DSDPlus Audio comes through control and not on voice with two RTL-SDRs (Nooelec R820T2) on Fast Lane

[Tekkie101]

I had a single RTL-SDR and was using fast lane to monitor the control and voice channels simultaneously using 1R.bat (DSDPlus -r1 -T -E -Pwav -i20001 >>1R-log.txt). There was a minor inconvenience of not being able to monitor the voice channels for groups I wanted to hear when the control channel couldn't be monitored because it was tuning to voice frequencies for undesired groups. As a result, I obtained a second RTL-SDR so that I could have one dedicated to monitoring the control channel and a second that could bounce between the voice channels. This way, I wouldn't miss data on the control channel that would result in missing conversations on certain group IDs because of other traffic on the P25 Phase II system. That, combined with a good list of groups and correctly set priorities, would give the desired functionality.

With the configuration below, I see the control channel being monitored and the voice channel idle, but audio only comes in on the control channel windows (which is odd) despite me having configured the windows to be CC and VC separately (not combined).

Configuration in order of what I open:

1. FMP24-CC.bat (FMP24 -rc -i2 -o20001 -P0.0 -b12.5 -f857.2125)
2. CC.bat (DSDPlus -rc -i20001 -v3 -wsl400.2 -wss100.200 -wel0.1 -wcl0.445 -wes400.520 >>CC.log)
3. FMP24-VC.bat (FMP24 -rv -i3 -o20002 -P0.0)
4. VC.bat (DSDPlus -rv -Pwav -i20002 -v3 -wsl400.210 -wss100.200 -wel172.522 -wcl528.0 >>VC.log)

I can hear transmissions very rarely with this setup.

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If I use FMP24-CC.bat with CC.bat (without FMP24-VC.bat or VC.bat), I get audio, but only about four groups out of the 10+ I had when I set this up a year ago when I was using 1R.



Interestingly enough, I can see other group IDs in the console window, but I'm not hearing them or seeing them pop up in channel activity.

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I can't easily identify what I've done wrong and, after many hours of testing with two different installations (separate folders), I'm seeking input from the community. Thanks in advance!

 

[lwvmobile]

Well, if it helps any, I used the guide found here when I was trying to figure this stuff all out. I honestly don't use DSD+ very much at all though aside from as a digital monitor, so I can't speak to how well this guide is, but it will give you a quick minimal setup at least, just skip down to the config part at the half way down.

DSD+ Trunking Tutorial

One of my favorite programs for decoding digital audio is DSDPlus. I’ve been using it a couple of years to dissect and decode SINGLE digital signals. Like for instance if I’m in the airport or airport hotel I can listen to DMR radio where the baggage handlers are talking to each other, or the...

www.hagensieker.com

Also, I found the set of bat files I used, much simpler than yours, but they don't include logging, so you may have to work that back in if you want it.

Configuration in order of what I open:

1. FMP24-CC.bat (FMP24 -rc -i2 -o20001 -P0.5 -b10 -f769.94375)
2. CC.bat (DSDPlus -e -fa -i20001 -rc -OM NUL)
3. FMP24-VC.bat (FMP24 -rv -i3 -o20002 )
4. VC.bat (DSDPlus -fa -rv -o1 -i20002 -OM NUL)

Somebody will probably come around and have a much more thorough diagnosis of what's going on with your bat files though I'm sure.

 

[Tekkie101]

Well, if it helps any, I used the guide found here when I was trying to figure this stuff all out. I honestly don't use DSD+ very much at all though aside from as a digital monitor, so I can't speak to how well this guide is, but it will give you a quick minimal setup at least, just skip down to the config part at the half way down.

DSD+ Trunking Tutorial

One of my favorite programs for decoding digital audio is DSDPlus. I’ve been using it a couple of years to dissect and decode SINGLE digital signals. Like for instance if I’m in the airport or airport hotel I can listen to DMR radio where the baggage handlers are talking to each other, or the...

www.hagensieker.com

Also, I found the set of bat files I used, much simpler than yours, but they don't include logging, so you may have to work that back in if you want it.

Configuration in order of what I open:

1. FMP24-CC.bat (FMP24 -rc -i2 -o20001 -P0.5 -b10 -f769.94375)
2. CC.bat (DSDPlus -e -fa -i20001 -rc -OM NUL)
3. FMP24-VC.bat (FMP24 -rv -i3 -o20002 )
4. VC.bat (DSDPlus -fa -rv -o1 -i20002 -OM NUL)

Somebody will probably come around and have a much more thorough diagnosis of what's going on with your bat files though I'm sure.

Thank you for taking the time to contribute. I did reference the link you sent during my initial Google-fu. What's crazy is that it's working and I can hear clear audio, but not with the configuration I expected and only for 4-6 groups (not the 15+ I'd expect and not the 2 I'm looking for).

