DSD+ Noise (Data Bursts)

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rkillins

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I am using DSD+ Fastlane edition with two RTL-SDR dongles. One is set for control of a Cap+ system, and the second a voice.
As of now, my control is not decoding (not active control channel), but I am getting an annoying burst of static. I don't know where this signal is coming from, or why I am hearing it as the voice control (to my knowledge) hasn't been tuned to a frequency to be picking this up?

Does the voice control VFO stay on the last frequency it was last tuned to whether or not fmp24-vc is controlling it anymore? I do know that when I was decoding the system when the control channel was active (I think I'm missing a frequency as none of the known are broadcasting it) I was hearing the burst of data (similar to what I am hearing now) despite not sending audio from my CC VFO to the speakers.

Actually, as I type this, the CC has returned to the frequency (451.5750). I see the pulsing on the scope. Sometimes the data burst sound accompanies the pulsing, whether associated to that control channel, or it's the same interfering burst I hear when the CC isn't active.

I'm wondering if it isn't some interference. The data burst seems to match another Cap+ control channel in the area of 451.4875.

So in a nut shell, why am I getting this data bursting when there is no voice being transmitted? If it's interference, is there a way I can eliminate it?
 

rkillins

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I don't know. I don't think so. It's only this particular system that I have this problem, everything else I monitor with DSD+ is fine.
Where could I look?

My DSD+ CC is setup as CC Monitor, Output is speakers, No digital voice synthesis (even switched to CABLE input, I still hear the data bursts)
My DSD+ VC setup is VC Monitor, Output is speakers, Synthesize all digital voice.
 

cg

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Cap+ does not have a control channel. It has a Rest Channel. If you are on it, you will see the channel number and under "Target" see Rest.
Of course you will hear the data noise if you point the CC output to the speakers. You need to point it to the VC. Or simply use a single dongle.
The program provides for TCP linking of FMPx and DSDPlus. i1 and o20001 then your DSDPlus gets i20001 o?(speakers)

chris
 

ScubaJungle

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I think it would be easier to use a single dongle, with combined CC/VC decoding. Open FMP24-CC.bat and CC.bat/1R.bat (either one) and switch to "combined CC/Voice channel". Also, your bandwidth may be too tight.
 

rkillins

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Thank you so much everyone. I was hoping it was, and it was, just a simple setting adjustment. I am relatively new to DSD+ and still learning what each setting is, when and how they are applied, and the consequences of each.

One thing that has been challenging for me to understand is the combination of hardware/software for listening to various systems.
ie when do I need to use a combination of FMP24_CC /CC and FMP24_VC / VC, versus a single dongle for both C and V? And VC over R?

If I run one instance of DSD+ with FMP24_CC both control and voice, dose that do the same as having a dual dongle setup on that system?

And if I may hijack my own thread ... it's driving me nuts that it appears I'm losing my REST channel. The CAP+ CC Channel Activity Window has REST next to the frequency (454.0750), but the FMP24 scope isn't pulsing, and the DSD+ Event Log is just endlessly scrolling through the three frequencies I have for that system in the frequencies file.

I don't know how to find that missing frequency(ies). I'm searched TAFL for the frequency know, and did additional searches based on both licensee and call sign and all it returns is 3 licensed frequencies, which are in my file.
 
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cg

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Two SDRs with some types of systems will allow the priority settings to interrupt a conversation and go to a different talkgroup. Some systems have date streamed in the voice channel that indicates other active channels but some don't and therefore require the CC to be monitored all the time for this feature to work properly.
 

rkillins

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I have done this to an extent, but they (obvious ones) have for the most part been accounted for in other systems. I'm not sure how far outside the spectrum I should be looking though. The system I'm fighting with is this one.
 

slicerwizard

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One thing that has been challenging for me to understand is the combination of hardware/software for listening to various systems.
ie when do I need to use a combination of FMP24_CC /CC and FMP24_VC / VC, versus a single dongle for both C and V? And VC over R?
You never have to run separate CC/VC copies. It's really only on busy non-P25 trunking sites where prioritized trunking might benefit from a full CC/VC setup. But that's only if you've actually modified group priorities for the users that are important to you.

And if I may hijack my own thread ... it's driving me nuts that it appears I'm losing my REST channel. The CAP+ CC Channel Activity Window has REST next to the frequency (454.0750), but the FMP24 scope isn't pulsing, and the DSD+ Event Log is just endlessly scrolling through the three frequencies I have for that system in the frequencies file.

I don't know how to find that missing frequency(ies). I'm searched TAFL for the frequency know, and did additional searches based on both licensee and call sign and all it returns is 3 licensed frequencies, which are in my file.
I assume you're dealing with a UHF Cap+ site; if so, you need to check 410-415, 420-425, 450-455, 460-465. It's a hell of a lot easier if you drive to the site - strong local carriers are dead easy to find. But first, I'd verify (by manually tuning to each known site channel) that you're not just dealing with a weak rest channel signal that's causing DSD+ to miss the pulses. And it wouldn't hurt to enable DMR decoding only, i.e. disable all other protocols, while monitoring Cap+.
 

rkillins

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Thanks Slicer!
You never have to run separate CC/VC copies. It's really only on busy non-P25 trunking sites where prioritized trunking might benefit from a full CC/VC setup. But that's only if you've actually modified group priorities for the users that are important to you.
Really??!! So all this time I've been doing unnecessary work? Wow. Just one instance of DSD+ then set to both control and voice will do it?

I assume you're dealing with a UHF Cap+ site
You bet!

if so, you need to check 410-415, 420-425, 450-455, 460-465.
So, the three frequencies that are known and listed in the gvt. database are 451.5750, 452.4250 and 454.0750. Would the presumed missing frequency(ies) be in the 450-455 portion of the band, or could it be an any? The reason I ask is because the gvt. database also has frequencies of 456.5750, 457.4250, and 459.0750 listerd, but they seem a bit out of place and they have been for the most part quiet.
 

slicerwizard

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Thanks Slicer!

Really??!! So all this time I've been doing unnecessary work? Wow. Just one instance of DSD+ then set to both control and voice will do it?
Uh huh.

So, the three frequencies that are known and listed in the gvt. database are 451.5750, 452.4250 and 454.0750. Would the presumed missing frequency(ies) be in the 450-455 portion of the band, or could it be an any?
You can't rule out anything.

The reason I ask is because the gvt. database also has frequencies of 456.5750, 457.4250, and 459.0750 listerd, but they seem a bit out of place and they have been for the most part quiet.
It would've been nice if you told us what system/site you're trying to monitor. I assume it's Bearcom Kitchener. If so, it's not that likely to have more than the three listed carriers. Have you shown us your work (your .frequencies file)? Have to get all the steps right.
 

rkillins

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Hi Slicer ... yes, it is Bearcom Kitchener.
I went back to TAFL and broadened by search criteria. Originally I used the Callsign of the frequencies I had, CGN489, which returned 3 frequency pairs. I then searched by station location field "KITCHENER, ON - 315 MARGARET STREET " Again, just the three frequency pairs.

A search for "315 Margaret Ave" netted me the 4th frequency. 463.6875 (Ch. 5/6). A different callsign, and a slightly different station location.
 
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