section system ground 66,67,68 NC Not connected, empty pin 69 GND_RF Power RF section system ground When using Venus838FLPx-L to replace Venus634FLPx, pin-45 ~ pin-69 can all be left unconnected. When using Venus838FLPx-D, 1.2V need to be supplied at pin-56 The NC pins are to be left unconnected. DC CHARACTERISTICS OF DIGITAL INTERFACE Below is when VCC3I is at nominally 3.3V Paramete r Min. Typ. Max. Units Input Low Voltage 0.8 Volt Input High Voltage 2.0 Volt Output Low Voltage, Iol = 4 ~ 7.8mA 0.4 Volt Output High Voltage, Ioh = 4.6 ~ 15.4mA 2.4 Volt
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 8 MECHANICAL DIMENSION RECOMMENDED PCB FOOTPRINT Figure-3 Recommended PCB Footprint.
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 9 RECOMMENDED REFLOW PROFILE Temperature (℃) 25 82.5 140 150 160 170 180 190 200 225 250 250 215 185 155 125 95 65 35 Time(minute) 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 Profile Description SnPb Eutectic Process Lead Free Process Preheat Maximum Temperature 100+/-10 ℃ 140+/-10 ℃ Time(ΔT) 40~60s 50~70s Ramp-Up Ramp-Up Rate 1 ℃/s Max. 1 ℃/s Max. Time(ΔT) 120~150s 160~200s Reflow Maximum Temperature Peak Temp. Peak Temp. Minimum Temperature 180+/-5℃ 200+/-10℃ Peak Temperature 220+/-2℃ 250+/-2℃ Time(ΔT) during Peak Temp.+/-2℃ 10~30s 20~40s Reflow Time(ΔT) 120~150s 120~150s Cooling Cooling Rate 1.5 ℃/s Max 1.5 ℃/s Max Time(ΔT) 60~120s 150~180s
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 10 VENUS838FLPx-L APPLICATION CIRCUIT
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 11 VENUS838FLPx-D APPLICATION CIRCUIT
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 12 APPLICATION CIRCUIT INTERFACE SIGNALS STS: Signal to indicate GPS position status, 3.3V LVTTL. Active low for no-fix, toggle every second after position fix. P1PPS: 1 pulse per second time-mark (3.3V LVTTL) RSTN: Active low reset input VCC33: 3.3V power input RXD0: UART input (3.3V LVTTL) TXD0: UART output (3.3V LVTTL)
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 19 GSA – GNSS DOP and Active Satellites GPS receiver operating mode, satellites used in the navigation solution reported by the GGA or GNS sentence and DOP values. Structure: $GPGSA,A,x,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,x.x,x.x,x.x*hh<CR><LF> 1 2 3 3 3 3 3 3 3 3 3 3 3 3 4 5 6 7 Example: $GPGSA,A,3,05,12,21,22,30,09,18,06,14,01,31,,1.2,0.8,0.9*36<CR><LF> Field Name Example Description 1 Mode A Mode ‘M’ = Manual, forced to operate in 2D or 3D mode ‘A’ = Automatic, allowed to automatically switch 2D/3D 2 Mode 3 Fix type 1 = Fix not available 2 = 2D 3 = 3D 3 Satellite used 1~12 05,12,21,22,3 0,09,18,06,14, 01,31,, Satellite ID number, 01 to 32, of satellite used in solution, up to 12 transmitted 4 PDOP 1.2 Position dilution of precision (0.0 to 99.9) 5 HDOP 0.8 Horizontal dilution of precision (0.0 to 99.9) 6 VDOP 0.9 Vertical dilution of precision (0.0 to 99.9) 7 Checksum 36
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 20 GSV – GNSS Satellites in View Number of satellites (SV) in view, satellite ID numbers, elevation, azimuth, and SNR value. Four satellites maximum per transmission. Structure: $GPGSV,x,x,xx,xx,xx,xxx,xx,…,xx,xx,xxx,xx *hh<CR><LF> 1 2 3 4 5 6 7 4 5 6 7 8 Example: $GPGSV,3,1,12,05,54,069,45,12,44,061,44,21,07,184,46,22,78,289,47*72<CR><LF> $GPGSV,3,2,12,30,65,118,45,09,12,047,37,18,62,157,47,06,08,144,45*7C<CR><LF> $GPGSV,3,3,12,14,39,330,42,01,06,299,38,31,30,256,44,32,36,320,47*7B<CR><LF> Field Name Example Description 1 Number of message 3 Total number of GSV messages to be transmitted (1-5) 2 Sequence number 1 Sequence number of current GSV message 3 Satellites in view 12 Total number of satellites in view (00 ~ 20) 4 Satellite ID 05 Satellite ID number, GPS: 01 ~ 32, SBAS: 33 ~ 64 (33 = PRN120) 5 Elevation 54 Satellite elevation in degrees, (00 ~ 90) 6 Azimuth 069 Satellite azimuth angle in degrees, (000 ~ 359 ) 7 SNR 45 C/No in dB (00 ~ 99) Null when not tracking 8 Checksum 72
