Implementation of a long range radio-link system for femto-satellites in very Low Earth Orbit

TREBALL FI DE CARRERA TÍTOL DEL TFC: Implementació d’un radio-enllaç de llarg abast per a femto-satèl·lits en òrbita molt baixa TITULACIÓ: Enginyeria Tècnica Aeronàutica, especialitat Aeronavegació AUTOR: Sara Izquierdo Jiménez DIRECTOR: Joshua Tristancho Martínez DATA: 05 de Novembre de 2013 Título: Implementación de un sistema de radio-enlace de largo alcance para femto-satélites en órbitas muy bajas. Autor: Sara Izquierdo Jiménez Director: Joshua Tristancho Martínez Fecha: 29 de Octubre de 2013 Resumen Este Trabajo Final de Carrera (TFC) estudia algunas implementaciones reales de radio-enlaces de largo alcance para un femto-satélite (masa inferior a 100 gramos) que estará en una órbita terrestre baja en 250 km y que durará unas pocas semanas de vuelo. Este satélite (El WikiSat) no lleva paneles solares y se alimenta de una batería. Por ello, el sistema de comunicaciones debe estar optimizado, ser eficiente, pesar muy poco y tener margen de potencia. Este satélite fue diseñado por estudiantes. El diseño original del WikiSat no cumple con algunos de los requerimientos por lo que se propone usar dispositivos comercialmente disponibles de la tienda o COTS que formen un sistema completo de radioenlace o implementación como son el transceptor nRF24L01, el amplificador PA2423L, el módulo 9XTend, el modulador de vídeo 10MW, el amplificador PA5359A o el módulo NTX2. Estos componentes utilizan tecnologías que permiten una alta integración, un buen rendimiento energético y de transmisión. El punto clave en el diseño será alimentar el módulo de radio directamente de la batería sin ninguna rectificación de voltaje usando una arquitectura distribuida para evitar desperdiciar energía en la transformación. La implementación final será parte de la siguiente versión del WikiSat. Algunos requerimientos son impuestos adicionalmente por el diseño del satélite que han realizado otros. El autor deberá analizar su viabilidad y proponer mejoras. Palabras clave: Radio-enlace, Femto-satélite, Órbitas muy bajas, Bajo coste Title: Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit. Author: Sara Izquierdo Jiménez Director: Joshua Tristancho Martínez Date: October, 29th 2013 Overview This Final Bachelor Work (TFC) studies some real implementations of long range radio-link systems for a femtosatellite (mass lower than 100 grams) in very Low Earth Orbit in 250 km and few weeks of flight. The satellite (The WikiSat) has not solar panels and is supplied by a battery. For this reason, the communication system should be optimized to be efficient, light with enough power margins. This satellite was designed by students that do not meet some requirements. The author evaluates some implementations based on Commercial off-the-shelf (COTS) devices. Some of them are a whole communications system and some are a group of components like the nRF24L01 transceiver, the PA2423L power amplifier, the 9XTend radio module, the 10MW video modulator, the PA5359A power amplifier or the NTX2 radio module. Those devices are based on technologies that allow a high level of integration, a good electrical power and radiation performance. The key point in the design will to supply the radio module directly from the battery without any voltage rectification with a distributed schema to avoid energy waste in the transformation. The best implementation will be part of the future WikiSat version. Some requirements are imposed in addition by the satellite design performed by others. Keywords: Radio-link, Femtosatellite, Low Earth Orbit, Low Cost 5 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit INDEX ACRONYMS, ABBREVIATIONS AND DEFINITIONS .................................... 11 INTRODUCTION .............................................................................................. 13 CHAPTER 1. STATE OF THE ART .............................................................. 17 1.1 Origin of this satellite .............................................................................................. 17 1.2 Femtosatellites ......................................................................................................... 17 1.2.1 Examples of Femtosatellites ................................................................................. 18 1.2.2 WikiSat description ............................................................................................... 18 1.3 WikiSat Team ............................................................................................................ 19 1.4 Micro-Electro Mechanical Systems - MEMS technology ..................................... 20 1.5 Printed Circuit Board – PCB technology ............................................................... 22 1.6 Surface Mounted Device - SMD technology .......................................................... 23 CHAPTER 2. SYSTEM REQUIREMENTS .................................................... 25 2.1 System requirements .............................................................................................. 25 2.2 High level requirements .......................................................................................... 25 2.3 Low level requirements ........................................................................................... 25 CHAPTER 3. CASES OF STUDY ................................................................. 27 3.1 Description of the proposed implementations ..................................................... 27 3.1.1 Nordic nRF24L01P and SiGe PA2423L ............................................................... 27 3.1.2 FPV 10MW and Ku PA 5359 implementation ...................................................... 28 3.1.3 Digi 9Xtend implementation .................................................................................. 29 3.1.4 Radiometrix NTX2 implementation ....................................................................... 29 3.2 Comparison of the implementations ..................................................................... 30 CHAPTER 4. SPECIFICATIONS .................................................................. 33 4.1 Link budget ............................................................................................................... 33 4.2 Energy budget .......................................................................................................... 36 4.2.1 Power budget........................................................................................................ 37 4.2.2 Power source ........................................................................................................ 38 4.3 Bill of materials ........................................................................................................ 39 4.4 Digi 9Xtend test ........................................................................................................ 39 4.4.1 Antenna manufacturing ........................................................................................ 40 4.4.2 Monopole antenna certification (902 MHz SMA) .................................................. 40 4.4.3 Antenna validation ................................................................................................ 