Figure 1. Meeting at SpaceQuest, February 8, 2002. This photograph was taken during a joint meeting of the project team and the AMSAT-NA executive committee with SpaceQuest on February 8, 2002. Shown, clockwise from the left, are Linda Jacobsen (SpaceQuest), Art Feller W4ART (AMSAT-NA Treasurer), Rick Hambly W2GPS and Dick Daniels W4PUJ (AMSAT OSCAR E project team), Dino Lorenzini KC4YMG (SpaceQuest), Robin Haighton VE3FRH (AMSAT-NA Presi- dent), and Keith Baker KB1SF (AMSAT-NA Executive Vice President). In attendance but not shown is Mark Kanawati N4TPY (SpaceQuest). AMSAT OSCAR-E A New LEO Satellite from AMSAT-NA Rick Hambly, W2GPS ([email protected])

This was last done for AMSAT are available for one or more optional AMSAT-NA has embarked on the con- OSCAR-D, which became AMSAT payloads that will be provided by struction of a new Low Earth Orbit (LEO) OSCAR-8 after launch and commission- AMSAT volunteers. satellite that will be called AMSAT ing. AMSAT didn't use letters for the first OSCAR-E, or “Echo” until it achieves four Microsats and the Phase 3 series The AMSAT OSCAR-E project team is orbit and receives the next sequential started again with “A”. led by Dick Daniels, W4PUJ and includes OSCAR number. Keith Baker KB1SF Tom Clark, W3IWI and Rick Hambly, was referring to this satellite when he It has been 12 years since AMSAT-NA W2GPS. Oversight of the project team is introduced a new “MICROSAT-class built and launched the original Microsats provided by the AMSAT-NA executive project” in the Apogee View column of in 1990, and 8 years since AO-27 was committee and the Board of Directors. the March/April issue of The AMSAT launched in 1993. AMSAT OSCAR-E The core of AMSAT OSCAR-E will be Journal. will put AMSAT-NA back in the satellite built by SpaceQuest, Ltd. a company that business while providing an improved is owned and staffed largely by AMSAT- Notice that with this satellite AMSAT is companion for AO-27, which has been NA members including Mark Kanawati, returning to the practice of designating very popular with hams for the past 8 N4TPY and Dino Lorenzini, KC4YMG. LEO satellites by sequential characters. years, but is getting old. Space and power AMSAT OSCAR-E W2GPS original Microsats, as shown by the full size model in the background. These original Microsats were AO-16, DO-17, WO-18, and LO-19. They were followed by the descendents of that legacy, includ- ing IO-26, AO-27, MO-30, and SO-41.

Internally the spacecraft consists of a vari- ous electronic subsystems including: · 4 VHF receivers, · 2 UHF transmitters, · 6 modems, · Flight computer, · RAM disk, · Batteries, · Battery charger and voltage regulators, · Wiring harness, · RF cabling, · RF switching and phasing net- works, · 56 channels of telemetry, and Figure 2. A mockup of AMSAT OSCAR E in front of an original AMSAT Microsat · Magnetic attitude control.