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 21 RMC – Recommended Minimum Specific GNSS Data Time, date, position, course and speed data provided by a GNSS navigation receiver. Structure: $GPRMC,hhmmss.ssssss,A,dddmm.mmmm,a,dddmm.mmmm,a,x.x,x.x,ddmmyy,,,a*hh<CR><LF> 1 2 3 4 5 6 7 8 9 10 11 Example: $GPRMC,111636.998665,A,2447.0949,N,12100.5223,E,0.000,000.0,130712,,,A*52<CR><LF> Field Name Example Description 1 UTC time 0111636.9986 65 UTC time in hhmmss.ssssss format (000000.000000 ~ 235959.999999) 2 Status A Status ‘V’ = Navigation receiver warning ‘A’ = Data Valid 3 Latitude 2447.0949 Latitude in dddmm.mmmm format Leading zeros transmitted 4 N/S indicator N Latitude hemisphere indicator ‘N’ = North ‘S’ = South 5 Longitude 12100.5223 Longitude in dddmm.mmmm format Leading zeros transmitted 6 E/W Indicator E Longitude hemisphere indicator 'E' = East 'W' = West 7 Speed over ground 0.000 Speed over ground in knots (000.000 ~ 19438.445) 8 Course over ground 000.0 Course over ground in degrees (000.0 ~ 359.9) 9 UTC Date 130712 UTC date of position fix, ddmmyy format 10 Mode indicator A Mode indicator ‘N’ = Data not valid ‘A’ = Autonomous mode ‘D’ = Differential mode ‘E’ = Estimated (dead reckoning) mode ‘M’ = Manual input mode ‘S’ = Simulator mode 11 checksum 52
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 22 VTG – Course Over Ground and Ground Speed The Actual course and speed relative to the ground. Structure: GPVTG,x.x,T,,M,x.x,N,x.x,K,a*hh<CR><LF> 1 2 3 4 5 Example: $GPVTG,000.0,T,,M,0.000,N,0.000,K,A*0D<CR><LF> Field Name Example Description 1 Course 000.0 True course over ground in degrees (000.0 ~ 359.9) 2 Speed 0.000 Speed over ground in knots (000.000 ~ 19438.445) 3 Speed 0.000 Speed over ground in kilometers per hour (0000.000 ~ 36000.000) 4 Mode A Mode indicator ‘N’ = not valid ‘A’ = Autonomous mode ‘D’ = Differential mode ‘E’ = Estimated (dead reckoning) mode ‘M’ = Manual input mode ‘S’ = Simulator mode 5 Checksum 0D
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 23 ZDA – Time & Date UTC, day, month, year and local time zone. Structure: $GPZDA,hhmmss.ssssss,xx,xx,xxxx,xx,xx*hh<CR><LF> 1 2 3 4 5 6 7 Example: $GPZDA,111636.998665,13,07,2012,00,00*6D<CR><LF> Field Name Example Description 1 UTC time 111636.99866 5 UTC time in hhmmss.sss format (000000.000000 ~ 235959.999999) 2 Day 13 Day, 01 to 31 3 Month 07 Month, 01 to 12 4 Year 2012 Year in yyyy format 5 Local zone hours 00 Local zone hours, 00 to +/- 13 hrs 6 Local zone minutes 00 Local zone minutes, 00 to +59 7 checksum 6D
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 24 ORDERING INFORMATION Part Number Description Venus838FLPx-L-SPC Flash version GPS receiver (internal 1.2V LDO version) Venus838FLPx-L with customized firmware for CubsSat application Venus838FLPx-D-SPC Flash version GPS receiver (external 1.2V version) Venus838FLPx-D with customized firmware for CubeSat application SkyTraq Technology, Inc. 4F, No.26, Minsiang Street, Hsinchu, Taiwan, 300 Phone: +886 3 5678650 Fax: +886 3 5678680 Email: [email protected] © 2017 SkyTraq Technology Inc. All rights reserved. Not to be reproduced in whole or part for any purpose without written permission of SkyTraq Technology Inc (“SkyTraq”). Information provided by SkyTraq is believed to be accurate and reliable. These materials are provided by SkyTraq as a service to its customers and may be used for informational purposes only. SkyTraq assumes no responsibility for errors or omissions in these materials, nor for its use. SkyTraq reserves the right to change specification at any time without notice. These materials are provides “as is” without warranty of any kind, either expressed or implied, relating to sale and/or use of SkyTraq products including liability or warranties relating to fitness for a particular purpose, consequential or incidental damages, merchantability, or infringement of any patent, copyright or other intellectual property right. SkyTraq further does not warrant the accuracy or completeness of the information, text, graphics or other items contained within these materials. SkyTraq shall not be liable for any special, indirect, incidental, or consequential damages, including without limitation, lost revenues or lost profits, which may result from the use of these materials. SkyTraq products are not intended for use in medical, life-support devices, or applications involving potential risk of death, personal injury, or severe property damage in case of failure of the product.