42 4.4.4 Module test ........................................................................................................... 42 INDEX 6 CHAPTER 5. CONCLUSIONS ...................................................................... 45 5.1 General conclusions ................................................................................................ 45 5.2 Future work ............................................................................................................... 46 5.3 Environmental impact ............................................................................................. 46 CHAPTER 6. BIBLIOGRAPHY ..................................................................... 47 6.1 Argentdata SSTV camera datasheet ...................................................................... 54 6.2 FPV 10 mW AV transmitter datasheet .................................................................... 56 6.3 Kuhne PA5359A power amplifier datasheet .......................................................... 57 6.4 NORDIC nRF24L01 transceiver datasheet ............................................................ 58 6.5 SiGe PA2423L power amplifier datasheet ............................................................. 74 6.6 Digi 9Xtend RF module datasheet .......................................................................... 81 6.7 Radiometrix NTX2 transceiver datasheet .............................................................. 83 6.8 SMA connector family ............................................................................................. 95 7 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit LIST OF FIGURES Figure 1 – Satellite classification as a function of mass ................................... 13 Figure 2 – Some examples of femtosatellite designs. Source: Investigación y Ciencia ...................................................................................................... 18 Figure 3 – PCB used for the Launch05 and a WikiSat v4.0 prototype. Source: Joshua Tristancho ..................................................................................... 23 Figure 4 - LCC devices: u-blox NEO6M GPS (a) Source: u-blox and TOSHIBA TCM8230 camera (b) Source: TOSHIBA .................................................. 24 Figure 5 – Femtosatellite axes (a) and radiation pattern (b). Source: Enric Fernandez ................................................................................................. 27 Figure 6 – FPV 10MW implementation (Source: Argent) with Power Amplifier. Source: Kuhne-electronic .......................................................................... 28 Figure 7 – Digi 9Xtend implementation. Source: Digi ....................................... 29 Figure 8 – Radiometrix NTX2 implementation. Source: Radiometrix ............... 30 Figure 9 – Femtosatellite diagram block and link budget for the original nRF24L01P configuration. Source: Enric Fernandez ................................ 34 Figure 10 – Femtosatellite diagram block and link budget for the 10MW configuration. Adapted from: Enric Fernandez .......................................... 35 Figure 11 – Femtosatellite diagram block and link budget for the 9XTend configuration. Adapted from: Enric Fernandez .......................................... 35 Figure 12 – Femtosatellite diagram block and link budget for the NTX2 configuration. Adapted from: Enric Fernandez .......................................... 36 Figure 13 – Voltage regulation diagram blocks: distributed strategy (a) and centralized strategy (b). ............................................................................. 37 Figure 14 – 902 MHz lambda/4 antenna manufacturing ................................... 40 Figure 15 – Antenna A. Best frequency 905.882 MHz with -9.7 dB and SWR 1.97 ........................................................................................................... 41 Figure 16 – Antenna B. Best frequency 904.329 MHz with -9.5 dB and SWR 2.01. Worst frequency 922.91 MHz with -9.0 dB and SWR 2.11 ............... 41 Figure 17 – Early radio-link test. NEO-6M GPS->9XTend (a) and 9XTend- >FTDI (b) ................................................................................................... 43 9 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit LIST OF TABLES Table 1 – Performance comparison ................................................................. 31 Table 2 – Link-budget summary (Four cases) .................................................. 38 Table 3 – Mass and cost budget (Four cases) ................................................. 39 INTRODUCTION 16 Distribution of this work This work is distributed in five chapters detailed as follows: First chapter is an introduction to the State of the Art of femtosatellites, the WikiSat Space Program and finally a state of the art of technologies that are involved in this work. Second chapter has an extract of requirements that are related with the telecommunications system. These requirements are the reference to evaluate if a implementation are better than other. Third chapter presents four real implementations proposed inside the WikiSat team that are based on available components in the market (COTS) for the femtosatellite communications system. Fourth chapter presents several specifications: contains a series of budgets, calculations of the minimum performances for the communication system in every case and comparing the three other implementations with the current WikiSat design. Fifth chapter has the conclusions of all work, the future work and the environmental impact. Finally, there is the bibliography and the annexes with datasheets and other relevant issues. 17 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit CHAPTER 1. STATE OF THE ART This chapter is an introduction to the State of the Art of femtosatellites, the WikiSat Space Program and finally a state of the art of technologies that are involved in this work. 1.1 Origin of this satellite The origin and reason of the development of the satellite finds it in a contest of universal level known as N-Prize, born at 2008. It consists in a challenge to launch an impossibly small satellite into orbit on a ludicrously small budget, for a pitifully small cash prize. The N-Prize Challenge is intended to encourage creativity, originality and inventiveness in the face of severe odds and impossible financial restrictions for continue having access to the space through a much cheaper form. The participation is aimed at amateurs, enthusiasts, would-be boffins, foolhardy optimists and individuals or organizations connected with aerospace and other relevant industries. The challenge raises by the N-Prize is to put into orbit around the Earth a satellite with a mass of between 9.99 and 19.99 grams, and to prove that it has completed at least 9 orbits. The most important, nevertheless, is that the budget of the launch (including the vehicle of launch, all the equipment of non-reusable hardware of launch required and the propellant) should be minor than 1,200€. To opt for the prizes, the win team should complete the challenge before of 19:19:09 (GMT) on September 19 th , 2013. The prize for the win team was 12,000€. None team won the prize. 