· Spacecraft flight software Figure 3 shows a conceptual block dia- The remainder of this article will be di- · Power generation and distribu- gram of the AMSAT OSCAR-E space- vided between an overview of the core tion craft. The items enclosed in dashed lines satellite systems and descriptions of can- · Command and control – ground are not a part of the basic AMSAT didate optional payloads. (The informa- station and satellite OSCAR-E mission, but are under consid- tion in this article borrows heavily from · A basic set of receivers, transmit- eration as secondary payloads. “Microsat Mission Study Report” by ters and antennas Mark Kanawati, N4TPY, commissioned · Space for optional payloads by AMSAT-NA and submitted by Physical structure SpaceQuest, Ltd. to AMSAT-NA on The satellite with just this set of subsys- January 9, 2002.) AMSAT OSCAR-E’s overall structure tems will have an impressive array of consists of a stack of five machined alu- functions including FM voice operation minum modules. Each module measures AMSAT OSCAR-E: Core Subsystems (EasySat), 9600 bps data channel(s), and a approximately 9.5 inches x 9.5 inches. multi-band receive capability. The height of each module is adjustable In the decade since AMSAT-NA built the up to a total of 9.5 inches. The nominal Microsats, SpaceQuest has made many AMSAT OSCAR-E is a Microsat class useful internal area is approximately 8 improvements to the Microsat concept. spacecraft weighing approximately 10 kg. inches x 7.5 inches. Each module houses AMSAT OSCAR-E’s core subsystems The spacecraft consists of five solid alu- a different spacecraft subsystem. closely resemble those of the original Mi- minum trays, each with four walls and a crosats but show the benefit of years of bottom stacked to form approximately a Modules are interconnected by RF cables development and technology advance- 10-inch cube structure. A top cover is and a wiring harness carrying power, in- ments. provided for the top tray. Six solar panels ter-module data, telemetry, and control attach to each of the six sides for power signals. Four machined rods running the The subsystems that make up the core generation. Additionally, several anten- height of the spacecraft are used to bolt elements of AMSAT OSCAR-E are: nas protrude from the top and bottom sur- the assembly together. Figure 4 shows a faces. Figure 2 is an example of what the photo of a typical Microsat structure. · The physical structure AMSAT OSCAR-E structure might look · Attitude control like, although the antennas will be quite · Central processor hardware different. Note the similarity to AMSAT’s

2 May/June 2002 AMSAT OSCAR-E W2GPS AMSAT OSCAR-E employs a passive thermal control system and has no on- Multi-Band VHF Antenna Antenna board propulsion. Almost all of the satel- 28 MHz – Low Frequency lite’s surface area is covered by solar 1.3 GHz Antenna 100 KHz-30 MHz cells. Some surface area is required for antenna mounts and launch vehicle inter- Band Front-- Switch VLF Filter PreAmp End faces. The remaining surface area is cov- Experiment FilterFilter ered with thermal absorbing and reflective tape to balance the spacecraft’s thermal behavior. Switch 4 Way Power Divider A separation mechanism needs to be de- signed to adapt the satellite to a particular Multi-Band Receiver RX- VHF VHF VHF VHF launch vehicle. Finalizing the separation 4 PSK31 RX-1 RX-2 RX-3 RX-4 mechanism will await selection of a launcher although one version already Control exists for the Russian Dnepr launcher due to SpaceQuest's previous use of that Audio or Audio or Audio or Audio or launch vehicle. Dnepr is a de-militarized 600 bps – 115 Kbps 600 bps – 9600 bps 9600 bps 9600 bps Flight Data Processor Russian ICBM. 15 MHz V-53A CPU – 16MB RAMDISK – 6 GMSK Modems

