[PSAS Comm.] notes up, 2m LO problem thoughts

Andrew Greenberg andrew at uad.com
Thu Jun 23 11:50:39 PDT 2005


I posted some notes from Tuesday's tests: please go and read and edit:

http://psas.pdx.edu/CommWorkshop21June2005

OK, so what happened to our great new 2m receiver? I think something 
happened to cause all of this, and we just didn't notice when it happened.

Is the following timeline true?

1. We got the new 2m receiver working, and it seems to work great. SINAD of 
around -100 dB.

2. We did a council crest to mt tabor test of the 2m system, and with only 
2.5 W on the TX side, it worked great according to our notes. The GPS never 
locks on this test, which could be the ATV Or the ATV/2m interference 
problem. Have we ever seen GPS lock with the 2m on at this point? Maybe the 
harmonics are new after this test?

3. Something happens.

4. Our 2m receiver now has a SINAD of -85 dB and has lots of spikes, which 
may or may not have been there before.

Can anyone add anything to this? Maybe we should be looking for a bad 
solder joint on the receiver? Or do we need to do the tests with the 2m 
receiver screwed down to the airframe, or with the whole airframe?

Andrew



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    Andrew Greenberg - andrew at uad.com - 503.788.1343
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