1.2 Femtosatellites The satellite, called WikiSat, the one that will include the radio-link system should have ales than 20 grams mass due to the restrictive rules of the N-Prize contest, thus it enter in the femtosatellite category, since according to international classification of satellites depend it of the mass, ‘femtosatellite’ is that one that it have a maximum mass of 100 grams. Femtosatellites are tiny satellites that contains of all functions of a conventional satellite. It should be able to realize the same mission assignments that are realized by the commercial satellites of navigation, communication and observation of the Earth. The principal advantages that femtosatellites present with regard to the other satellites are that the seconds have at least 100 times more mass, they are more expensive and voluminous, besides that they require a development time of order of years because the use of certificate components for the space flights and environmental testing that are much expensive. Technology of femtosatellite is relatively new, since only a pair of years ago that it has started its development by several organizations around the world. It is intended to be used at applications and missions where required big speed of CHAPTER 1. STATE OF THE ART 18 actuation, for example to realize observations in a zone dejected for a recent disaster. In Spain we can find this type of developments through a group of investigators belonging to the Polytechnic University of Catalonia that, as a whole with investigators of Institute to the Technological Development and the Innovation in the Communications (IDeTIC) of Palmas de Gran Canaria University, they have already achieved to prove this system of launch of low cost to put in orbit femtosatellites. 1.2.1 Examples of Femtosatellites There are no femtosatellites in orbit but few universities have developed some prototypes. From the Investigación y Ciencia magazine, we can see four of these prototypes presented in Figure 2. • PCBSat, not shown, designed by Barnhart [9] in 2007 • PocketQub, see figure 2a, designed by Twiggs, a cube standard • RyeFemSat, see figure 2b, designed by Kumar [4] in 2008 • KickSat, see figure 2c, designed by Zac Manchester [5] in 2010 • WikiSat, see figure 2d, designed by Joshua Tristancho [8] in 2010 Figure 2 – Some examples of femtosatellite designs. Source: Investigación y Ciencia 1.2.2 WikiSat description The satellite where we want to implement our radio-link is the so called WikiSat. It is a Satellite-on-a-board that achieves to carry out the challenge of the low cost and low mass. The structure of the satellite is a single PCB whose finality is to hold four arrays of ceramic antenna. This antenna configuration was proposed by Fernandez-Murcia in [14]. The PCB board works as a passive thermal control subsystem. The satellite has an Inertial Measurement Unit (IMU) designed originally by Bardolet in [15]. Components are connected through an I 2 C bus to the Main Control Unit (MCU). The use of same IMU for satellite and launcher trajectory control was proposed by Tristancho in [16] who proposes the design of a launcher and the satellite in the same design cycle for a given space mission. This is the meaning of the so called Space Payload Paradigm, to design everything around the payload, including the launcher and the ground station network if required. The use of this kind of payload will reduce the space access and will increase the periodicity of small launches. A large number of satellites can be sent in the same event, i.e. swarms of these satellites can record the same phenomena from different points of view; distributing the work load when they are coordinated. But all of this is not feasible if all the subsystems are integrated in a so low mass budget and for this reason, some technologies such as Micro- 19 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit Electro-Mechanical Systems (MEMS) and Surface Mounted Technology (SMT) is required. In addition, regarding communications, the antenna should fit inside this small budget as well. From elemental physics [10] the antenna size depends on the working frequency. The Free Space Path Lost decreases in a logarithmic way there by, the transmit power increases with a power of four of the frequency. The frequency used in the original WikiSat design was 2.4 GHz, extensively used for applications of ground short distance. This frequency was used in Low Earth Orbit, see [11, 12, 13] but in the case of the WikiSat, a power amplifier and a high gain antenna will be required for download communication system. The wave length is about few centimeters and few watts are required for a LEO range. The antenna establishes the limit of the size of the satellite, while the transmit power and the mission schedule establishes the electrical power capacity. This satellite has a mass less than 20 grams as stated by the N-Prize rules. The satellite will control all the parts of the mission: the rocket, the ignition of every stage, the trajectory, the injection and finally the mission itself. That way, repeated components are avoided. The satellite will send all the harvested information through a downlink, mainly HD pictures from a location of the Earth programmed before the launch. The satellite was designed to work as a constellation or swarms. The launcher is designed to inject four or six femtosatellite at the time and launcher can be repeated every few hours in order to reduce the revisiting time. The launcher provides an initial altitude and later the orbital commanded by the satellite. This rocket is called WikiLauncher and is an autonomous vehicle with a configuration of Rockoon, a combination of a balloon and a rocket. Starting from a high altitude balloon, first stage reaches the apogee of 250 km whereas the second stage accelerates until the orbital speed of 7.2 km/s. This launch takes about 4 hours since the mission is established, for this reason this platform is suitable for Space Responsive missions. The satellite is dedicated to a single mission (like a disaster) and is only send when the epicenter coordinates is known. Current approach is somehow based on surveillance satellites that are wasting an orbit until the catastrophe happens. This kind of satellites, due to the very low Earth orbit stays for one week then reenters in the atmosphere and burned, letting the orbit free. 1.3 WikiSat Team The team formed by investigators of UPC and IDeTIC is called WikiSat (where femtosatellite catches the name) and pretends to develop and launch femtosatellites of low cost for fast display. The system of launch was developed by the UPC, while the IDeTIC, for your part, has developed the subsystems of telecommunication used by the satellite and ground station, as well as the modeling of the diverse antennas used. These systems permit recover the reusable elements of the launcher besides to permit the reception and monitoring of its parameters during the flight. The project is directed by Professor Joshua CHAPTER 1. STATE OF THE ART 20 Tristancho, of Engineering of Telecommunication and Aerospace of Castelldefels School (EETAC) of UPC. By the part of the IDeTIC, the leadership corresponds to the Dr. Rafael Pérez Jiménez, Director of IDeTIC, and expert at advanced communications. Thus, WikiSat represents an official team of the N-Prize contest. The WikiSat Space Program pretends to implement a low-cost femtosatellite that fits the NPrize rules. The team stated that the cost 2 of a Disaster Management mission is about 30,000€ suitable for poor countries, small enterprises and science applications. The satellite is designed in a free PCB tool called Eagle PCB 3 where the client will include their surface mounted payload only; they do not have to worry about others issues like power supply, switching or download because satellite does. The mission can be designed by any amateur people thanks to a free open source tool 4 called Moon2.0. Quality design will not depend on the cost of the designing tools. 