A standard commercial shipping container will be used to transport the AMSAT

Other Digital UHF UHF OSCAR-E to the launch site. EX-1 EX-1 Op tional Voice Payload Recorder Attitude control UHF UHF HPA-1 HPA-1 The basic AMSAT OSCAR-E passive TX 1 TX 2 attitude control system consists of two permanent magnets that align the satel- 1 2 lite’s vertical axis with the Earth’s mag- Phasing Network netic field, four hysteresis damping rods L Band S RXRx W 0º 90º 180º 270º that control the satellite spin rate, and II reflective/absorptive tape that cause the T Left Hand S Band C Circular UHF satellite to rotate about its Z-axis as a re- TXTx H Antennas sult of solar photon pressure. This simple, no-power technique has been demon- strated to work well on several previous Figure 3. Conceptual Block Diagram of the AMSAT OSCAR-E Spacecraft Microsat missions. The solar-induced spin averages out the thermal load on the satellite, while the permanent magnets Central processor hardware allows one end of the satellite to point generally towards the earth. AMSAT OSCAR-E includes an Inte- The processor is clocked at 29.412 MHz, grated Flight Computer including the cen- running the bus at 14.7456 MHz. This The many advantages of this simple pas- tral processor unit (CPU), random access yields three times greater processing sive attitude control system are offset by memory (RAM), RAMDISK, and mo- throughput and three times faster interrupt one significant limitation. The permanent dems. All of these functions are incorpo- response than previous missions using this magnets cause the satellite to make two rated on a single, multi-layer, both-sides- processor. rotations per orbit resulting in one face populated PC board. favoring the Northern Hemisphere and the The boot ROM uses a standard CMOS opposite face favoring the Southern The CPU is a flight-proven, low-power EPROM running a variant of the Microsat Hemisphere. The Earth-pointing direction NEC V53A processor. This processor Boot Loader (MBL). The EPROM is is on the order of ±20 degrees in the tem- first flew in 1993 on AO-27, and has divided into two sections, alternately perate zones, varying with orbital inclina- flown on a number of LEO missions mapped into memory space with each tion. since. It is based on an x86 core and runs RESET command. Thus, if a partial fail- the Spacecraft Operating System (SCOS), ure of the EPROM occurs, the satellite also flight proven on numerous space- operating system can still be booted. This craft. See Figure 5. 3 May/June 2002 AMSAT OSCAR-E W2GPS command and control of the spacecraft. Each modem is attached to a dedicated multi-protocol serial port based on the NEC 72001 SCC. Two of the modem uplink channels are fitted with firecode detectors to provide ground-commandable RESET regardless of the state of the CPU. The variable-rate modems can go as slow as 600 bit/s and as fast as 115.2 kbit/s. The uplink and downlink data rates are set independently. Two (2) of the modems are DMA-capable, the other four (4) are interrupt-driven only. Care must be exer- cised to ensure the CPU is not overloaded with interrupts during mission planning and general spacecraft operation.

Up to eight (8) open collector N-channel FETs provide power switching control (low side switching) and several bits of 3.3V CMOS-level I/O are included. A pair of SPI ports is available for command and control functions to various modules in the satellite.

Approximately 56-channels of telemetry will be gathered on board AMSAT OSCAR-E. Eight-channel telemetry boards with 10-bit analog-to-digital con- verters are located in four of AMSAT OSCAR-E’s trays. A Serial Peripheral Interface (SPI) bus links the telemetry boards to the central processor. Twenty- four telemetry channels are built into the Battery Control Regulator (BCR) board. The telemetry includes:

· All of the solar panel voltages, cur- Figure 4. Typical Microsat Structure rents and temperature, · Battery voltages, currents, tempera- ture and charge polarity; technique has been flown successfully for provided for bulk storage of data. This · BCR regulated voltages and currents; several years. memory has no hardware error correction · Temperature of the receiver, trans- mechanism, so error control must be han- mitter, central processor, and switch- The main memory system is error- dled in software. This technique has suc- ing regulators; detecting and correcting (EDAC) using cessfully been used since the Microsats · Multi-band receiver signal strength bit-wise triple mode redundancy (TMR). launched in January, 1990. indicator; and TMR allows the safe use of wide-word · The high-power amplifier output and memory, in this case 512Kx8 static RAM A 16 megabyte NAND-Flash memory is reflected power on both transmitters. (SRAM) chips. The overall EDAC mem- included for rapid re-booting of the oper- ory size is one (1) megabyte. A portion of ating system and application tasks after A dedicated SPI bus is used to channel this memory space is remapped to allow RESET. This is modeled after the suc- the telemetry from the BCR and the indi- the boot read-only memory (ROM) to cessful FLASH operating system image vidual telemetry boards to the central occupy the highest memory addresses. reload facility of IHU-2 aboard AO-40. processor. A RAMDisk consisting of 16 megabytes Six (6) GMSK modems are included. At of serial-accessible static memory are least one will be fixed-rate for primary