I'm happy to take out recording but it appears both of our batch files are using parameters that specify control and voice separately, which interface to use, which port to use (differing by one) and you have a different bandwidth than I do, though I read it's supposed to be 12.5 and not 10. I'm unfamiliar with '-OM NUL' or '-fa'.

 

[cg]

Did you try reading the Notes or to use the Help shortcut to show the various options?
I prefer a paper copy when I am tweaking the batch files so I created a batch file to make a Help file each time a new version comes out and then I print it. You can put this in a batch file and run it:
DSDPlus -h >DSDPlus_Help.txt

You can change the "DSDPlus" to FMP24 or FMPA, etc

chris

 

[Tekkie101]

Did you try reading the Notes or to use the Help shortcut to show the various options?
I prefer a paper copy when I am tweaking the batch files so I created a batch file to make a Help file each time a new version comes out and then I print it. You can put this in a batch file and run it:
DSDPlus -h >DSDPlus_Help.txt

You can change the "DSDPlus" to FMP24 or FMPA, etc

chris

I did look at the documentation both prior to and after opening this thread. I learned that -OM NUL is disabling mono output to a file and that -fa is auto-detecting the decoder protocols.

Nevertheless, the configuration is working as I'm hearing clear audio. It's just not behaving as expected where one is control and one is voice. That's what's really confusing.

I revised my batch files to remove recording, even though that's not really a factor. I open FMP24-CC.bat and CC.bat and I have audio without opening FMP24-VC.bat or VC.bat.

Screenshots of DSD+ CC Event Log and console:

​

Console	Input	Output
Decoder	Control	Misc

I did notice that the visualizer shows a large grey bar with some RF in that bar when I hear a voice. The red arrow in this screenshot is the control channel and the red box is when receiving audio. It appears it's listening to one of the frequencies in the system:



Here's a video of the console while receiving voice:

https://i.gyazo.com/37a0e8224ff7201384ca3954f9fce7d3.mp4

Note multiple talkgroup IDs appear while listening to a single transmission. When they stop transmitting, you see the chunk of text at the bottom and it says channel released. The goal is for the control receiver to monitor all of this traffic and stop voice transmissions for lower priority channels when it detects something higher priority, or to skip certain talkgroups altogether.

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FMP24-CC.bat now contains:
FMP24 -rc -i2 -o20001 -P0.0 -b12.5 -f857.2125
(role is control, interface 2, output on port 20001, no frequency correction, bandwidth filter 12.5 kHz, control frequency 857.2125)

CC.bat now contains:
DSDPlus -rc -i20001 -v3 -wsl400.2 -wss100.200 -wel0.1 -wcl0.445 -wes400.520 >>CC.log
(role is control, input on 20001, verbosity level 3, location specifications for wss, wel, wcl, and wes, output to CC.log)

FMP24-VC.bat is not open, but is configured as such:
FMP24 -rv -i3 -o20002 -P0.0
(role is voice, interface 3, output on port 20002, no frequency correction)

VC.bat is not open, but is configured as such:
DSDPlus -rv -i20002 -v3 -wsl400.210 -wss100.200 -wel172.522 -wcl528.0 >>VC.log
(role is voice, input on port 20002, verbosity level 3, location specifications for wss, wel, wcl, and wes, output to VC.log)

--

If I open FMP24-VC.bat and VC.bat, there are no signs of any activity at all:

 

[slicerwizard]

You have CC FMP24/DSD+ sitting on a voice channel. You're supposed to be parked on the control channel.

 

[Tekkie101]

You have CC FMP24/DSD+ sitting on a voice channel. You're supposed to be parked on the control channel.

Good afternoon! Thanks for reading over the post. I'm interested to see how I can tell the instance of DSD+/FMP24 I'm using for control to stay as a control. The batch file used to start FMP24 says "FMP24 -rc -i2 -o20001 -P0.0 -b12.5 -f857.2125". 857.2125 is the control frequency. Within DSD+, the control menu is set to CC Monitor, so it's not being instructed to do anything with voice. What's your recommendation to have it not park on a voice channel? I know everything works properly and that it's a configuration issue, but I cannot figure out where that configuration item should be modified. The FMP24 console says "Initial frequency set to 857.212500 MHz" when I start it:

