Audio cuts out discriminator output - UBCD996T

Scotty
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Audio cuts out discriminator output - UBCD996T

Post by Scotty » Fri Aug 19, 2011 12:53 pm

Noticed this morning that when audio is received on my 996T the discriminator feed to UniTrunker drops to zero and it stops decoding. Signal goes back to normal and decoding commences again when the audio stops.

Nothing has been changed on the scanner or the computer. All settings appear normal. Could a damaged resistor in-line with the tap cause this? Having trouble thinking of another cause.

Any suggestions or thoughts appreciated.

Longreach
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Re: Audio cuts out discriminator output - UBCD996T

Post by Longreach » Fri Aug 19, 2011 2:11 pm

Hi all, Yeah sounds about right, the scanner will switch to the voice channel to take the audio and then switch back to the control channel when it ends.
cheers
Matt
VK2MRC

Scotty
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Re: Audio cuts out discriminator output - UBCD996T

Post by Scotty » Fri Aug 19, 2011 2:21 pm

Thanks longreach.

You reckon this is normal? I don't recall the scanner doing this previously, but I can't say I've really paid much attention in the past.

Longreach
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Re: Audio cuts out discriminator output - UBCD996T

Post by Longreach » Fri Aug 19, 2011 2:35 pm

Yeah quite normal, ive done the same thing with one of my GRE PSR500's using the PC Interface cable and leaving it on the wildcard (scan all on site) TG and the same occurs, it will watch the control channel data as normal till you get activity then you lose the data stream to unitrunker while the conversation occurs. its quite a pain and hence i dont do it anymore.
the only advantage ive found doing it with that method is while the GRE's are scanning and your on the 'Roam' feature( scanning strongest control channel) you know what site your on. the way you have it setup youll only see affiliations and background stuff while the site is in standby.
Might be best getting a cheapo analogue scanner and 'tapping' it still does the job quite well.
cheers
Matt
VK2MRC

citabria
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Re: Audio cuts out discriminator output - UBCD996T

Post by citabria » Fri Aug 19, 2011 3:03 pm

Its totally normal - remember theres only one receiver in a 996. It receives the CC until a voice call comes along, then it re-tunes to the voice channel. For the duraiton of the voice call, the receiver isn't hearing the CC.

Scotty
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Re: Audio cuts out discriminator output - UBCD996T

Post by Scotty » Fri Aug 19, 2011 6:17 pm

Thanks for the replies everyone. I've normally got several sites scanning at the same time, so that could be why I haven't really noticed it before. Only recently started running off one site at a time, and the whole one receiver inside thing now seems obvious. Will start using a second scanner to listen in.

soupbones
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Re: Audio cuts out discriminator output - UBCD996T

Post by soupbones » Sun Aug 21, 2011 11:46 am

Even when you scanning several sites its really only hopping from one to the other, and not monitoring them all at once. You only have one receiver in your scanner, so it can only listen to one thing at a time..regardless of who you set it up or what you think it is doing...

Longreach
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Re: Audio cuts out discriminator output - UBCD996T

Post by Longreach » Sun Aug 21, 2011 2:18 pm

Hi all, yeah and the pain with it hopping about is by the time unitrunker or Pro96.com gets itself setup on the data stream the scanner is off finding another channel. to do what you want to do unfortunately youll need several scanners to do it properly.
cheers
Matt
VK2MRC

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rustynswrail
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Re: Audio cuts out discriminator output - UBCD996T

Post by rustynswrail » Sun Aug 21, 2011 2:26 pm

Longreach wrote:Hi all, yeah and the pain with it hopping about is by the time unitrunker or Pro96.com gets itself setup on the data stream the scanner is off finding another channel. to do what you want to do unfortunately youll need several scanners to do it properly. cheers Matt
Having done probably hundreds of discrim mods, I would recommend the oldest scanner that you can get, why? Filtering. The older the scanner the less filtering or at least the slacker the filtering. Even baseband audio goes through some filtering process, therefore the less there is the better the BBA.

Also always use a 10k ohm resistor, it helps keep the signal clean.

My 2 cents worth.

R
Amateur Radio, when all other cures for insomnia fail!

Scotty
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Re: Audio cuts out discriminator output - UBCD996T

Post by Scotty » Sun Aug 21, 2011 5:16 pm

soupbones wrote:Even when you scanning several sites its really only hopping from one to the other, and not monitoring them all at once. You only have one receiver in your scanner, so it can only listen to one thing at a time..regardless of who you set it up or what you think it is doing...
Yep, but when it switched to the sites while scanning several at once I was used to seeing the signal on the site it had been on previously drop off, so I probably hadn't noticed that it did the same when it picked up audio. It was only when I started monitoring one site at a time that it drew my attention.

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