4 May/June 2002 AMSAT OSCAR-E W2GPS Spacecraft Flight Software

The boot loader provides the minimal set Memory Boot EPROM of functions required to verify the satellite V53A @ 29.4 MHz Six - Channelnel 1 MByteBoot EPROMTMR EDAC health and load the operating system. The DMA Interrupts FSK Modem 1 MByteDual 128K TMR ByteEDAC boot loader runs on the initial power up, and whenever a software or hardware reset occurs. Because it resides in perma- nent memory and cannot be changed after RAMRAMDISKDISK CMOS Digital I/O FPGA Logic launch, the boot loader is simple, robust 16M Byte Open- Drain NFETs and proven.

The boot loader provides the capability to: · Send acknowledge beacons FLASH · Upload new software SPI Ports · Download memory locations 4MByte16MByte – 32MByte · Peak and Poke memory and I/O · Load software from FLASH or error- detecting and correcting memory Figure 5. AMSAT OSCAR-E Central Processor Unit (EDAC), and · Execute operating system by com- trol. This software can be loaded into which allows for flexible development mand or timer FLASH from the ground after launch, and deployment of new software. The

The Spacecraft Operating System (SCOS) Flight Data Processor has been used on all of the Amateur Radio 15 MHz V-53A CPU – 16MB RAMDISK – 6 GMSK Modems Microsat projects to date. The operating system and the housekeeping task are contained in EPROM and are moved into SPI I/O RAM for execution by the boot loader. In TLM4 TLM3 TLM2 TLM1 addition to detailed telemetry reporting, the housekeeping functions include con- 3.3V 4.6V Telemetry and control trol of the power system, transmitters and 8V 8 lines 8 lines 5 lines receivers. If needed, it can also support minimal attitude control. As was the case Multiple Line 3.3V Magnetometer for the boot loader, the operating system Switched 4.6V Power 8V 8V and minimal housekeeping task are un- BCR changeable after launch. However, up- Battery Charger and Magnet Torquers 8 IR Switchable 4.6V Attitude Control Sensors dated versions of these programs can be RX 1 – 3 Voltage Regulators uploaded and executed after launch. In Electro- order to be robust and proven, this version Switchable 8V Permanent of the housekeeping is kept as small as TX AMP 1-2 XYZ T - Rods Magnet possible. The list of off-the-self programs that execute as tasks include:

Permanent Magnet 4 spin rods (might be replaced by attitude · Memory file manager (M-FILE) from control experiment) Pre-Launch Separation Surrey Satellite Technology Ltd Power Switches (SSTL), · PACSAT File Transfer Level 0 Switched 3.3V (FTL-0) from SSTL, Optional · Transmitter Scheduling and Power Payload Monitoring from SpaceQuest, and · Supervisor Task Loader and Monitor- GaAs Panels 8V 4.5Ah NiCad ing from SpaceQuest. 1 – 6 13.2W The Mission Software provides complete control over all aspects of the satellite, including experiments and attitude con- Figure 6. AMSAT OSCAR-E Power, Telemetry and Attitude Control Block Diagram 5 May/June 2002 AMSAT OSCAR-E W2GPS complete set of software should include: tuning of default parameters. The BCR The Housekeeping Command and Control will safely manage battery charge during program communicates with each of the · Multitasking Spacecraft Operating the critical period after separation and tasks onboard the satellite. It must be System (SCOS) from BekTek before ground operators establish control. customized to support each additional · Advanced Task Supervisor On-board software can then fine-tune the task. Its primary use is to configure the · TX and RX muxing and control solar panel and battery charge limit set satellite. The housekeeping command · Telemetry monitoring, storage and points for maximum performance with and control software is also currently reporting minimum attention. DOS based. · RAMDISK management and PACSAT protocol Six GaAs Solar Panels, which are The Telemetry Gathering and Reporting · Scheduling for regional satellite ac- mounted on all six sides of AMSAT program is a standalone Windows appli- cess OSCAR-E, produce a bus voltage of ap- cation that will need to be developed for proximately 16 volts. The cells have not downloading and displaying satellite · Magnet torquer and IR attitude con- been selected yet but the minimum effi- health information. This application trol ciency will be 19% and cells with effi- would monitor a serial port, listening to · Optional experiment control ciencies up to 28% are available. The the telemetry downlink and whole earth · Addition experimental tasks, such as choice depends on their price and avail- data files. the digital recorder ability at the time the solar panel decision is made. A basic set of receivers, transmitters and Power generation and distribution antennas. The battery configuration is six NiCd The AMSAT OSCAR-E Power Subsys- cells at 4.4 Ah each with a nominal bat- The VHF antenna consists of a very thin tem consists of a Battery Control Regula- tery voltage of 8 V dc depending on tem- quarter-wave (18-inch) vertical whip tor (BCR), GaAs solar panels, matched perature and charge state. These matched mounted in the center of the top surface of flight cells, voltage regulators and a batteries have been flown successfully on the spacecraft. This piano-wire antenna power activation switch. A block diagram previous Microsat missions and are well- connects to the spacecraft with a standard of the power subsystem is shown in Figure characterized on orbit. SMA connector, and has been flown on 6. several previous Microsat missions. The BCR provides multiple switched 8-V The Battery Control Regulator (BCR) lines for both transmitters and other high The antenna feeds the low insertion loss provides a power control system designed power applications. There are also 3.3-V bandpass filter prior to entering the by SpaceQuest for small satellites. Its and 4.6-V switching regulators, capable of GsAsFET Low Noise Amplifier with a function is to convert solar panel power to over 250 mA output each, with multiple noise figure of less than 1 dB and a gain system power, and manage battery charge switched and unswitched outputs. of 18 dB. Additional filtering is accom- and protection. The BCR takes power plished by a second bandpass filter. A from solar panels with necessary restraint Separation-switch circuitry is included on four-way power divider channels the in- so as not to draw too much current and the BCR to turn all systems off while the coming signal into four VHF receivers lose panel efficiency. The main converter satellite is mounted on the rocket. An on the BCR uses this solar panel power to external connection port is provided with Four miniature VHF FM SpaceQuest re- charge the system battery, with similar two levels of separation switch override to ceivers are used for both command & restraint so as not to overcharge the bat- safely charge satellite batteries and test control and for user links. Each receiver tery. The battery charge system sets the satellite while it is mounted on the consumes less than 40 mW and weighs maximum charge voltage according to rocket. less than 50 gm. Typical sensitivity is – cell temperature, to maximize charge 122 dBm. The receiver’s IF bandwidth storage while avoiding overcharge and Command and control – ground station can be configured prior to flight at either cell heating. The charge regulator is also and satellite 15 kHz or 30 kHz, based on data rate re- prevented from reducing solar panel volt- quirements. They are capable of passing age below a preset voltage, to maximize The Bootloader Command and Control either analog or digital data up to 14.4 panel output power. The maximum bat- application communicates with AMSAT kbit/s. All of the receivers are fed directly tery charge voltage set point and the OSCAR-E’s bootloader to allow the user into GMSK modems on board the Flight minimum solar panel voltage set point can to upload necessary code changes, or to Data Processor. These receivers have be adjusted by external computer control. load and execute the operating system and flown successfully on several low-earth The battery charge regulator is a switch- tasks. This program will need to be re- orbiting spacecraft. ing design with a measured efficiency of written for AMSAT OSCAR-E. The cur- 89 percent. rent version of this software runs under AMSAT OSCAR-E has