Re: [amsat-bb] PSK 31 on AO-40

[kevin schuchmann <kschuchm@xxxxxxxxxxx>]

On Saturday 01 November 2003 07:34, Rick Vidmar - K9KK wrote:
> I have run PSK31 on AO40 successfully.
> My program, TruTTY, has a built in AFC.  Maybe that's why, but I would
> think that all the programs do ???.  The only problem I've had is when
> RUDAK was turned on and produced a warble in the L1 receiver.  L2 did not
> have the warble problem.  Hopefully I don't have that backwards :-)
>


Hi Rick,
   your real close, RUDAK did cause the warble on L1, but it also did on L2 
but it was to such a lessor degree that no one really noticed it...

it was discussed many times and was always thought to be radar or something 
else....

   turns out that when RUDAK was not doing housekeeping chores it would drop 
into "sleep" mode, well this constant and random on-off was causing voltage 
spikes on the dc buss, the same buss the L receivers use, the receivers are 
sensitive it seems to voltage change so their frequency was being shifted all 
over the place... and then you got the warble.

     I had made wavs and taken pics of what it was doing and the RUDAK guys 
figured it out and added a "no-op" command or something to keep the 
processors running and out of "sleep" and thus the current drain became  
stable so the voltage buss would not effect L band receivers.

  Even with RUDAK off there is still something shifting the L1 receiver 
around,  if you send a steady carrier and then watch it on a audio spectrum 
display and narrow your range down,( I use 910 Hz to 1300Hz  with a 1100Hz 
carrier), you will see the L1 receiver shift about 10 Hz every couple 
seconds, right now the pattern has been constant, so it might be the panel 
BCR's shifting it or something else, their have been times when the pattern 
changes and gets real interesting... only the designers and builders would 
know what might be causing this...

what I'm wondering is if an  abrupt 10Hz shift would effect some of the 
digital modes? digital sstv for example or digital voice for example? 

73
Kevin WA6FWF



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