Current working directory is "XXX"
SDR sampling rate = 2.400 MHz
Spectrum window width: 1024
FFT size: 32,768
Spectrum update rate: 10 Hz
Step size table:  5.000  6.250  7.500  12.500  15.000  25.000  100.000
DSD+ path is "XXX"
Primary frequency list: '.\FreqList.csv'
Secondary frequency list: '.\FreqList2.csv'
Database search distance: 99.90 miles
Base latitude/longitude: 19.7163 -155.6241
Role is control/rest channel monitor;
Auto-starting control/rest channel following mode
Using RTL SDR device #2
Using TCP port #20001
PPM correction set to 0.0
12.50 kHz RF bandpass filter selected
Initial frequency set to 857.212500 MHz
Optimizing FFT calculations...  done.
SDR device count = 3
SDR device #1 is in use
SDR device #2 serial string = '00000001'
SDR device #3 serial string = '00000001'
Found Rafael Micro R820T tuner
Found Rafael Micro R820T tuner
Tuner type=5 (R820T)
Serial string = '00000001'
Sampling rate set to 2.400000 MHz
Frequency correction factor = 0.0 PPM
No frequency data files found
Listening on TCP port 20001
Trunk control/rest channel following active
Accepted local connection on port 50769

When voice plays, the frequency changes from 857.2125 to 857.2125 +###Hz or 857.2125 -###Hz, showing it's changing frequencies to follow the voice:

https://i.gyazo.com/f962ea8a4d96751bf1588985d88273d8.mp4

 

[slicerwizard]

I would manually tune CC FMP24 to the current control channel. After CC DSD+ starts decoding the system properly, I'd go into the Control menu in CC DSD+, click on Startup Options, then on Load Current Trunking System. I'd also verify that Hunt For Lost Control Channels is checked. I'd then shut everything down and restart it to test.

 

[Tekkie101]

I would manually tune CC FMP24 to the current control channel. After CC DSD+ starts decoding the system properly, I'd go into the Control menu in CC DSD+, click on Startup Options, then on Load Current Trunking System. I'd also verify that Hunt For Lost Control Channels is checked. I'd then shut everything down and restart it to test.

I edited my response while you were responding to add more detail, but I did confirm FMP24 is set to 857.2125. It seems to automatically move frequencies, as it shows adjustments with + ##Hz. I did just notice that the FMP24 console shows a frequency other than 857.2125 (857.206250), so it's re-tuning itself from what the console shows it's using. I've seen the variation in frequency go from 857.21250- 85Hz as high as 857.21250+ 212 Hz.The name of the command prompt console window for FMP24 seems to be fixed on 857.206250.





This is progress, but I'm still unsure of how to correct it.

EDIT: I just restarted FMP24-CC.bat and confirmed it starts on the right frequency:


Also, the startup options don't permit me to load the current trunking system:

 

[slicerwizard]

Based on your screen shots,

CC FMP24 says that the signal on 857.2125 is very weak and intermittent. P25 control channels are continuously active/transmitting

CC DSD+ says that the signal on 857.2125 is NOT a control channel signal.

You can't tell CC DSD+ to load the current trunking system at startup because you're not monitoring a trunking system. You have to be monitoring the control channel.


Either 857.2125 is not a local control channel (how far away is the transmitter from you?) or your dongle is way off frequency and isn't actually monitoring 857.2125. Post a link to the RRDB entry for the site.

 

[Tekkie101]

Based on your screen shots,

CC FMP24 says that the signal on 857.2125 is very weak and intermittent. P25 control channels are continuously active/transmitting

CC DSD+ says that the signal on 857.2125 is NOT a control channel signal.

You can't tell CC DSD+ to load the current trunking system at startup because you're not monitoring a trunking system. You have to be monitoring the control channel.


Either 857.2125 is not a local control channel (how far away is the transmitter from you?) or your dongle is way off frequency and isn't actually monitoring 857.2125. Post a link to the RRDB entry for the site.

Interesting! Thanks for taking a look at this. I do appreciate it.

Cobb Regional Radio System Trunking System, Various, Georgia

Cobb Regional Radio System Trunking System Profile

www.radioreference.com

Cobb Regional Radio System
Site 1, Cobb County Simulcast

I live very close to the center of the circle and the audio I do receive is about 8/10 with only a few modulation sounds:

 

[cg]

A system I monitor has a channel that is almost constantly streaming data as well yet it is not the control channel.
If you look at the bottom of the Event Log window, you have:
P25 NAC: 170 NL: 17D-1.4 17D-1.5 17D-1.6 17D-1.7 17D-1.8
That is an indication you are NOT on the control channel. You want to see:
P25 Site:BEE00.17D-1.1 NAC: 170 NL: 1.4 1.5 1.6 1.7 1.8

I would suggest you go through the list of frequencies one at a time looking for the correct control channel.

 

[slicerwizard]

You can click on any visible carriers in FMP24 and see what DSD+ thinks.