1.4 Micro-Electro Mechanical Systems - MEMS technology The main improvement for femtosatellites is using Micro-Electromechanical Systems (MEMS) that is a technology that is defined [3] as miniaturized mechanical and electro-mechanical elements (i.e., devices and structures) that are made using the techniques of micro-fabrication, and these are available in the domestic market. These components should be validated for space use. Many of them can be used in hard conditions like our femtosatellite is going to resist. The critical physical dimensions of MEMS devices can vary from well below one micron on the lower end of the dimensional spectrum, to several millimeters. Likewise, the types of MEMS devices can vary from relatively simple structures having no moving elements, to extremely complex electromechanical systems with multiple moving elements and controlled by integrated microelectronics. The one main criterion of MEMS is that there are at least some elements having some sort of mechanical functionality whether or not these elements can move. These components should be validated for space use. Many of them can be used in hard conditions like our femtosatellite is going to resist 5 in the nearspace environment. The functional elements of MEMS are miniaturized structures, sensors, actuators, and microelectronics, and the most notable (and perhaps most interesting) elements are the microsensors and microactuators, which are categorized as “transducers” (i.e., devices that convert energy from one form to another). The performance of MEMS devices are exceptional, and their method of production leverages the same batch fabrication techniques used in the 2 http://code.google.com/p/moon-20/wiki/LowCost_Space_Access 3 http://www.cadsoftusa.com/eagle-pcb-design-software/ 4 http://code.google.com/p/moon-20/downloads/list 5 https://www.mems-exchange.org/MEMS/what-is.html 21 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit integrated circuit industry, meaning a low per device production costs. Consequently, it is possible achieve stellar device performance at a low cost. The MEMS technologies have a quality called "heterogeneous integration", meaning that it can be merged with microelectronics, photonics, nanotechnology, and more others. This quality is important because the real potential of MEMS starts to become fulfilled when it can all be merged onto a common silicon substrate along with integrated circuits (i.e., microelectronics). While electronics are fabricated using integrated circuit (IC) process sequences, the micromechanical components are fabricated using compatible "micromachining" processes that selectively etch away parts of the silicon wafer or add new structural layers to form the mechanical and electromechanical devices. There are numerous possible applications for MEMS and Nanotechnology 6 . A few applications of current interest are: 1.3.1 Biotechnology For example 7 , the Polymerase Chain Reaction (PCR) microsystems for DNA amplification and identification, enzyme linked immunosorbent assay (ELISA), capillary electrophoresis, electroporation, micromachined Scanning Tunneling Microscopes (STMs), biochips for detection of hazardous chemical and biological agents, and microsystems for high-throughput drug screening and selection. 1.3.2 Communications The main beneficiary from the advent of RF-MEMS technology 8 is high frequency circuits. If they are made using MEMS and Nanotechnology, the electrical components (such as inductors and tunable capacitors) can be improved significantly compared to their integrated counterparts. With the integration of such components, we achieve reduce the total circuit area, power consumption and cost, while the performance of communication circuits will be improved. Of the other hand, the mechanical switch is a key component with huge potential in various RF and microwave circuits. The demonstrated samples of mechanical switches have quality factors much higher than anything previously available. Another successful application of RF-MEMS is in resonators as mechanical filters for communication circuits. 1.3.3 Inertial Sensing MEMS technology has made it possible to integrate the accelerometer and electronics onto a single silicon chip at a cost of only a few dollars 9 . These MEMS accelerometers are much smaller, more functional, lighter, more reliable, and are produced for a fraction of the cost of the conventional macroscale accelerometer elements. More recently, MEMS gyroscopes (i.e., rate sensors) 6 https://www.mems-exchange.org/MEMS/applications.html 7 https://www.mems-exchange.org/MEMS/applications.html#Biotechnology 8 https://www.mems-exchange.org/MEMS/applications.html#Communications 9 https://www.mems-exchange.org/MEMS/applications.html#Inertial%20Sensing CHAPTER 1. STATE OF THE ART 22 have been developed for both automobile and consumer electronics applications. MEMS inertial sensors are now being used in every car sold as well as notable customer electronic handhelds such as Apple iPhones and the Nintendo Wii. 1.3.4 Medicine There are a wide variety of applications for MEMS in medicine 10 . The first and by far the most successful application of MEMS in medicine (at least in terms of number of devices and market size) are MEMS pressure sensors, which have been in use for several decades. The market for these pressure sensors is extremely diverse and highly fragmented, with a few high-volume markets and many lower volume ones. 1.5 Printed Circuit Board – PCB technology A Printed Circuit Board or PCB is a flat plastic or fiberglass board on which interconnected circuits and components are laminated or etched. This is an old technology that is well known and available in many countries. Chips and other electronic components are mounted on the board. Very often, computers consist of one or more printed circuit boards, usually called cards or adapters 11 and interconnected by wires and connectors. Printed Circuit Board (PCB) technology is a today very well expanded technology. It is feasible to design with open tools the whole satellite and for less than 300€ manufacturer will build and assemble your design in only few days. Other approaches like the CubeSat standrard require a structure that holds few boards and a complicated wiring system that introduces extra complexity. Each system is placed in a different board. These designs are board oriented since WikiSat approach is component oriented everything placed in a single board. The advantages of PCB technology 12 are: • Its use makes the design and implementation very accessible. • PCB manufacturing process is more simple and cheaper than silicon technology (materials and equipment). • Smaller and lighter. • Less sensitive to noise. • Increased compatibility electromagnetic. • Greater mechanical strength. • Rapid prototyping. • Can be manufactured in series. • Total integration of electronic components and fluidics on the same PCB. • Monolithic devices that manipulate, analyze and control fluids. • Applications biological, chemical, medical. 