I didn't think to check his system for CPU usage or such. He's using a
RigBlaster.
A test procedure would very nice Joe
RRR
Mike W9MDB
On Wed, Jan 20, 2016 at 1:46 PM, Joe Taylor <j...@princeton.edu> wrote:
> Hi Mike,
>
> W9MDB wrote:
>
> Helping out somebody and he seems to have periodic problems decoding.
>>
>> These 3 wav files don't decode at all.
>> He does have good time sync
>> He does have 48kHz sampling.
>> Apparently things go well for him for a while and then decoding fails. So
>> there has to be something funky with the audio here that I don't see.
>>
>> They don't decode in 1.6.0 or 1.7.0 and definitely look like they should.
>>
>
> On close inspection, these signals do NOT look like they should decode.
> There are frequent glitches (interruptions) in the audio input stream, and
> this is bad.
>
> The essential clue is easily visible in the attached screen shot showing a
> portion of the spectrum for the file 160118_2048.wav.
> The horizontal light-blue streaks on the stronger JT9 signals are excess
> sidebands caused by interruptions in the stream of audio input. The
> interruptions cause phase discontinuities in the digital data presented to
> "symspec" for spectral analysis. The horizontal streaks are strongest in
> the strongest signal, but can often be seen (at exactly the same times) in
> the weaker signals as well.
>
> The effect is similar to "key clicks". In this case the discontinuities
> are caused by gaps in the audio input.
>
> Why is this happening? The most likely cause is that his computer is busy
> doing something else when it needs to be accepting audio data.
>
> If desired, I can spell out a test procedure for identifying such a
> problem -- or making sure that you don't have one.
>
> -- 73, Joe, K1JT
>
>
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