DSD picking up audio when no signal present

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scanphreak

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I have a strange thing going on recently and I haven't been able to pinpoint exactly what's going on. Lately while decoding a local 800mhz P25 system DSD will start to attempt to decode audio and partial words will come through. Only thing is the scanner is in SCAN when this happens. It's not picking up this signal from a channel programmed in the scanner.

When the scanner stops on an active channel, the DSD's audio is clear and readable. Then a minute later when no signal is present from the scanner (i.e. scanner is in scan mode) garbled audio will start coming through the computer's speakers from DSD.

I'm running a modified Radio Shack PRO-95
Computer is a Panasonic Toughbook using Ubuntu 10.04LTS
Audio is an iMIC with the Line In option selected
DSD 1,4,1 with melib 1.2.3
my command string is: dsd -i /dev/audio1 -f1
 

KC1UA

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Although I can't explain exactly why this happens, it is apparently "normal" for this software. I notice it quite frequently when using it. I receive a brief blurb of what sounds like garbled audio, maybe a second or so in length.
 

mancow

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It's in the documentation somewhere. I recall reading that the author said it will spit out blurbs of crap for no reason occasionally. It seems to happen about every ten minutes.
 

blantonl

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The scanner might be losing the control channel and while scanning the voice channels the discriminator audio might be sending a blip of digital voice to the computer.
 

scanphreak

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Well there is not control channel, I'm scanning 6 800 mhz frequencies in conventional mode, with the control channel not even programmed in. I've noticed that I'll get a good transmission, and a couple of minutes later while the scanner is just scanning (not stopped on a programmed frequency) DSD will start to blurt out garbled audio, sometimes it'll come in partially clear, meaning I can distinguish from a male or female. It's weird, it's never done this when listening to TRBO or Provoice in my area, but P25 it is.
 
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