10 https://www.mems-exchange.org/MEMS/applications.html#Medicine 11 http://www.thefreedictionary.com/printed+circuit+board 12 http://iecon02.us.es/ASIGN/SEA/MEMS3_PROC3_PCBMEMS.pdf 23 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit Some alternatives for PCBs technologies 13 include wire wrap and point-to-point construction. In order to build a PCBs, initially it must be designed and laid out then it becomes cheaper, faster to make and potentially more reliable when high-volume production are taken into account; then production and soldering of PCBs can be automated. Many electronics industry of PCB design, assembly, and quality control required are set by standards that are published by the IPC organization 14 . An example of PCB used in one of the WikiSat missions (specifically at the Launch05, a mission carried out in Zaragoza 15 , July 09th, 2011, that was designed as a Tracked recovered mission with PVC launching ramp in bad weather conditions) Launch05 is seen in the Figure 3: Figure 3 – PCB used for the Launch05 and a WikiSat v4.0 prototype. Source: Joshua Tristancho 1.6 Surface Mounted Device - SMD technology Surface Mount Device (SMD) technology is another improvement in terms of weight saving, size reduction, high shock resistant and robustness compared to other technologies like through-hole used very often in the CubeSat approach. They are components soldered to a PCB board through a paste. Because they are easy to assemble during the re-flow, we are interested in the use of these devices for the femtosatellite development. Many electronic components are available in this format: High Definition Camera (HDC), Multipurpose Computer Unit (MCU), Inertial Measurement Unit (IMU), etc. The Leadless Chip Carrier (LCC) is another version compatible with SMT technology without soldering. Connections are made by any four edges. Chip carriers may have either J-shaped metal leads for connections by solder or by a socket, or may be lead-less with metal pads for connections. Also it is known as “Flat-pack” If the leads extend beyond the package. Figure 3 have two examples of this technology: an u-blox GPS 16 and a TOSHIBA camera 17 . The future WikiSat will include these two LCC components that were not included in 13 http://download.intel.com/design/chipsets/applnots/29817901.pdf 14 http://www.ipc.org/ContentPage.aspx?pageid=IPCs-Name 15 http://code.google.com/p/moon-20/wiki/WikiBalloon_ 16 http://www.u-blox.com/en/gps-modules/pvt-modules/neo-6-family.html 17 http://kreature.org/ee/avr32/tcm8230/tcm8230.jpg CHAPTER 1. STATE OF THE ART 24 the previous satellite version. This technology permits to include the client component inside the design cycle when the satellite application is to test a new MEMS system or LCC component in the nearspace. Figure 4 - LCC devices: u-blox NEO6M GPS (a) Source: u-blox and TOSHIBA TCM8230 camera (b) Source: TOSHIBA Some manufacturers assemble their Commercial-off-the-shelf (COTS) solutions in the LCC format that is compatible with SMD technology as we saw before but in such a way that it can be integrated in the PCB board of the satellite as another SMD component does. We will use this fact to propose some solutions to the communications system and overcome this challenge. 25 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit CHAPTER 2. SYSTEM REQUIREMENTS This chapter has the list of minimum requirements that are necessary for the correct operation of the antenna. The requirements are classified as: system requirements, high level requirements and low level requirements. These requirements were extracted from Lara Navarro requirements list in [11]. 2.1 System requirements There are two system requirements: • SR01 The communications system shall fit inside the femtosatellite. • SR02 The communications system shall have a mass smaller enough to fit the satellite in the category of femtosatellite. 2.2 High level requirements There are two high level requirements: • HLR01 The communications system shall transmit and receive the tracking and payload information. • HLR02 The communications system shall be simple and based on COTS. 2.3 Low level requirements There are nine low level requirement for the first high level requirement and three low level requirement for the second high level requirement: • LLR010 The communications system shall transmit the payload information to a ground station. • LLR011 The communications system shall broadcast the tracking information to any ground station or other femtosatellite. • LLR012 The communications system shall receive new commands from the control centre. • LLR013 The communications system shall be inoperative during the inactive phases of the orbit. • LLR014 The communications system shall work in a range of 500 km. • LLR015 The communications system shall have a signal-to-noise ratio of at least 3 dB. • LLR016 The communications system shall have a band-with of at least 9,600 bps. • LLR017 The communications system shall be able to illuminate an area of 200 km. CHAPTER 3. CASES OF STUDY 32 As an improvement we found that the Case 2 is enough a maximum range of 2,500 km respect to the 500 km of the nRF24L01P. Moreover, it has the advantage that is validated for its use at the space. At the Case 3, corresponding to the 9XTend, is observed that doesn’t carry out with the requirements of: 1. SR01 The communications system shall fit inside the femtosatellite. Equal that the previous case, the system of communications has a superior dimensions respect to the maximum specificity by the PCB board. 2. LLR018 The communications system shall be electrically supplied by the same voltage as the femtosatellite. In spite of works with an average voltage of 3.3 V, the voltage that is needed for to obtain the maximum power is of 5 V, thus doesn’t carry out the requirement of to feed to the same voltage that the femtosatellite. On the one hand, as occurs at the Case 2, the time of life of the battery is insufficient for realize communications, being that 1 hour we permit to realize 7 communications totally, and for this type of missions, where the satellite is in orbit about 3 days, results limited. It is possible sends it, but isn’t advisable. Cost is very high if we compare with the Case 1 and 4. On the other hand, it has as advantage that its distance of maximum range is of 3,800 km, while that the nRF24L01P is limited to 500 km. Finally, at the case of NTX2, it carries out all the minimum necessary requirements for the correct working of the radio-link. The dimensions are a bit larger but area is smaller, replacing the original WikiSat antenna of 141x34 mm by the new of 43x15 mm and the antenna that is a wire of few centimeters. Furthermore, the maximum range that reaches is bigger than the original nRF24L01P, and the same occurs with the autonomous of the battery, that is of 33.9 hours respect to the 6.6 hours of the Case 1. Nevertheless, the nRF24L01P still weight less: 20 grams in front of these 25 grams that weights the NTX2 as we will present in the next chapter. 