[amsat-bb] NO-84...operator error?

Jerry Pixton jpixton at shentel.net
Mon Dec 14 01:44:21 UTC 2015

Mark, et al

The PSK passband is about 3 KHZ. Your radio USB bandwidth may be the 
limiting factor.

Are you seeing the beacon at about 314 Hz if someone gets it keyed up?

I discovered today that if I just send idle tones (key up with no 
message) that the 31.5 baud detector circuit is much quicker to turn on.

I am confused by the question: Mark, what signal are you seeing in the 
psk waterfall? I assume this is a waterfall of the downlink audio? Then 
was this your signal?

If your radio uplink VFO is set at 28120000 Hz in USB, and I modulate 
with a 1500 Hz audio tone (however I generate it) I would expect to hear 
a 1500 tone on the FM or 1500 Hz on the PSK31 waterfall. This is 
ignoring any error in my uplink vfo and any translation error in the 
bird - both of which are real. The other big error is doppler.

But DopplerPSK is doing a reasonable correction of the modulation tone 
so that when you set a desired center frequency of 1500, you get close 
to that most of the pass with some noticeable error around TCA but still 
decodable. But if you are not doppler correcting your uplink signal all 
bets are off with the plus/minus 700 Hz tone shifts seen.

So I guess a test of how well your doppler correction is working is how 
close your downlink signal is to the target central tone you have set 
for the uplink?.

Jerry, W6IHG

On 12/13/2015 7:51 PM, Mark Lunday wrote:
> Again I tried to send through AO-84.  I was on 28120 with a  tone of 1.5
> kHz.  I saw nothing on the 435.35 downlink.  At all.  The 1932 UTC was good
> enough that I should have seen something.
> I was also not able to send a packet through on 145.825.  How wide is the
> passband for PSK on the uplink?
> Mark Lunday, WD4ELG
> Greensboro, NC  FM06be
> wd4elg at arrl.net
> http://wd4elg.blogspot.com
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Dr. Jerry R. Pixton, PIXOS Designs
jpixton at shentel.net

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