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Re: P3D IHU-1, IHU-2

At 09:41 AM 2000-10-01 -0400, John Zaruba Jr wrote:

>Hi BBers,
>I read the post with the URL to the "Inflight Entertainment Page", on the
>AMSAT-UK website (Thanks Richard). My understanding is that IHU-2 will
>transmit telemetry at 9k6 bauds.
>My question is, will IHU-1 be transmitting it's telemetry at 400 bauds PSK
>during launch and initial orbits?

Yes, after a brief delay following separation, it will transmit 400 bps PSK 
on the GB.  This is the primary telemetry format.

>After reading the "P3G to P3D" (The
>Provisional Preliminary Pre-flight Guide to P3D, by Paul Beckmann WA0RSE),
>it is my understanding that IHU-1 is the unit that actually controls the
>spacecraft (attitude, propulsion, power generation, etc.).


>Will the two
>IHU's share a beacon frequency, or will one IHU be one beacon 1, and the
>other on beacon 2?

There are three beacons:  general beacon (GB), middle beacon (MB), and 
engineering beacon (EB).
The IHU-2 "owns" the MB when the IHU-2  is powered on, though it can 
retransmit IHU-1 telemetry through it if desired.
The IHU-2 also has it's own IQ modulator which has a connection to the 
matrix and can be used for all sorts of interesting things, like 9k6 baud 
FSK telemetry, "real-time" audio etc.   It is this IQ modulator which will 
provide the IHU-2 9k6 downloads after launch.  This is independent of the 
main IHU-1 telemetry coming as 400 bps PSK on the GB or EB.

  Stacey E. Mills, W4SM    WWW:    http://www.cstone.net/~w4sm/ham1.html
   Charlottesville, VA     PGP key: http://www.cstone.net/~w4sm/key

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