SkyTraq Technology, Inc. www.skytraq.com.tw empower mobility, without uncertainty 25 Change Log Version 4, October 8, 2019 1. Updated NMEA speed related fields Version 3, November 22, 2018 1. Increased max velocity to 10Km/sec+ Version 2, April 19, 2018 1. Lowered max velocity to 7.8Km/sec+ Version 1, October 5, 2017 1. Initial release
The Phoenix GPS receiver is a 12-channel single-frequency receiver specifically designed for high-dynamics and space applications. The receiver is based on Zarlink’s advanced GP4020 baseband processor, which results in a small size and low power consumption. In combination with DLR’s proprietary firmware, the receiver offers precision measurements for advanced navigation applications as well as robust tracking even under extreme dynamics. Three specific receiver versions (Phoenix-S/- XNS and Phoenix-HD) are offered to optimally support both orbital and ballistic missions. Recommended applications of the Phoenix GPS receiver in low-Earth orbit (LEO) include real-time navigation, onboard timesynchronization, precise-orbit determination and spacecraft formation flying. On sounding rockets or launch vehicles the receiver provides navigation and timing information for range-safety operations, flight performance monitoring and experiment execution. Dedicated qualifications tests have demonstrated that the Phoenix GPS receiver tolerates the environmental conditions (thermal-vacuum, vibration, ionizing radiation) encountered in representative space missions despite the exclusive use of commercial-off-the-shelf (COTS) electronics components. The high performance and minimal resource requirements make the Phoenix receiver an ideal candidate for innovative space missions with tight budgets and limited quality assurance requirements. Phoenix-S and -XNS receivers for nanoand micro-satellites have been selected by various universities and space agencies. Among others, they will provide precision relative navigation for an upcoming formation flying mission. The Phoenix-HD receiver constitutes the primary tracking system for future sounding rocket missions within the European microgravity program and the German national space program. Phoenix Spaceborne GPS Receiver
Phoenix GPS Data Sheet Issue 1.1, 2 Jan. 2007 Phoenix Receiver Versions Customers can select among various versions of the Phoenix receiver to cover a wide range of mission applications: The basic Phoenix-S receiver is optimized for use on LEO satellites. It offers a built-in orbit propagator to aid the initial acquisition and to allow a short time-to-first-fix. Low-noise code and carrier phase measurements are achieved through carefully optimized tracking loops. Full cycle integer ambiguities enable precision relative navigation in carrier phase differential GPS applications. The Phoenix-XNS extends the functionality of the basic receiver version by a built-in navigation filter for LEO satellites. It offers a dynamically smoothed and continuous navigation solution even in case of limited GPS satellite visibility. The measurement processing inside the Phoenix-XNS provides a rigorous elimination of ionospheric path delays and enables a realtime navigation accuracy meeting the requirements of advanced remote sensing satellites. The Phoenix-HD receiver is specifically adapted to the needs of high-dynamics platforms such as sounding rockets, launch vehicles and re-entry capsules. It employs a specially designed tracking loop tolerating extreme accelerations and jerk. Ballistic trajectory polynomials can be loaded to support a rapid reacquisition in case of temporary signal losses. Furthermore, instantaneous-impact-point predictions are performed inside the receiver to support range-safety monitoring at the launch site. Technical Data Unless otherwise noted, the following data apply for the Phoenix-S, -XNS, and -HD receiver versions. Tracking • 12 correlator channels for GPS L1 C/A-code • 3rd order PLL with FLL assist • Signal dynamics up to 2 G / 15 G (-S/-HD) • Acquisition threshold 35 dB-Hz • Warm/cold start TTFF of 1/15 min Measurements • Low noise L1 C/A code and carrier phase (Phoenix-S: 0.4 m and 0.5 mm at 45 dB-Hz) • Range rate from Doppler and carrier phase (Phoenix-S: 8 cm/s and 2 cm/s) • Smoothed pseudo-range (0.1 m) • Carrier-to-Noise density Navigation • Single-point solution (pos 10 m, vel 0.1 m/s) • Filtered solution (1-2 m; -XNS only) • Update rates of 1 Hz (-S/-XNS) to 5 Hz (-HD) Input/Output • Two serial ports (LVTTL, 9.6-57.6 kbaud) • ASCII protocol (WinMon, NMEA) • 1PPS signal (LVTTL, 0.5 μs) • Discrete input line (lift-off-signal) • Programming pin Physical • Dimension 70 x 47 x 15 mm • Mass 20 g • Power 0.85 W Environmental • Operating temperature -20°C to +50°C • Storage temperature -30°C to +70°C • Total ionization dose >10 krad Accessories Available accessories for the Phoenix GPS receiver include • a Win-XP console program, • a light weight low-noise amplifier, • passive patch, helix and blade antennas, • an evaluation kit with housing and interface board for ground testing. Further Information Contact Markus Markgraf Deutsches Zentrum für Luftund Raumfahrt e.V. German Space Operations Center Oberpfaffenhofen 82230 Wessling, Germany Phone: +49 (8153) 28-3513 e-mail: [email protected] Disclaimer All information given in this data sheet is preliminary and subject to change without notice. Delivery of unrestricted Phoenix receivers is subject to authorization by the German Bundesamt für Wirtschaft und Ausfuhrkontrolle (BAFA).
The SGR-Ligo is SSTL’s miniaturised Space GNSS (Global Navigation Satellite System) Receiver that supports the Cubesat PC-104 standard. The SGR-Ligo is low mass, low power and delivers position, velocity and time to Low Earth orbit satellites. It uses radiation tolerant core components; supports dual antennas and supporting 24+ channels capable of tracking GPS L1 signals, with options for GLONASS G1 and Galileo E1 signals. The SGR-Ligo supports multiple interface standards including UART, CAN and I2C, and can be powered from either 3V3 or 5V spacecraft buses. The SGR-Ligo also supports the use of passive antennas for even lower power requirements. Space GNSS Receiver SGR-Ligo CHANGING THE ECONOMICS OF SPACE Position, Velocity, Time Determination for LEO Missions Cubesat PC-104 standard footprint Reduced power requirements COTS-based design BENEFITS Supports 3V3 or 5V power 1 to 2 active or passive antennas Passive antenna support 24 L1/G1/E1 channels Fast Time to First Fix Multi GNSS options FEATURES
CubeSat Kit GPSRM 1 Rev. C © Pumpkin, Inc. 2003-2014 2 of 19 July 2014 – document Rev. D CHANGELOG Rev. Date Author Comments A 20131218 AEK Initial release of hardware Rev C. B 20140120 AEK Updated to include oscilloscope captures of VARF and CLK Out signals. Included Assembly Revisions table, along with jumper settings. Added COM1 Output screen capture. C 20140210 AEK Updated to state compatibility with all members of the OEM615/OEM615V family, including dual-frequency GPS and GLONASS satellite signal tracking. D 20140721 AEK Added pin descriptions for J1 (in-circuit debugging connector), J2 (USB Debug Adapter connector), and H3 (expansion module connector). Added more codes for configurations. Clarified what is meant by “jumper.”
