In October 2002, more than 30 experts met at AMSAT-DL in Marburg, Germany. Two projects following the successful Phase series (P3-B is AO-10 and P3-C is AO-13) got the green light, namely Phase 3-E(xpress) and P5-A. The tasks were divided and the first criteria agreed.
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Phase 3-Express
The AMSAT Phase 3-E (P3-E) satellite, also referred to as Phase 3-Express, will be intended for communication purposes of almost two million radio amateurs and scientific research. It will be built by an international team led by AMSAT-DL, together with P5-A, whose target will be Mars. The launch is planned for the period of 2004 to 2006, probably again by the Ariane space shuttle.
I will come back to P5-A. Thanks to the experience gained from previous projects and the great support of German radio amateurs, AMSAT will try to create a satellite for research on Mars. From its orbit, it should provide us with information about the surface and atmosphere of this planet. In addition, the P5A will carry a secondary payload that it will drop to the surface (probably additional probes). It is expected to be launched between 2007 and 2009. Interplanetary communication still sounds like science fiction, but it is already clear that it will be among the most important. Radio amateurs thus have a unique opportunity to actively contribute to Mars research.
But let's go back to Phase 3-Express. What will he offer us?
Even before this meeting there was a three-day meeting hosted by Dr. Karl Meinzer and DJ4ZC. Its purpose was to find a suitable control microcomputer with sufficient performance (minimum 1 million instructions per second), which would process telemetry data and instructions without problems even in difficult conditions. The 400 bit/s BPSK control used so far will be a data signal secured by Viterbi and Reed-Salomon or turbo codes. From this step, AMSAT promises to increase data reliability in adverse conditions (signal leaks, weak signals, etc.).
Common cable bundles will be replaced by a serial CAN bus with a transmission speed of 800 kbit/s. This bus was also used between some modules in P3-D (AO-40). Its advantage is the simplification of the electrical construction and easy replacement of modules.
Procesor StrongARM použitý v AO-4 sa bohužiaľ už nevyrába. Jeho alternatívou je ARM7. Do úvahy prichádzajú aj procesory Intersil RTX-2010RH a RTX-2000 (použitý v AO-21). K nemu sú dokonca výsledky radiačných testov. Žiaľ, tento procesor sa v roku 2003 prestáva vyrábať. Aby sa v budúcnosti AMSAT vyhol ťažkostiam s procesormi vyvíja vlastný Am1601 v puzdre FPGA, ktorý je možné otestovať v existujúcich radiačných testeroch. Vývoj ale potrvá ešte niekoľko rokov. Prvý prototyp IHU-3 bude musieť podporovať všetky tri procesory. Minimálna operačná pamäť bude 128kB. Keďže časové oneskorenie signálu medzi Zemou a Marsom je asi 40 minút, program bude uložený vo Flash pamäti. V prípade núdze bude môcť riadiaci tím program ľahko reštartovať. Osemmegabajtová pamäť bude slúžiť ukladanie obrázkov a zvukov.
In order for the P3-E project to be implemented as soon as possible, representatives of various companies were also invited to Marburg. The reason for speeding up the development is so that the acquired knowledge can be applied to the P5-A project.
Aj P3-E bude niesť na palube úspešný transpondér v S-pásme, ale aj traspondér s downlinkom v pásme 2m. Konečná vysokoeliptická dráha družice so sklonom asi 64 stupňov, čo umožní pri vzdialenosti 36 000km od Zeme pokrytie celej severnej pologule. Na dosiahnutie takejto obežnej dráhy bude opäť nutný raketový motor.
Due to the limited time, the mechanical design will be based on the design of AO-10 and AO-13. It will easily fit into the grippy SBS ring, making it possible to launch with the Ariane-5 shuttle.
Dlho diskutovanou otázkou boli samozrejme všetky transpondéri. Pre začiatok sa plánuje Downlink na 2m a 13cm, Uplink na 70 a 23cm. V úvahu prichádza aj downlink na 70cm a 10 GHz. Šírka pásma transpondérov bude asi 100 kHz. Inštalácia vysielačov na 5,6; 24 a 76 GHz bude závislá na zostatkovej nosnosti družice.
The IHU-3 development group submitted a proposal for the construction of a new RUDAK unit. The AMSAT-DL survey showed that the majority of radio amateurs would rather use PSK-31 than a packet mailbox. RUDAK P3-E will also work on the base DSP. Na družici budú umiestnené aj dve CMOS/APS kamery s rozlíšením 1024×1024 pixelov. Obrázky z nich budú priebežne posielané na Zem.
The list of tasks is so extensive that it will occupy almost all participating constructors. The work has already started, in the near future the KV group will meet to resolve the issue of transponders and the placement of antennas. You can find detailed information at: https://amsat-dl.org/p3e.
AMSAT Phase 3-express parameters
Project name: P3-E (OSCAR number will be known only after successful launch)
Completion date: end of 2004
Structure: similar to AO-10/13, star-shaped with three wings
Dimensions: diameter 130 cm, height 45 cm (without antenna and motor), 150 kg class
Perigee: 500 to 2,500 km
Apogee: approximately 36,000 km
Track: highly elliptical with an inclination of about 63 degrees
It will carry: receivers on 435 and 1260 MHz (possibly also 145 MHz; 2.4 and 5.6 GHz) and transmitters on 145 MHz and 2.4 GHz (possibly also 435 MHZ and 10.45 GHz)
Transmitter power: maximum 50W PEP
Transponder bandwidth: 100 kHz
Other systems: LEILA, probably RUDAK (digital and high-speed modes), coherent transponder 2.4 to 10.45 GHz, main beacon (5 bit/s and 200 bit/s – FEC), 2 to 3 cameras, possibly other systems
Team: international team led by AMSAT-DL