33 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit CHAPTER 4. SPECIFICATIONS In this chapter main radio-link issues are presented. The original design of the WikiSat nRF24L01P antenna was proposed by Fernandez-Murcia in [14] but without margin. Also is presented de cost budget of the four antennas, the required energy for the four cases and, finally, it is explained the manipulation of one of them. 4.1 Link budget In order to know the communications parameters as was proposed by Fernandez-Murcia in [14], it is necessary an accurate power link budget for the communication where the minimum link distance is fixed at 500 km. The budget is initially set as a download link from the satellite to the ground station. Initially, we have proposed to use the 9XTend transceiver 34 but since the expectations are not meet, other transceivers such as the SSTV 10MW transceiver 35 or the NTX2 transceiver 36 are considered. See annexes for datasheets. We propose to start from the original WikiSat communication system based on the Nordic nRF24L01P transceiver 37 at 2.4 GHz System-on-Chip working at 250 kbps bandwidth, 0 dBm TX power and GFSK modulation. The link budget is based in the equation 4.1 where extra components like amplifiers (in both sides of the radio link) are necessary to increase the range. It is mandatory to begin with the computation of how many extra G extra gain (dB) will be necessary at a distance of 500 km. Having: rxrxtxtxtxrx eGPLFLFSeGPP −+−−−+= (4.1) Equation 4.1 can be easily transformed in order to estimate the extra gain necessary as shown in Equation 4.2. min,rxrxrxtxtxtxextra PeGPLFLFSeGPG −−+−−−+= (4.2) For the transmission, a power amplifier (PA) with an adequate trade-off of gainconsumption, easy to implement (not too much components) and the better OIP 3 and P1dB as possible are the main specifications considered. The selected power amplifier is the PA2423L from SiGe manufacturer. From point of view of reception, the noise figure and gain are critical; hence the selected component is a Low Noise Amplifier (LNA), the ADL5521 from Analog Devices, by its low noise figure, and is located as close to the antenna as possible. 34 http://www.Digi.com/pdf/ds_xtendmodule.pdf 35 http://www.Argentdata.com/files/SSTVCam.pdf 36 http://www.Radiometrix.com/files/additional/ntx2nrx2.pdf 37 http://www.Nordicsemi.com/eng/Products/2.4GHz-RF/nRF24L01 CHAPTER 4. SPECIFICATIONS 34 As a matter of summary, the figure 9 shows the schema of femtosatellite communication as well as the link budget calculations with the original WikiSat communications module [14]: Figure 9 – Femtosatellite diagram block and link budget for the original nRF24L01P configuration. Source: Enric Fernandez This compute is achieved for a separation of 500 km. Due to the different polarization of the antennas (one linear and the other circular), a polarization loss factor (PLF) of 3 dB has been considered. This is critical because the polarization may change the satellite movement or produce any other undesired effect. A circular polarization (20 dB of gain) Yagi antenna is selected for reception and is considered a 6 dB antenna (the gain expected for the array) for transmission. Finally, 0.5 dB losses due efficiencies have been considered at each side of the link. Also we have considered the same values for the tx G antenna and ground segment. All these values are fixed factors that not change at the schema and the design of system communication. For the precise case of nRF24L01P, the operating frequency (f 0 ) selected is 2.4 GHz. Note that for the Loss in Free Space (LFS) or FSPL (Free Space Path Lost) is not the same for all the cases because it depends on the frequency that each implementation requires. For the others losses are taken the same values as Case 1 from the original schema of WikiSat. From equation 4.2, we proceed to compute the extra gain for every implementation that we propose: the 10MW implementation, the WikiSat v4.1 implementation, the 9XTend implementation and the NTX2 implementation, beginning with the original design nRF24L01P: CASE 1. nRF24L01P The original nRF24L01P implementation has dBmP tx 18= , dBLFS GHz 35.154 4.2 = , the extra G is computed in equation (4.3). dBmPeGPLFLFSeGP rxrxrxtxtxtx 0 min, =−−+−−−+ (4.3) In this case, there is no extra gain, so the maximum range is kmd dBGtx 500 0 = = . 35 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit CASE 2. 10MW The FPV 10MW implementation for the Argent SSTV camera has dBmP tx 5.39= , dBLFS GHz 06.64 8.5 = , Figure 10 – Femtosatellite diagram block and link budget for the 10MW configuration. Adapted from: Enric Fernandez In the second case, the extra G is computed in equation (4.4). dBPeGPLFLFSeGP rxrxrxtxtxtx 79.111 min, =−−+−−−+ (4.4) This extra gain allow us to achieve a maximum range of kmd dBGtx 500,2 0 = = . CASE 3. 9XTend The Digi 9XTend implementation has dBmP tx 27= , dBLFS MHz 98.55 902 = , Figure 11 – Femtosatellite diagram block and link budget for the 9XTend configuration. Adapted from: Enric Fernandez In the third case, the extra G is computed in equation (4.5). dBPeGPLFLFSeGP rxrxrxtxtxtx 37.107 min, =−−+−−−+ (4.5) This extra gain allow us to achieve a maximum range of kmd dBGtx 800,3 0 = = . CASE 4. NTX2 The Radiometrix NTX2 implementation has dBmP tx 14= , dBLFS MHz 80.52 434 = , 10MW 9XTend CHAPTER 4. SPECIFICATIONS 36 Figure 12 – Femtosatellite diagram block and link budget for the NTX2 configuration. Adapted from: Enric Fernandez In the last case, the extra G is computed in equation (4.6): dBPeGPLFLFSeGP rxrxrxtxtxtx 55.97 min, =−−+−−−+ (4.6) This extra gain allow us to achieve a maximum range of kmd dBGtx 800,1 0 = = . The km LFS 500 is obtained using the next equation (4.7): 2 4      =c fd LFS π (4.7) Where, supposing that maximum range is kmd 500 = , knowing that speed of light in a vacuum is smc /103 8 ×= , and setting the frequency of each case, we obtain the different values of LFS . Once we have calculated the value of the extra gain for each case, for to obtain the value of the maximum ranges, we have used the equation (4.8): kmRange f LFS 3log 20 5.147 max 10 −− − = (4.8) Where, if it is added the value of km LFS 500 with the value of the extra G calculated, is obtained the value of the max LFS . This is the maximum value of LFS that each case can reach and that is obtained when the femtosatellite arrives to the maximum range, in which the extra gain will be dBGG txextra 0== . 4.2 Energy budget The electrical power source is a battery, not a solar panel and the power budget has an important limitation. The satellite will have a distributed voltage regulation strategy, figure 13(a), because it has a single source, the battery and each SMD component will have a voltage regulator inside. Instead, the payload will have a centralized strategy, figure 13(b), because each voltage level is NTX2 37 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit supplied from a single voltage regulator, feeding to any payload SMD component in the payload area. Figure 13 – Voltage regulation diagram blocks: distributed strategy (a) and centralized strategy (b). The diagram block for a distributed strategy in figure 13(a) shows how this schema achieves the best battery usage while the centralized strategy in figure 13(b) has a weak point that is the regulator. 