CubeSat Kit GPSRM 1 Rev. C © Pumpkin, Inc. 2003-2014 3 of 19 July 2014 – document Rev. D OPERATIONAL DESCRIPTION The GPSRM 1 GPS receiver adds GPS functionality to the CubeSat Kit™ (CSK) by integrating a NovAtel® OEM615-series receiver onto a CSK-compatible module. A supervisor MCU controls power and interface to the CSK bus. The interface to the supervisor MCU is via I2C. The GPSRM 1 is designed to mount directly above the combination of a CSK Motherboard (MB) + Pluggable Processor Module (PPM), at the standard inter-module distance of 0.600" (15.24mm), using a GPS antenna cable terminated in a right-angle MCX plug. This arrangement provides the necessary clearance for the GPS antenna cable's connector. In its default configuration, the GPSRM 1 utilizes the NovAtel® OEM615V-G1S-B0G-TT0-H2 GPS L1 receiver module with a 20Hz update rate and a vibration-resistant TCXO. As fitted on the GPSRM 1, these GPS receiver modules have had their COCOM limits removed / unblocked. For an additional cost, customers can request any model from the OEM615 family for use on the GPSRM 1. This includes versions with L1/L2/L2C GPS and/or L1/L2 GLONASS signal tracking. Please contact the factory for more details. Power to the GPS receiver is under the control of the PIC24E-series supervisor MCU and can switched on or off via I2C commands. Power is automatically selected from available power: either (external) USB or the CubeSat Kit bus. The OEM615 receiver's –RESET, EVENT1 and EVENT2 inputs are under the control of the supervisor MCU.3 The first serial port of the OEM615 module is normally used to communicate with the rest of the CubeSat via one of the three CubeSat Kit bus signal pairs IO.4 & IO.5, IO.16 & IO.17 or IO.32 & IO.33. This serial port can be isolated from the CubeSat Kit bus via I2C commands. The second serial port of the OEM615 module is connected to the supervisor MCU and can be used to transfer data and commands between the OEM615 module and the supervisor MCU. The third serial port of the OEM615 module – implemented as USB – is connected directly to a micro-AB USB connector. This USB connection can also power the OEM615 module. A Position Valid (PV) LED indicator from the OEM615 receiver is provided, as well as a status LED from the supervisor MCU. The 50Ω TIMEMARK (PPS) signal from the OEM615 receiver is available in one of two user-selectable forms: on an MCX jack for use with discrete RF cabling, and on the CubeSat Kit bus PPS signal. The VARF (variable frequency) signal from the OEM615 receiver is present on an MMCX jack for use with discrete RF cabling, and also (optionally) on IO.31 of the CubeSat Kit bus. An additional TX/RX debug port to the supervisor MCU is provided, to aid in supervisor MCU firmware development & debugging. Additionally, a 20-pin connector is provided as a means of connecting expansion boards (where possible) under the control of the supervisor MCU. Lastly, an MMCX connector is provided for measuring the supervisor MCU's unbuffered internal clock frequency. Particular attention has been paid to the shielding and heatsinking of the OEM615 receiver. An integrated EMC / EMI shield and heatsink covers the entire OEM615 receiver and is electrically and thermally tied to all four corner standoff locations. Special attention in the PCB design has been paid to avoid any isolated dielectric regions resulting from unconnected swatches of copper. A related module – GPSRM 2 – provides similar features and performance in a form factor designed expressly for Pumpkin’s MISC 3 bus. 2 Throughout this datasheet, the NovAtel GPS receiver will be referred to as the "OEM615." 3 The OEM615 receiver’s CAN2TX and CAN2RX signals are left unconnected.
CubeSat Kit GPSRM 1 Rev. C © Pumpkin, Inc. 2003-2014 4 of 19 July 2014 – document Rev. D ABSOLUTE MAXIMUM RATINGS Parameter Symbol Value Units Operating temperature TA -40 to +85 ºC Voltage on +5V_USB bus Voltage on +5V_SYS bus Voltage on VCC_SYS bus -0.3 to +6 V Voltage on local VCC_MCU bus -0.3 to +5.5 V PHYSICAL CHARACTERISTICS Parameter Conditions / Notes Symbol Min Typ Max Units Mass 4 With aluminum heatsink / EM shield 106 g Height of components above PCB With mating cable to MCX PPS jack 11 mm Without GPS antenna cable connected 2.75 Height of components below PCB With GPS antenna cable connected via RA MCX plug 5.5 mm PCB width 96 mm PCB length 90 mm PCB thickness Corner hole pattern matches PC/104 1.6 mm CubeSat Kit Bus Connector terminal pitch Horizontal or vertical distance to nearest terminal 2.54 mm 4 With OEM615V-G1S-B0G-TT0-H and with heatsink / EM shield fitted. Dual-band OEM615V versions may be slightly heavier.
CubeSat Kit GPSRM 1 Rev. C © Pumpkin, Inc. 2003-2014 5 of 19 July 2014 – document Rev. D SIMPLIFIED MECHANICAL LAYOUT 5 5 Dimensions in inches.
CubeSat Kit GPSRM 1 Rev. C © Pumpkin, Inc. 2003-2014 6 of 19 July 2014 – document Rev. D ELECTRICAL CHARACTERISTICS (T = 25ºC, +5V bus = +5V unless otherwise noted) Parameter Conditions / Notes Symbol Min Typ Max Units Supervisor MCU & GPS active, no antenna connected POP_SUP_GPS_LNA 1.3 W Operating power consumption Supervisor MCU active, GPS unpowered POP_SUP 25 mW Supervisor MCU & GPS active, with active antenna connected IOP_SUP_GPS_LNA 300 mA Supervisor MCU & GPS active, no antenna connected IOP_SUP_GPS 260 mA Supervisor MCU active, GPS unpowered IOP_SUP 4.5 mA Operating current 6 Supervisor MCU asleep, GPS unpowered ISLEEP 1.5 mA Supervisor MCU internal clock frequency Base frequency, can be multiplied by onboard PLL ƒCLK_MCU 7.3728 MHz USB bus current 7 Powered over USB IUSB_MAX 500 mA For +3.3V, set by R19 & R20 ITRIP_3V3_GPS TBD mA Overcurrent trip point for OEM615 For +5V, set by R15 & R16 ITRIP_+5V_GPS TBD mA Data rate through any on-board isolator (U4 & U5) 50 MHz OEM615 GPS RECEIVER ELECTRICAL CHARACTERISTICS Parameter Conditions / Notes Min Typ Max Units Impedance 50 Ω Rise & fall times 6 ns Negative pulse width 1.000 ms Amplitude (3V3_GPS = +3.3V, unterminated) 3.24 PPS Output at J7 Amplitude (3V3_GPS = +3.3V, terminated with 50Ω) 2.40 V Effect on GPS SNR of GPSRM 1's EM shield Observed SNR improvement of multiple, individual GPS satellites with GPSRM 1 EM shield present and absent, using NovAtel® receiver software. 5 dB 6 Terrestrial GPS receiver tracking a minimum of 5 satellites when active antenna with LNA is connected. 7 The OEM615's USB interface is configured at the factory as a busor self-powered device and reports a maximum current of 100mA to the attached USB host.
