DSD+ with 396xt

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dubs0980

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Hey guys I'm a total DSD noob but I'm trying to set things up with my 396xt. I've got DSD+ and lame_enc.dll in a desktop directory. It is on a macbook running parallels with windows xp. I've got the 3.5mm output hooked up to an input on the macbook and the 396xt set to my local P25 control channel. Input level on the DSD+ command prompt heading show lvl=100% but data doesn't scroll it just says Mono audio decoding initiated press esc to exit. The only key that works is "R" for record. It does indeed record .wav files to the DSD folder but its just data and nothing is decoded. Thats basically all I've done. No tweaking or changed settings.I'm sure I've missed a vital (and hopefully simple) step somewhere. Any ideas how to make this work? I really appreciate any help. My end goal is to decode a local mototrbo.
 

Forts

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You mention 3.5mm hooked up... where? Headphone jack? If so, that won't work... you need a discriminator tap on the radio.
 

br0adband

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Unfortunately, you can't just use the earphone/headphone output as a discriminator tap; the audio is way too filtered for it to be of any use by the time you pipe it into a line-in or mic input on a computer for DSD+ to make use of it, that's one reason the technical term for a discriminator tap would be a baseband audio tap because that's the raw unfiltered signal a program like Unitrunker or DSD+ and even the original DSD requires to function correctly.

The only actual option would be to add a discriminator tap on the 396XT and that means opening it up and doing a bit of tinkering (either direct soldering or perhaps using some very tiny alligator clips) - now, since I don't own a 396XT personally everything that I just said is based on the research I just did for a few minutes about the 396XT and a discriminator tap so if I'm mistaken here someone will point that out and I'll just chalk it up to my own ignorance and a failure to find the relevant info. ;)

But I'm pretty sure the only scanner on the market (technically it's not since GRE is out of business) that can provide an actual proper discriminator output through the earphone/headphone jack is the GRE PSR-800 - would have been awesome for Uniden to add that specific feature to the new 436 and 536 scanners just becoming available right about now but afaik they didn't, sadly.

I myself have never ever had success with any scanner of any kind providing a usable signal off the earphone/headphone jack to mimic what an actual discriminator tap provides.

But I could be wrong, I'm just sayin'... :p

EDIT:
Ok, so I was correct about the earphone/headphone jack, HOWEVER... the 396XT can pipe a signal through the USB connection that Unitrunker can make use of, even so you're still basically stuck in the sense that it's not a true baseband audio signal that DSD+ requires - it's a serial data stream and not audio, and there's no proper way to convert it from the USB stream to something DSD+ can make use of so again, that's that.
 
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dubs0980

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Ah well that explains it. Also explains why there is so little info with the 396xt and DSD. You guys are great. Thanks for letting me know. Now i might pick something up some hardware that will let me play with this. Seems fun.
 

br0adband

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Ah well that explains it. Also explains why there is so little info with the 396xt and DSD. You guys are great. Thanks for letting me know. Now i might pick something up some hardware that will let me play with this. Seems fun.
That's why there's so much interest in SDR these days because you can - for roughly $10-20 spent out of pocket - get a "cheap USB TV tuner" and when that device is coupled with DSD+ (or DSD since it's still useful as well) you end up with the potential to monitor digital mode communications that no scanner on the planet is capable of currently and maybe never will.

Yes you can tap most modern scanners if you have the patience and the skill but, why risk damaging a device like the 396XT that costs ~$500+ when you can spend a few bucks and end up doing a whole helluvalot of cool stuff that scanner just can't do by itself?

I mean really... how cool is that? :D
 

dubs0980

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Very. I'm interested in the HackRF when it comes out but is there a setup available now you recommend? It seems these tuners come and go.
 

br0adband

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Better off doing some research yourself I suppose, there are a few threads in the Software Defined Radio subforum with a lot more info, in fact one of them was just started yesterday I think with someone asking how to get started and some of us tossing out the info - it's probably not a good idea to pollute this particular thread with info about SDR too much, seems to be a big no-no around here. ;)

Head over to that subforum here
 

dubs0980

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Just coming up for air.... I'm hooked. Big learning curve though. Reminds me when I first got the scanner and was programming everything,
 
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