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<DIV>Jon Adams wrote:<BR><BR>>Good morning all -<BR>><BR>>I've been running HF APRS for over 10 years and as an HF Gate for nearly<BR>>that long. When I listen to the traffic, I hear stations high and low of any<BR>>one frequency, and if they're more than a few dozen Hz off, they don't<BR>>decode very well. (running Kam+).</DIV>
<DIV> </DIV>
<DIV>Or, alternatively, instead of a Kam+ you could use a </DIV>
<DIV>PC soundcard DSP program that can search across </DIV>
<DIV>a chunk of RF spectrum. Then you wouldn't have to</DIV>
<DIV>worry about their signal being exactly on frequency,</DIV>
<DIV>just reasonably close. And you can define "close"</DIV>
<DIV>yourself.</DIV>
<DIV> </DIV>
<DIV>I don't know if anyone has done this already, but it </DIV>
<DIV>wouldn't be too hard. With a typical SSB receiver you </DIV>
<DIV>could search for any AX.25 packets in the receiver's </DIV>
<DIV>bandpass (let's say 3 kHz). If you wanted to get fancy</DIV>
<DIV>you could even use something like an SDR-1000</DIV>
<DIV>or a Softrock-40 type receiver. This could digitize a</DIV>
<DIV>large (let's say 48 kHz) piece of the HF band and then </DIV>
<DIV>you could search over whatever range of frequencies you</DIV>
<DIV>wanted ( +/- a few Hz or +/- a few kHz ) for all of the </DIV>
<DIV>AX.25 Bell 202 packets. You're limited only by the</DIV>
<DIV>speed of your processor.</DIV>
<DIV> </DIV>
<DIV>Hasn't someone already written the "search-for-and-receive- </DIV>
<DIV>all-on-frequency-and-off-frequency-HF-packets" soundcard </DIV>
<DIV>demodulator program?</DIV>
<DIV> </DIV>
<DIV>Douglas KA2UPW/5</DIV>
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