CubeSat Kit GPSRM 1 Rev. C © Pumpkin, Inc. 2003-2014 7 of 19 July 2014 – document Rev. D I2C CHARACTERISTICS Parameter Conditions / Notes Min Typ Max Units I2C address 7-bit I2C address 0x51 I2C clock speed 400 kHz I2C pull-up resistors No pull-up resistors are fitted to SCL_SYS or SDA_SYS ∞ Ω USB DEVICE CHARACTERISTICS Parameter Conditions / Notes Value Speed USB 2.0 compatible Full Speed (12Mbps) Vendor ID (VID) 0x09D7 Product ID (PID) 0x0100 Required driver Supplied by NovAtel
CubeSat Kit GPSRM 1 Rev. C © Pumpkin, Inc. 2003-2014 8 of 19 July 2014 – document Rev. D BLOCK DIAGRAM 3V3_GPS +5V_USB CubeSat Kit Bus Connector R9 +5V_GPS VCCB_ISO R8 VCC_MCU +5V_GPS LDO +3.3V 3V3_USB +5V_SYS +5V_USB VCC_SYS 3V3_USB 3V3_GPS +5V_GPS I_limit 5 OEM615V GPS Receiver I_limit 5 3V3_GPS LDO +3.3V VCCB_ISOVCCA_ISO Current-limited switch w/protection OFF_VCC +5V_SYS DGND R10 IO.5 IO.4 IO.17 IO.33 IO.16 IO.32 R26 R27 R28 R29 R30 R31 Rx Tx Rx End COM1 CAN External Active GPS Antenna (w/+5V LNA) Front Position PV (MCX) USB Tx R24 USB 50 Ohm +5V_USB Micro AB PPS 50 Ohm J7 (MCX) mark R25 TimeValid COM2 Tx Rx (green) EVENT1 EVENT2 -RESET VARF PIC24E Supervisor MCU SCL 3V3_MCU VCC_MCU 10k I2C Isolator J8 (MMCX) R32 SCL_SYS IO.31 SDA_SYS -RESET PCA9515A Reset Supervisor VCC_MCU SDA VCCA_ISO Enable R3 R4 I2C -RESET I/O A/D I/O UART1 I/O Tx Rx I/O & Sense & Select Program & debug Clock Out to USB Debug Adapter UART2 Tx Rx 5 6-pin FPC ICD CLKOUT 4-pin FPC J6 (MMCX) I/O EXP.[11..0] 12 Periph. Pin Select) (with Status (amber) Expansion Board +5V_SYS VBATT VBACKUP VCC_SYS
CubeSat Kit GPSRM 1 Rev. C © Pumpkin, Inc. 2003-2014 9 of 19 July 2014 – document Rev. D CubeSat Kit Bus PIN DESCRIPTIONS IO.46 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 41 43 45 47 49 51 42 44 46 48 50 52 H2 H-2X26-F IO.47 CubeSat System Bus 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 41 43 45 47 49 51 42 44 46 48 50 52 H1 H-2X26-F IO.22IO.23 IO.9 IO.5 IO.11 IO.15 IO.19 IO.21 IO.13 IO.7 IO.3 IO.1 FAULT IO.17 VREF0 IO.8 IO.10 IO.14 IO.18 IO.20 IO.12 IO.6 IO.2 IO.0 IO.4 IO.16 +5V_SYS IO.25 IO.27 IO.29 IO.35 IO.37 IO.41 IO.43 IO.45 IO.39 IO.33 IO.31 +5V_SYS +5V_SYS IO.24 IO.26 IO.28 IO.30 IO.34 IO.36 IO.38 IO.40 IO.42 IO.44 IO.32 VCC_SYS USER7 S2 S3 GND GND VCC_SYS S5 S4 S1 S0 VBATT VBATT USER6 S2 S3 GND VCC_SYS +5V_USB AGND S1 S0 S4 S5 VBACKUP VBATT VBATT USER1 VREF2 -RST_MHX -RTS_MHX -DTR_MHX RXD_MHX +5V_USB VREF1 RSVD0 PPS VBACKUP PWR_MHX USER0 SENSE -CTS_MHX -DSR_MHX TXD_MHX -RESET SDA_SYS SCL_SYS RSVD1 OFF_VCC USER2 USER4 USER3 USER5 USER8 USER10 USER9 USER11 CubeSat Kit Bus PIN DESCRIPTIONS – I/O Name Pin I/O Description IO.0 H1.24 Not connected. IO.1 H1.23 Not connected. IO.2 H1.22 Not connected. IO.3 H1.21 Not connected. IO.4 H1.20 I Serial input to the OEM615 receiver’s RX1D pin. This input receives data from IO.4 if/when jumper8 R29 is fitted. Typically serial data UTX0 from the PPM processor. IO.5 H1.19 O Serial output from the OEM615 receiver’s TX1D pin. This output sends data to IO.5 if/when jumper R26 is fitted. Typically serial data URX0 to the PPM processor. IO.6 H1.18 Not connected. IO.7 H1.17 Not connected. IO.8 H1.16 Not connected. IO.9 H1.15 Not connected. IO.10 H1.14 Not connected. IO.11 H1.13 Not connected. IO.12 H1.12 Not connected. IO.13 H1.11 Not connected. IO.14 H1.10 Not connected. IO.15 H1.9 Not connected. IO.16 H1.8 I Serial input to the OEM615 receiver’s RX1D pin. This input receives data from IO.16 if/when jumper R30 is fitted. Typically serial output from a module to the OEM615. IO.17 H1.7 O Serial output from the OEM615 receiver’s TX1D pin. This output sends data to IO.17 if/when jumper R27 is fitted. Typically serial input to a module from the OEM615. IO.18 H1.6 Not connected. IO.19 H1.5 Not connected. IO.20 H1.4 Not connected. IO.21 H1.3 Not connected. IO.22 H1.2 Not connected. IO.23 H1.1 Not connected. 8 On the GPSRM 1, all jumpers are implemented as zero-Ohm resistors soldered in place at time of assembly at the factory.