two SpaceQuest DOS. UHF FM transmitters that have been The BCR is designed to operate autono- flown on several previous Microsat mis- mously, with CPU supervision for fine- 6 May/June 2002 AMSAT OSCAR-E W2GPS sions. Each transmitter contains a PLL- KA9Q and others for applying digital 6. Low Frequency Receiver: This ex- based exciter and a Motorola high-power encoding techniques to improve commu- periment, proposed by AMRAD, uses the amplifier. The unique characteristics of nication links and bandwidth utilization. LF capability of the on-board multi-band this design include its small size, low This system would use a wide-band receiver to study LF propagation phe- mass, high efficiency, on orbit adjustable TDMA single frequency data link to sup- nomenon from the unique observation output power from 1 to 12 watts and its port multiple simultaneous users and point above the ionosphere, particularly at nominal operation is at 7.5 volts. Analog modes (voice, data, video, telemetry, etc.). 136 kHz. or digital data rates up to 56 kbit/s and The downlink will be S-band, due to the beyond are possible. bandwidth requirements. The uplink will The receiver and antenna whip are already be L-band if the single frequency TDMA on the spacecraft but a new E-field an- The overall gain of the UHF power ampli- wide-band uplink is implemented. tenna interface amplifier and antenna fier is 39 dB, generating up to 12 watts of switching hardware will need to be de- RF output with a single carrier at more 2. L-Band/S-Band Communications Sys- signed if this project is to be supported. than 60% efficiency excluding the 2mW tem: This payload, proposed by KA0ESA exciter. Both transmitters can be operated of AMRAD, describes a capability similar 7. APRS: This payload will provide a at the same time into a single antenna to that required to support the ADCARS generic APRS digipeater to support and system. High power on the UHF experiment. encourage mobile and handheld satellite downlink is needed to offset the extra path digital communications. The target loss at UHF frequencies balancing the 3. GPS Receiver: This payload was pro- ground system assumes a user with a VHF uplink. High downlink power will posed by W3IWI and W2GPS. Unfortu- 9600-baud integrated TNC/Radio with an also permit transmissions at higher data nately the NASA PiVoT GPS receiver omni antenna, either an HT or a mobile. rates and/or enable true hand-held voice that we had hoped to carry will not be The spacecraft simply digipeats all UI or data operation. The high efficiency available. If a receiver of the right size packets addressed via the paths of reduces the heat generated and absorbed and low power requirement can be found, APRSAT, RELAY or WIDE. The space- in the spacecraft and increases the useful this payload will be re-considered. craft digipeater does call sign substitution life of the transmitter. The measured out- like all APRS digipeaters and substitutes put of the UHF high power amplifier at 40 4. Active Magnetic Attitude Control: This its own call after it digipeats the packet. °C is shown in Figure 7. experiment has the potential for signifi- cantly improving the stabilization of the While it is not optimal for portable and AMSAT OSCAR-E has a UHF Turnstile spacecraft. Several possible attitude con- mobile users, incorporating an APRS ca- Antenna that is fed by SpaceQuest’s hy- trol system (ACS) configurations will be pability in the spacecraft can be done brid antenna phasing network consisting investigated. The simplest ACS concept is within the spacecraft basic bus, requiring of a strip line circuit that provides the to replace the permanent magnets with no additional hardware if 9600 FSK is appropriate quadrature phase and ampli- semi-permanent electromagnets. While used with VHF uplink and UHF tude to each of four output antenna ports physically passive, electronics are re- downlink. The downlink will have to with less than 0.5 dB of insertion loss. quired to polarize and condition the mag- share bandwidth with spacecraft telemetry netic rods. Another more involved ACS and other data downlinks. Some switch- AMSAT OSCAR-E: Candidates for concept is to use three miniature torque ing capability in one of the receivers may Optional Payloads rods for attitude control and a magne- be required. tometer for attitude determination. The following are brief abstracts describ- The implementation of APRS that is be- ing the optional payloads under considera- 5. Audio Recorder Experiment ing considered would also allow for a tion for the AMSAT OSCAR-E mission. store-and-forward mode, where copies of Other outstanding proposals have been This experiment, proposed by KK7P, will APRS packets are saved until the satellite suggested but were rejected in the first cut provide the capability for recording and is in range of a known APRS Internet by the project team for a variety of factors playing back any audio channel. It is par- Gateway station, when the APRS data can including feasibility, value to the Ham ticularly useful in recording data from the be downloaded at high speed on an en- community, cost, power budget and risk. Multi-band receiver to support the low coded data link for high reliability. It is almost certain that more cuts will frequency experiment. have to be made because it is not possible 8. PSK-31: Proposed by WB4APR, to support all the remaining payloads on a The ADCARS experiment team has rec- transponding using the PSK-31 technique single satellite the size of AMSAT ognized that, with minimal changes, the can be accomplished using the communi- OSCAR-E. hardware for the Audio Recorder Experi- cations capability of the basic spacecraft ment could also serve the ADCARS needs bus. Uplink would utilize 10 meter SSB 1. Advanced Data Communications for for computing resources. reception through the multi-band receiver. the Amateur Radio Service (ADCARS): Downlink would be via one of the UHF This payload supports the proposal by transmitters.

