[amsat-bb] AO-7 command generator

[Larry Kayser <kayser@xxxxxxxxxxxx>]

Bob

I have already dropped off the reflector, Andy thanks for forwarding this 
email to me.

 >Is the person using a sound card or hardware?

He was using the command generator that was used in the check out of AO-7 
at the Lab.
He was trying to use a recording of the command generator into a .wav file 
on a portable PC and playing it out the sound card, I pushed him hard to 
junk that method so we could eliminate additional unknown variable things.

 >I see no reason this command sequence cannot be generated by software....

It can be with the proviso that very careful management is achieved of the 
envelope delay distortion.  If that decoder even sniffs some overlaid 
pulses it happily ignores the command.

There is another issue, there are NO modern amateur rigs that can do the 
required modulation to effectively telecommand AO-7.  Just as I had to in 
1972 for AO-6 shortly after launch, the chap doing the telecommand had to 
cobble up an exciter that was capable of doing the trick.  There is at 
least one manufacturer who makes kits that might be able to do the trick if 
the kit was given the fix treatment during assembly.  The fix is probably 
just leaving stuff out and bypassing things, not complicated, and you would 
have some bits to play with when finished hi.

Assuming the exciter and ability to send a single command is achieved you 
will want to make the software so that the command repetition rate can be 
varied from about 2 per second to about 3 in 5 or 6 seconds, and one would 
tune for the "sweet" spot.

Back in the days when I was doing it with an 8 level paper tape controller 
you would also want to send a complete set of commands to reset everything 
to a known state, such as MODE B say off, MODE A on, CW speed, 435.1 OFF, 
RTTY OFF, CODESTORE OFF.

Your biggest challenge will be to overcome the random wake up state where 
both transponders and the 435.1 are ON.  AMSAT badly needs a great 
benefactor to donate a few KW amplifiers and some big antennas for fixing 
AO-7 on the fly.

I can not find your email address here so I have cleaned this up and am 
sending it by the AMSAT BB.

And last but not least while your writing the sound card command generator 
include the functions so that one can test out the CODESTORE.  It would be 
wonderful to see if that box of really prehistoric CMOS stuff still works.

If you want anything else from me then email me direct please.

Good Luck

Larry
VA3LK

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