4.2.1 Power budget For the power budget, there are two working modes: Standby and Active. The active mode is the most consuming state that the satellite has when downlink is established and satellite is pointing towards the required station through the Magnetorquers. These magnetorquers can generate a magnetic field in order to have an attitude control to point the high gain antenna towards the ground station or to follow an interesting point for the payload. The available power should be used only when necessary. Navarro in [11] has calculated the total time of the mission when the satellite could stays in active mode. During a total of nine days of mission, there are about 382 minutes of a total of about 13,000 minutes of downlink. Only 3 percent of the mission time, the femtosatellite will have an important battery leak. The total mission consumption is about 520 mAh and the total available is 610 mAh. The average consumption per hour is 2.4 mA/h. Each case is studied following and they were summarized in table 2. CASE 1. For the case of the nRF24L01P, the power consumption is 92 mA. The battery can afford a peak of power is 12 A. The maximum continuous operation of this module is 6 hours, 37 minutes and 48 seconds. CASE 2. For the case of the 10MW, the power consumption is 4.5 A. The original battery can afford a peak of power is 12 A. The maximum continuous operation of this module is 8 minutes and 8 seconds. Obviously, a battery pack is required in this case. CASE 3. For the case of the 9Xtend module, the power consumption is 600 mA. The battery can afford a peak of power is 12 A. The maximum continuous operation of this module is 1 hour and 1 minute. CASE 4. For the case of NTX2 module, the power consumption is 18 mA. The battery should feed this power is 12 A. The maximum continuous operation of this module is 33 hours, 53 minutes and 24 seconds. CHAPTER 4. SPECIFICATIONS 38 4.2.2 Power source For this kind of missions, due to the short mission time, it is strongly recommended to use batteries instead of solar panels. As reported by Navarro in [11], the 34 percent of the mass budget is for the battery that represents 6.6 grams compared to the tracking subsystem that is the 36 percent of the mass budget in 7.0 grams. In the early designs, i.e. WikiSat v3 a coin battery was selected having a better consumption to mass ration that the current LiPoly batteries. The main problem that a coin battery has got is not the fact that it is no rechargeable but it has a very low drain power, about 50 mAh, while the total consumption is 610 mAh. LiPoly batteries have maximum power in the order of 12 Ah for a short time. Different values for each case are summarized in table 2: Table 2 – Link-budget summary (Four cases) Freq. P tx LFS G extra Range Power Live CASE 1.nRF24L01P 2.4 GHz 18.0 dBm 154.35 dB 0.00 dB 500 km 92 mA 6:37:48 CASE 2. 10MW 5.8 GHz 39.5 dBm 64.06 dB 111.79 dB 2,500 km 4,500 mA 0:08:08 CASE 3. 9XTend 902 MHz 27.0 dBm 55.98 dB 107.37 dB 3,800 km 600 mA 1:01:00 CASE 4. NTX2 434 MHz 14.0 dBm 52.80 dB 97.55 dB 1,800 km 18 mA 33:53:14 In table 2, transmit power has been converted 38 in dBm units using the following equation (4.9) where 1 watt is 30 dBm. ( ) ( ) 30log101000log10 )(10)(10)( +⋅=⋅⋅= WWdBm PPP (4.9) As well as the power consumption or continuous live time, marked in red the parameters that do not fit any requirement. Available power is 610 mA from the main battery and the minimum operational live time is set at a minimum of 6 hours of continuous recording as calculated Navarro in [11]. It is observed the required values of each case (recover of their respective datasheets), as well as: frequency, power tx P , the LFS and the required power. On the other hand, if is fixed the maximum distance at 500 km (bringing with reference always the nRF24L01P, whose distance of maximum range is 500 km), is obtained the extra gain extra G that is seen at the table 2. It should be noted that the nRF24L01P has an extra gain of 0 dB, being that cannot reach a major distance. At the range we observe the maximum real distances to which arrives each one of the implementations. For these distances, the dBG extra 0= . Also it is shown the useful life for a continued use, and coming determinates for the calculations shown on the 4.2.1 section based of the power that requires each case. Typical extra gain in communications is dBG Typical 6= but some amateur satellites are even more. Requirement LLR015 stated this margin at dBG Typical 3= . The original nRF24L01P communication system was designed 38 http://www.rapidtables.com/convert/power/Watt_to_dBm.htm 39 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit with no margin which means that in practice, the range is in fact less than 500 km. The proposed cases have extra margin instead, which means that the range will be more than 500 km as showed in table 2. 4.3 Bill of materials Table 3 presents the bill of materials of the original nRF24L01P implementation and the new components such as the transceivers and power amplifiers for each option or implementation presented in the chapter 3. Table 3 – Mass and cost budget (Four cases) Provider Model Case Size mm Cost MCU computer Atmel ATmega1682 1,2,3,4 4 3.07€ Accelerometer ST LIS331HH 1,2,3,4 3 3.64€ Rate gyroscope Invensense ITG-3200 1,2,3,4 4 25.39€ HD Camera TOSHIBA TCM8239MD 1,3,4 6 9.95€ SSTV Camera Argent SSTVCA 2 36 60.00€ Serializer TI SN74HC165PW 1,3,4 4 0.27€ IO expander TI TCA6408A 1,2,3,4 4 1.86€ Voltage regulator TI TPS719XXXX 1,2,3,4 3 1.36€ Transceiver 2.4 GHz Nordic nRF24L01P 1 4 3.78€ 5.8 GHz FPV 10MW 2 158 21.75€ 902 MHz Digi 9XTend OEM RF 3 61 141.52€ 434 MHz Radiometrix NTX2 4 43 19.38€ Power Amplifier 2.4 GHz SiGe PA 2423L 1 3 2.63€ 5.8 GHz KU PA 5359 2 158 600.00€ 902 MHz Digi Internal 3 61 - 434 MHz Radiometrix Internal 4 43 - In the table 3 we can see the cost budget for each case, furthermore of the size, provider and model of each material. For the transceiver, the cheapest is the nRF24L01P implementation, and the next cheaper is the NTX2. For its part, the most expensive is the 9XTend implementation. If we notice at the power amplifier, it is repeated that the cheapest is the nRF24L01P implementation. In this case, we have not information about the cost of Digi and Radiometrix power amplifier, but the cost of 10MW implementation is known. 