Unitrunker analog audio quality issues, plus a question

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atomicthumbs

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Howdy. I've got Unitrunker set up with a pair of RTL-SDR dongles and Trunking Recorder, monitoring San Francisco's Motorola Type II system.

My audio seems plagued with incredibly obnoxious momentary dropouts, as demonstrated in the following recording: https://pinopsida.com/misc/unitrunker.mp3

It also has that odd crackling, which may have begun after I enabled the squelch at an appropriate value on all voice VCOs.

I suspect that the dropouts may be the fault of the dongle retuning while it's receiving, which brings me to my other question: is there any way to pin the center frequency of one receiver to keep it from retuning, or tell its VCOs not to pick up something that would lose the control channel?

With two receivers at 2.5 msps, I ought to be able to record the entire system, but the way things seem to be set up, I can only monitor up to eight channels, and only within one receiver's worth of bandwidth. Adding any voice VCOs on the receiver currently dedicated to the control channel causes it to tune the control channel out of its bandwidth.

The software can tell well enough when a channel is out of range of the receiver, but it doesn't seem to put that information to the good use it could!
 

SCPD

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I suspect that the dropouts may be the fault of the dongle re-tuning while it's receiving, which brings me to my other question: is there any way to pin the center frequency of one receiver to keep it from retuning, or tell its VCOs not to pick up something that would lose the control channel?
There was a bug a while back like this. The work-around was to set the first VCO to signal role. The program does not support "anchor" tuning.
 

atomicthumbs

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Hello thumbs;

What version are you using?
1.0.33.5, according to the file properties of uniform.exe.

There was a bug a while back like this. The work-around was to set the first VCO to signal role. The program does not support "anchor" tuning.
Does this mean I could add voice VCOs to the signal receiver (which currently has just the signal VCO) and it would automatically avoid tuning away from the control channel?
 

atomicthumbs

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Note that I've verified that both the high-pitched crackling and the dropping out happen with or without the audio being routed through Virtual Audio Cable. The squelch and deemphasis sounds don't affect either issue.
 

SCPD

QRT
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Does this mean I could add voice VCOs to the signal receiver (which currently has just the signal VCO) and it would automatically avoid tuning away from the control channel?
Correct. Signal role VCOs get priority over voice role VCOs.
 

atomicthumbs

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San Francisco, CA
I've tested it, and adding any voice role VCOs on the receiver with the signal VCO results in it tuning away as soon as it detects a call.

Any hints on the audio dropouts on calls?
 
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