CubeSat Kit GPSRM 1 Rev. C © Pumpkin, Inc. 2003-2014 10 of 19 July 2014 – document Rev. D IO.24 H2.24 Not connected. IO.25 H2.23 Not connected. IO.26 H2.22 Not connected. IO.27 H2.21 Not connected. IO.28 H2.20 Not connected. IO.29 H2.19 Not connected. IO.30 H2.18 Not connected. IO.31 H2.17 O Variable-frequency output from the OEM615 receiver’s VARF pin. This output places the VARF square wave on IO.31 if/when jumper R32 is fitted. Typically used by modules desiring a high-accuracy clock signal. IO.32 H2.16 I Serial input to the OEM615 receiver’s RX1D pin. This input receives data from IO.32 if/when jumper R31 is fitted. Typically serial output from a module to the OEM615. IO.33 H2.15 O Serial output from the OEM615 receiver’s TX1D pin. This output sends data to IO.33 if/when jumper R28 is fitted. Typically serial input to a module from the OEM615. IO.34 H2.14 Not connected. IO.35 H2.13 Not connected. IO.36 H2.12 Not connected. IO.37 H2.11 Not connected. IO.38 H2.10 Not connected. IO.39 H2.9 Not connected. IO.40 H2.8 Not connected. IO.41 H2.7 Not connected. IO.42 H2.6 Not connected. IO.43 H2.5 Not connected. IO.44 H2.4 Not connected. IO.45 H2.3 Not connected. IO.46 H2.2 Not connected. IO.47 H2.1 Not connected. CubeSat Kit Bus PIN DESCRIPTIONS – Analog References Name Pin I/O Description VREF0 H1.26 Not connected. VREF1 H1.28 Not connected. VREF2 H1.30 Not connected. CubeSat Kit Bus PIN DESCRIPTIONS – Reserved Name Pin I/O Description RSVD0 H1.44 – Not connected. RSVD1 H1.45 – Not connected. CubeSat Kit Bus PIN DESCRIPTIONS – I2C Bus Name Pin I/O Description SDA_SYS H1.41 I/O I2C data. To/from supervisor MCU (an I2C slave device) via a PCA9515A I2C isolator. Typically from the PPM processor. SCL_SYS H1.43 I I2C clock. To supervisor MCU (an I2C slave device) via a PCA9515A I2C isolator. Typically from the PPM processor.
CubeSat Kit GPSRM 1 Rev. C © Pumpkin, Inc. 2003-2014 11 of 19 July 2014 – document Rev. D CubeSat Kit Bus PIN DESCRIPTIONS – Control & Status Name Pin I/O Description -FAULT H1.25 Not connected. SENSE H1.27 Not connected. -RESET H1.29 I/O Input to and/or output from reset supervisor controlling supervisor MCU. Functionality depends on resistors R3 & R4. OFF_VCC H1.31 I When resistor R10 is fitted and no USB power is present, an active signal on this pin will disable VCC_MCU power to the supervisor MCU. PPS9 H1.46 O PPS. From the OEM615 receiver’s TIMEMARK (PPS) output. This output is present whenever the OEM615 is powered and operating. 50Ω impedance. CubeSat Kit Bus PIN DESCRIPTIONS – RBF and Separation Switches Name Pin I/O Description S0 H2.33 H2.34 Not connected. S1 H2.35 H2.36 Not connected. S2 H2.37 H2.38 Not connected. S3 H2.39 H2.40 Not connected. S4 H2.41 H2.42 Not connected. S5 H2.43 H2.44 Not connected. CubeSat Kit Bus PIN DESCRIPTIONS – Power Name Pin I/O Description VBATT H2.45 H2.46 I Battery voltage. EPS-dependent. Typically +7V to +10V. To expansion connector H3.5 & H3.6 only. +5V_USB H1.32 I/O +5V USB power. From USB host. +5V_SYS H2.25 H2.26 I +5V system power. PWR_MHX H1.33 Not connected. VBACKUP H1.42 I Battery backup voltage. To expansion connector H3.8 only. VCC_SYS H2.27 H2.28 I VCC System power. Assumed to be +3.3V. AGND H2.31 Not connected. DGND H2.29 H2.30 H2.32 – Digital ground. CubeSat Kit Bus PIN DESCRIPTIONS – Transceiver Interface Name Pin I/O Description -RST_MHX H1.34 Not connected. -CTS_MHX H1.35 Not connected. -RTS_MHX H1.36 Not connected. -DSR_MHX H1.37 Not connected. -DTR_MHX H1.38 Not connected. TXD_MHX H1.39 Not connected. RXD_MHX H1.40 Not connected. 9 This signal was formerly called RSRVD2 and was reserved.
