[amsat-bb] P3E/P5A S -> X transponder

Michael Fletcher oh2aue at kolumbus.fi
Sat May 29 06:55:02 PDT 2010

Hi all ye Microwavers,

AMSAT-OH is working on the S/X band coherent/linear
transponder for P3E. The Coherent mode is a fully
functional testbed for the P5A ranging transponder.

Especially the linear transponder prototype has been
assembled and verified with over-the-air tests and
laboratory tests. Flight versions of the submodules
have been and are being produced at this time with
our eyes now set on integrating these together and
cabling the whole job together.

Full verification of the Coherent Mode requires a
fully functional command station AND a functional
IHU + CAN environment to interface our data ports with.
No such tests have been available yet, but all our
preliminary testing and evaluation of the Coherent
Processor have shown proper operation of the design
and circuitry (e.g. locking onto a "modulated" uplink
carrier, tracking this etc.). So far correct live
operation of the Coherent Mode is our biggest questionmark.

Our national team meets on a regular basis every 4 - 6 weeks
for testing and followups of the work of each individual.

This transponder is especially complex as you can
see from these key figures:

     * 9 different local oscillators
     * All local oscillators locked to the common 10 MHz USO
     * 21 different frequency mixers
     * 13 different intermediate frequencies
     * Linear Mode output power on 10 GHz: 3 W PEP
     * P5A Mode output power on 10 GHz:  1 mW PEP
     * 38 control lines on the CAN interfaces
     * 2 CAN interfaces, one in multiplexed mode
     * 4 dedicated direct control lines interfacing with the IHU
     * 14 analogue telemetry lines to the CAN bus
     * Coherent Mode Uplink/Downlink ratio is fixed at 30:7

Here you may find a general outline webpage, though unfortunately in
Finnish for the benefit of our OH supporters, but you might still enjoy
the photos and drawings:


Our team sincerely hopes funding will eventually be found
for P3E/P5A - this is the only thing that keeps us motivated
to continue our work. On the other hand we are clearly behind
schedule, so the delays are welcome :-) But then again, any
news of progress would boost our production rate phenomenally ;-)

73 Michael, OH2AUE

"Life is too short for Sudoku"

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