4.4 Digi 9Xtend test There is experimental information about all the implementations in nearspace except for the Digi 9XTend. For this reason I proceeded to make a test with the 9XTend module which consisted of to realize a realistic radio-link between two 9XTend modules. The reason of choose it, is determined by that we have of CHAPTER 4. SPECIFICATIONS 40 two modules for realize the transmission and reception of data. Nevertheless, at the beginning we haven’t got the necessary components to create the radio-link: the antenna of the transmitter module, and the FTDI converter from UART for the receptor module to USB for the PC (That emulates the ground station). So, is explained the manufacturing, certification and validation of the antenna and, finally, the test of radio-link. 4.4.1 Antenna manufacturing We tried to find a 902 MHz antenna with a Reverse Polarity SubMiniature version A (RPSMA) connector but it was not possible in our location. The alternative option was to manufacture our own lambda/4 monopole antenna from a SMA adapter and a wire. See figure 14. The working frequency is around 902 MHz so the wire length is computed by the equation (4.10) in mml MHz 2.83 902 = . mm f c l MHz 2.83 109024 103 4 6 8 902 = ⋅⋅ ⋅ == (4.10) Figure 14 shows the process. The nut (1) and the Rubber (2) are assembled with the needle (3) and the wire, removing the varnish layer (4) with a light before solder (5). The female needle should not be filled with tin to do not damage the radio male needle connector. The rubber is placed (6) and sealed with extra wire length (7). The nut is a SMA plug connector, the needle inside, see last annex. Figure 14 – 902 MHz lambda/4 antenna manufacturing 4.4.2 Monopole antenna certification (902 MHz SMA) The monopole antenna certification process as prototype consists of the antenna calibration and the antenna validation. This antenna is manufactured by me with the collaboration of the WikiSat team. This is the manufacturing procedure for a 902 MHz antenna, 9 dB gain with a Reverse Polarity SubMiniature version A (RPSMA) connector. It is based on a lambda/4 monopole antenna extracted from a SMA adapter and a wire. The working frequency is around 902 MHz so the wire length is computed by the equation (4.10) in mml MHz 2.83 902 =. The antenna prototype certification process is done using an Agilent CSA Spectrum Analyzer model N1996A where the “Stimulus response – Return Loss” mode is selected. For the calibration procedure, first of all, a large range is selected from 400 MHz to 1 GHz as showed in figure 15. A calibration process is done as explained by Ángel de las Heras in [17] in section 4.4.1 41 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit Equipment calibration (Page 74). The wire is cut slowly until the best response for the working frequency selected with the marker at 901.176 MHz is obtained. Figure 15 – Antenna A. Best frequency 905.882 MHz with -9.7 dB and SWR 1.97 Figure 16 – Antenna B. Best frequency 904.329 MHz with -9.5 dB and SWR 2.01. Worst frequency 922.91 MHz with -9.0 dB and SWR 2.11 CHAPTER 6. BIBLIOGRAPHY 48 [11] Doerksen, K., et al., Design, modeling and evaluation of a 2.4ghz fhss communications system for narcissat. 17th AIAA/USU Conference on Small Satellites, Stanford, CA, USA, 2003 http://Digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1790&context=small sat [12] Hamroun, C., Design and prototype of a flight microstrip antennas for pico satellite erpsat-1, 4ht International Conference, Istanbul, 2009 http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5158292&tag=1 [13] Hall, C. D., Virginia tech ionospheric scintillation measurement mission, 13th Annual AIAA/USU Conference on Small Satellites, 1999 http://Digitalcommons.usu.edu/cgi/viewcontent.cgi?article=2133&context=small sat [14] Fernandez-Murcia. E., et al., A synthetic aperture antenna for femtosatellites based on commercial-of-the-shelf. 29th Digital Avionics Systems Conference. Seattle, 2011 http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber=6096138 [15] Bardolet. E., Study of a low cost inertial platform for a femtosatellite deployed by a mini-launcher, UPCommons, vol., no., pp., 2010 http://upcommons.upc.edu/pfc/bitstream/2099.1/9668/7/TFC_EsteveBardolet_ memoria_V2.pdf [16] Tristancho, J., Implementation of a femtosatellite and a minilauncher. Master’s thesis, UPCommons, vol., no., pp., 2010 http://upcommons.upc.edu/pfc/bitstream/2099.1/9652/1/memoria.pdf [17] De las Heras, A., Design and implementation of a synthetic aperture antenna for a femto-satellite, UPCommons, 2011 http://upcommons.upc.edu/pfc/bitstream/2099.1/11686/1/memoria.pdf 49 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit WEB REFERENCES [6.1] http://www.Argentdata.com/files/SSTVCam.pdf (May 2013) [6.2] http://www.fpvhobby.com/transmitter/21-2-55-volt-500mw-24ghz-videotransmitter.html (May 2013) [6.3] http://www.kuhne-electronic.de/en/products/power-amplifiers/ku-pa5359-a.html (March 2013) [6.4] http://www.Nordicsemi.com/eng/Products/2.4GHz-RF/nRF24L01 (Juny 2013) [6.5] http://www.datasheetcatalog.org/datasheet/SiGe/PA2423L-EV.pdf (Juny 2013) [6.6] https://www.sparkfun.com/products/9411 (Juny 2013) [6.7] http://www.Radiometrix.com/files/additional/ntx2nrx2.pdf (Juny 2013) ANEXES TÍTOL DEL TFC: Implementació d’un radio-enllaç de llarg abast per a femto-satèl·lits en òrbita molt baixa TITULACIÓ: Enginyeria Tècnica Aeronàutica, especialitat Aeronavegació AUTOR: Sara Izquierdo Jiménez DIRECTOR: Joshua Tristancho Martínez DATA: 29 de Octubre de 2013 53 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit DATASHEETS Manufacturer Model Source 6.1 Argentdata SSTV http://www.Argentdata.com/files/SSTVCam.pdf 6.2 FPV 10mW http://www.fpvhobby.com/transmitter/21-2-55-volt-500mw-24ghz-video-transmitter.html 6.3 Kunhe PA5359 http://www.kuhne-electronic.de/en/products/power-amplifiers/ku-pa-5359-a.html 6.4 NORDIC nRF24L01 http://www.Nordicsemi.com/eng/Products/2.4GHz-RF/nRF24L01 6.5 SiGe PA2423L http://www.datasheetcatalog.org/datasheet/SiGe/PA2423L-EV.pdf 6.6 Digi 9XTend https://www.sparkfun.com/products/9411 6.7 Radiometrix NTX2 http://www.Radiometrix.com/files/additional/ntx2nrx2.pdf 6.8 SMA connector family http://i01.i.aliimg.com/photo/v0/256281235/SMA_connector.jpg ANNEXES 54 6.1 Argentdata SSTV camera datasheet http://www.Argentdata.com/files/SSTVCam.pdf 55 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit ANNEXES 56 6.2 FPV 10 mW AV transmitter datasheet Provider: FPV Model: 10MW Source: http://www.fpvhobby.com/transmitter/21-2-55-volt-500mw-24ghz-videotransmitter.html Type: Transmitter module TX power: 10 mW Frequency: 5.8 GHz Range: 100 meters Data: Audio and Video Current: 70 mA Voltage: 3.3 V Size: 20x20x4 mm Weight: 1.2 grams Cost: $20.00 Channels: Ch1:5705mhz , Ch2:5685mhz , Ch3:5665mhz , Ch4:5645mhz , Ch5:5885mhz , Ch6:5905 , Ch7:5925mhz , Ch8:5945mhz 57 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit 6.3 Kuhne PA5359A power amplifier datasheet http://www.kuhne-electronic.de/en/products/power-amplifiers/ku-pa-5359-a.html ANNEXES 64 65 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit ANNEXES 66 67 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit ANNEXES 68 69 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit ANNEXES 70 71 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit ANNEXES 72 73 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit ANNEXES 80 81 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit 6.6 Digi 9Xtend RF module datasheet https://www.sparkfun.com/products/9411 ANNEXES 82 83 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit 6.7 Radiometrix NTX2 transceiver datasheet http://www.Radiometrix.com/files/additional/ntx2nrx2.pdf ANNEXES 84 85 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit ANNEXES 86 87 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit ANNEXES 88 89 Implementation of a long range radio-link system for femtosatellites in very Low Earth Orbit