7 May/June 2002 AMSAT OSCAR-E W2GPS 9. Multi-band Receiver/Antenna: Pro- features from the basic satellite, even be- · Upgraded, highly capable, soft- posed by SpaceQuest, this receiver has fore optional payloads are added. These ware package. already been tested in space and can pro- include: · Store and forward with continu- vide a receive capability over a wide ous monitoring and geographi- range of frequencies from LF through L- · Analog operation including FM cally defined data forwarding. band. The development of the antenna is voice. challenging and it is currently unclear if · Digital operation including high These are only partial lists of new and the broadband antenna would be opti- speed APRS. improved capabilities. Notice that there mized for LF/HF (through 30 MHz) or for · Higher downlink power. are some tantalizing items in these lists VHF/UHF (10 meters through UHF) or · Multiple channels using two that have not been explained in this arti- both. A separate antenna will be provided transmitters. cle. They will be explored in future arti- for L-band. · Can be configured for simulta- cles. AMSAT OSCAR-E is expected to be neous voice and data, a very popular satellite. 10. High Efficiency Solar Arrays: In- · Has a new multi-band, multi- cluded in the SpaceQuest proposal to mode receiver. AMSAT, the additional power that would · Can be configured with be made available for the experiments geographically based would clearly benefit the experiments. · Haspersonalities. a true circular UHF antenna Efficiencies of up to 28% might be that maintains its circularity over achieved using a combination of flexible a wide range of squint angles. cells with a new mounting and substrate design invented by SpaceQuest. For those with an interest in the technical infrastructure of the satellite there are 11. Robust Telemetry Link: This experi- significant improvements in AMSAT ment would demonstrate the value of us- OSCAR-E: ing FEC and interleaving encoding tech- niques to improve telemetry reception by ground stations. This technique was de- · Faster and more capable IHU veloped by KA9Q and others for AO-40, processor. where it is now being considered for im- · Higher data rates on downlinks. plementation. · Autonomous, self-healing, high efficiency power management Summary system.

Power Efficiency (%) The core elements of AMSAT OSCAR-E are under construction now by 70.0 SpaceQuest. The AMSAT OSCAR-E project team is working to finalize plans 60.0 for the optional payloads.

50.0 There is the possibility that a launch op- portunity might arise before the optional payloads could be ready. If this happens 40.0 it is conceivable that the spacecraft would be launched as an EasySat only, with few, 30.0 8.0V Battery if any, optional payloads. However, it is 7.5V Battery considered likely that AMSAT OSCAR-E 20.0 will be the first in a series of new low-cost LEO satellites, each to carry optional pay- loads of interest to the AMSAT commu- 10.0 NOTE: Data collected at a heat sink nity. temperature of approximately 40C. 0.0 AMSAT OSCAR-E will be a step forward 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 in the evolution of Microsat technology, Power Output (Watts) with better receivers, higher power trans- mitters, and new operating modes. The Figure 7. UHF Amplifier RF Power Output vs. Efficiency user community will see a strong set of

8 May/June 2002