CubeSat Kit GPSRM 1 Rev. C © Pumpkin, Inc. 2003-2014 18 of 19 July 2014 – document Rev. D Jumpers VARF Configuration Description Example Host Fitted Omitted A VARF is not mapped to CSK Bus. PPMs or other hosts that cannot effectively utilize VARF when mapped to IO.31. R32 B VARF is mapped to IO.31. PPMs or other hosts that have facilities to utilize a programmable clock signal on IO.31. R32 CSK Bus Mapping: -RESET The GPSRM 1 has its own independent reset supervisor (U2). The reset supervisor can be configured to interact with the CubeSat Kit Bus –RESET signal as an input to and/or an output. Four different configurations are supported via the selective jumpers implemented as zero-Ohm resistors R3 and R4: Jumpers -RESET Configuration Description Resultant Behavior Fitted Omitted A Local reset supervisor U2 is not used, GPSRM 1 is completely disconnected from –RESET. Supervisor MCU utilizes only its own on-chip BOR/POR circuitry to enforce clean (re-)starts. Not recommended. R3, R4 B GPSRM 1's local reset supervisor U2 resets Supervisor MCU and can be triggered via –RESET. GPSRM 1 can be reset via local reset supervisor U2 and external –RESET signal. R4 R3 C Local reset supervisor U2 is not used, GPSRM 1 can drive –RESET signal. Supervisor MCU utilizes only its own on-chip BOR/POR circuitry to enforce clean (re-)starts. GPSRM 1 can reset the CubeSat Kit Bus by forcing local signal –FORCE_RESET low. Not recommended. R3 R4 D GPSRM 1's local reset supervisor U2 resets Supervisor MCU and can be triggered via –RESET. GPSRM 1 can drive –RESET signal. GPSRM 1 can be reset via local reset supervisor U2 and external –RESET signal. GPSRM 1 can also reset the CubeSat Kit Bus by forcing local signal –FORCE_RESET low – this will in turn force a GPSRM 1 reset. Use with caution. R3, R4 Assembly Revisions As a consequence of the various jumper-driven configurations outlined above, end-users may specify an assembly revision when ordering their GPSRM 1. A binary code is utilized, as shown below, with the resulting assembly revision numbers shown in decimal format, with powers-of-2 weights from left to right: ASSY REV R9 or R8 R32 R3 R4 R28 &R31 R27 &R30 R26 &R29 Typical Application 8 R9 - - + - - - Sole interface to Supervisor MCU is via I2C. 9 R9 - - + - - + PPM Ax, OEM615 COM1 on IO.5 & IO.4. 10 R9 - - + - + - PPM Dx, OEM615 COM1 on IO.17 & IO.16. 41 R9 + - + - - + PPM Ax, OEM615 COM1 on IO.5 & IO.4, additional module utilizes VARF on IO.31. 44 R9 + - + + - - PPM B1, OEM615 COM1 on IO.33 & IO.32, additional module utilizes VARF on IO.31. 73 R8 - - + - - + Customer PPM with 5V I/O, OEM615 COM1 on IO.5 & IO.4. Use with alternate GPS Receivers Bare COCOM-unblocked GPS receiver rated for space use can cost thousands of dollars. If/when an alternate GPS receiver has a compatible pinout and connectors, then it may be possible to use with the GPSRM 1 in place of the OEM615 receiver for ground-based development and test. The following caveats must be observed: 1. The integrated heatsink / RFI cover will likely not fit and should not be used. 2. All of the alternate GPS receiver module's I/O must match or be a subset of those of the OEM615 receiver series. 3. No part of the alternate GPS receiver may touch the GPSRM 1 PCB. 4. The protection circuits of the GPSRM 1 may not be compatible with those of the alternate GPS receiver. For alternate GPS receivers that are powered exclusively via +3.3V on pins 3 and 4 of the 20-pin header GPS1,
CubeSat Kit GPSRM 1 Rev. C © Pumpkin, Inc. 2003-2014 19 of 19 July 2014 – document Rev. D 1. Remove and do not plug in any USB cables to connector J3. 2. Fit two shorting jumpers on J5: 1-3 and 2-4.12 3. If necessary, prevent the existing +5V and +3.3V power on the header GPS1 from reaching pins 1 and 2 of the alternate GPS receiver. This may require cutting the connector pins on the alternate GPS receiver. This will feed the GPSRM 1's local +3.3V supply to pins 3 and 4 of the 20-pin header GPS1 for use with a alternate, compatible GPS receiver (i.e., one other than the OEM615 receiver). A sample, low-cost GPS receiver that can be used in this manner is the Royaltek REB-21R, in its 3.3V TTL & RS-232 output configuration.13 TRADEMARKS The following are Pumpkin trademarks. All other names are the property of their respective owners. • Pumpkin™and the Pumpkin logo • Salvo™ and the Salvo logo • MISC™ • CubeSat Kit™ and the CubeSat Kit logo DISCLAIMER PUMPKIN RESERVES THE RIGHT TO MAKE ANY CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO CORRECT ERRORS AND IMPROVE RELIABILITY, FUNCTION, APPEARANCE OR DESIGN. PUMPKIN DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. 744 Naples Street San Francisco, CA 94112 USA tel: (415) 584-6360 fax: (415) 585-7948 web: http://www.pumpkininc.com/ email: [email protected] web: http://www.cubesatkit.com/ email: [email protected] 12 When installed, these jumpers are parallel to the H1 and H2 CubeSat Kit Bus connectors. 13 The particular model tested (with a datecode of 2003, found at an electronics surplus store for under $10) had to have its rightangle MCX jack removed and replaced with a straight MCX plug on the opposite side of the PCB so as to be able to mate to the 20-pin connector on the GPSRM 1 PCB.
APPENDIX C. VENUS 838FLPX RECEIVER SIMULATIONS Figure C.1: Venus 838FLPx-SPC Simulation Results Figure C.2: Venus 838FLPx-SPC Simulation Results Figure C.3: Venus 838FLPx-SPC Simulation Results 63
Figure C.4: Venus 838FLPx-SPC Simulation Results Figure C.5: Venus 838FLPx-SPC Simulation Results Figure C.6: Venus 838FLPx-SPC Simulation Results
Figure C.7: Venus 838FLPx-SPC Simulation Results Figure C.8: Venus 838FLPx-SPC Simulation Results Figure C.9: Venus 838FLPx-SPC Simulation Results
Figure C.10: Venus 838FLPx-SPC Simulation Results
APPENDIX D. OEM719L BUDGET AND COCOM END-USE STATEMENT 67
ORBITAL-GNSS S.A.S.U. - 1 esplanade Compans Caffarelli – 31000 TOULOUSE - France Tel: +33 562 150 437 – Fax: +33 562 150 444 – E-mail: [email protected] SIRET 822276911 00010 – TVA Intracommunautaire FR 77 822276911 Página 1 de 4 Toulouse, 22 de enero de 2020 UNIVERSITAT POLITÈCNICA DE CATALUNYA EETAC - Escola d'Enginyeria de Telecomunicació i Aeroespacial de Castelldefels Office C3-115 C/Esteve Terradas, 7 08860 - Castelldefels At. Jordi L. Gutiérrez En referencia a su petición por medio del Sr. Alejandro Guerra Mentruit le sometemos a su amable consideración el presupuesto solicitado : PRESUPUESTO OEM719-H Descripción Ctd. Precio unidad 1 Total 1 OEM719-GSN-LNN-TNN-H *CG* GPS, L1, Single Point+DGPS PNT, 20 Hz Data Output Rate, High Speed Includes GLIDE & RAIM and tracks SBAS/QZSS/LBand. CEP - Canadian Export Permit2 TOTAL por unidad OEM719 OEM719-GSN-LNN-TNN-H *CG* GPS, L1, Single Point+DGPS PNT, 20 Hz Data Output Rate, High Speed Includes GLIDE & RAIM and tracks SBAS/QZSS/LBand. CEP - Canadian Export Permit2 TOTAL por unidad OEM719 OEM719-GSN-LNN-TNN-H *CG* GPS, L1, Single Point+DGPS PNT, 20 Hz Data Output Rate, High Speed Includes GLIDE & RAIM and tracks SBAS/QZSS/LBand. CEP - Canadian Export Permit2 TOTAL por unidad OEM719 1 1 1 5 1 5 11 1 11 1 733.00 2 382.00 4 115.00 --- 1 567.00 2 382.00 2 043.40 --- 1 516.00 2 382.00 1 732.55 1 733.00 2 382.00 4 115.00 --- 7 835.00 2 382.00 10 217.00 --- 16 676.00 2 382.00 19 058.00
ORBITAL-GNSS S.A.S.U. - 1 esplanade Compans Caffarelli – 31000 TOULOUSE - France Tel: +33 562 150 437 – Fax: +33 562 150 444 – E-mail: [email protected] SIRET 822276911 00010 – TVA Intracommunautaire FR 77 822276911 Página 2 de 4 OEM719-GSN-LNN-TNN-H *CG* GPS, L1, Single Point+DGPS PNT, 20 Hz Data Output Rate, High Speed Includes GLIDE & RAIM and tracks SBAS/QZSS/LBand. CEP - Canadian Export Permit2 TOTAL por unidad OEM719 OEM719-GSN-LNN-TNN-H *CG* GPS, L1, Single Point+DGPS PNT, 20 Hz Data Output Rate, High Speed Includes GLIDE & RAIM and tracks SBAS/QZSS/LBand. CEP - Canadian Export Permit2 TOTAL por unidad OEM719 51 1 51 101 1 101 --- 1 397.00 2 382.00 1 443.71 --- 1 399.00 2 382.00 1 422.58 --- 71 247.00 2 382.00 73 629.00 --- 141 299.00 2 382.00 143 681.00 TOTAL EN €1 SU ELECCIÓN 1Precio en € e I.V.A. no incluido *CG* Requiere COCOM Limits Removal (en el caso de NovAtel es la eliminación del límite de la velocidad) 2El CEP tiene una validez de dos años a partir de la fecha de emisión. Condiciones : Las condiciones de venta aplicables son las descritas por NovAtel Inc., con base en Alberta, Canadá, en el enlace http://www.novatel.com/where-to-buy/sales-offices/standard-terms-and-conditions-of-sales/ con las modificaciones siguientes dónde procede : Todos los precios son Portes Pagados dentro la Península Ibérica e incluyen el embalaje comercial estándar, flete internacional, los seguros, los aranceles, gastos aduaneros y comisiones, gastos bancarios, transportes internos. Los precios no incluyen el IVA ni impuestos locales. La orden de COCOM Removal requiere de un End User Statement (Declaración de Uso) en idioma inglés dirigida al fabricante en papel con membrete de la institución. Esta Declaración de uso ha de enviarse en original a nuestra dirección y por email en formato PDF junto con el pedido formal y el comprobante del pago. Se necesita de estos tres documentos para la gestión del pedido. El plazo de entrega se estima de 4 a 6 semanas desde el momento de recepción de los tres documentos indicados más arriba y dependerá de la gestión del Gobierno de Canadá. Validez de la oferta : 15 días. Condiciones de pago: - Por la naturaleza de este pedido se requiere de prepago junto con su orden de compra. La cantidad no es reembolsable. - Para cantidades superiores a los 25000€ la forma de pago es a convenir. Efectuar los pagos a la BNP PARIBAS Nº de cuenta FR7630004015700001010051084 .