 

[Tekkie101]

A system I monitor has a channel that is almost constantly streaming data as well yet it is not the control channel.
If you look at the bottom of the Event Log window, you have:
P25 NAC: 170 NL: 17D-1.4 17D-1.5 17D-1.6 17D-1.7 17D-1.8
That is an indication you are NOT on the control channel. You want to see:
P25 Site:BEE00.17D-1.1 NAC: 170 NL: 1.4 1.5 1.6 1.7 1.8

I would suggest you go through the list of frequencies one at a time looking for the correct control channel.

You hit the nail on the head with this. Thank you for your guidance. I had no idea that the information at the bottom of the DSD+ event log was providing useful information. I went through each frequency and had zero activity, until I reached the frequency listed as the alternate control channel, 856.2125. The second I tuned to this frequency, everything lit up like a Christmas tree in a way I've never seen before. Here's a video: https://i.gyazo.com/d66f339ab6377ccf435f0cdc7c98dfe7.mp4

This is incredible. Files I thought weren't relevant are now being populated, like networks, sites, and all sorts of stuff. The audio quality is cleaner, too. This is absolutely incredible. One radio monitors the control channel and sees quite literally a constant flow of data (the console window is unreadable because it moves so fast) and the voice control is accurately picking up data and tuning as needed based on priority. This is EXACTLY what I was looking for and I am greatly appreciative. I can't believe I was missing out on this functionality when I thought I had it working a year ago. Even my groups file wasn't working correctly because the network said 0 but had the right group IDs. My list now within 2 minutes is already four times larger than it was before. It's working perfectly and this was all because of the wrong control frequency.

I see in the channel activity screen that 856.2125 is the control channel and 857.2125 is listed as 'scc', which I thought was secondary control channel but after a quick search appears to be a single-channel converter used for analog radios. I see that there is often traffic on that frequency, which is why I was hearing regular voice traffic. RadioReference appears to have the frequencies identified incorrectly.

Thank you so very much! Are there any recommendations for making minor enhancements or improvements to the configuration? The gain is at 49.6 with BW at 9.5 on a 6.25 step. The control channel FMP24 CC window is now showing 856.2125-### Hz. The number hovers around 260, give or take 5 Hz.

 

[slicerwizard]

The only enhancement would be to better set the RF gain, but you haven't provided a screen shot.

Also, as a premium RR subscriber, you can download system data to populate some of the DSD+ data files with stuff like (IIRC) site names and group names.

 

[MCotty]

Hi I noticed in the listing above all 3 devices listed have the same serial number will that work. I have mine set to different ones like 1,2,3

 

[cg]

For basic setups, it doesn't matter as DSDPlus will use them in the order they are seen. However you can choose which SDR gets used for which signal.
For example, I have a number of systems I want to monitor. I use 2 directional antennas in the 7/800 MHz range and another antenna for a 400 MHz system. So I need a certain SDR to start with a certain batch file because of the antenna attached. So I use different serial number SDRs and batch files linked to those.

chris

 

[Tekkie101]

The only enhancement would be to better set the RF gain, but you haven't provided a screen shot.

Also, as a premium RR subscriber, you can download system data to populate some of the DSD+ data files with stuff like (IIRC) site names and group names.

Here's a video of both the control channel (top) and voice channel (bottom):
https://i.gyazo.com/54ed6f044ef1430d7e761fee70f455a4.mp4

I did populate the aliases and I now see the correct names for each group ID. Thanks.

-

Some other quick and not very important questions, if you (or anyone else) knows the answer off the top of your head... Do you happen to know the cause or significance of any of these oddities I see pop up?


(No audio and it shows lockout. The target isn't a talk group but a direct radio number, it seems. This number changes multiple times per second and usually only appears for a few seconds at a time)

-



What's causing these denials and refusals? What are they?

-


Are the registrations and deregistration the units being powered on and off and notifying the system of that action?

-


Why are some set to lockout (L/O) automatically? I cannot click these to change them like I can others, DSD+ claims there are no lockouts to reset when I try to reset all lockouts, and the groups file shows this is set to Normal with a priority of 50, which is the default.

 

[slicerwizard]

View attachment 101765
(No audio and it shows lockout. The target isn't a talk group but a direct radio number, it seems. This number changes multiple times per second and usually only appears for a few seconds at a time)

Some sort of data calls. Could be AVL updates.

View attachment 101766
View attachment 101767
What's causing these denials and refusals? What are they?

They're radios that aren't authorized to be on the network, for whatever reasons, or possibly not authorized to be on that site.

View attachment 101768
Are the registrations and deregistration the units being powered on and off and notifying the system of that action?

That, or changing talkgroups, or switching to/from conventional channels, or responding to an "Are you still there?" query.

View attachment 101769
Why are some set to lockout (L/O) automatically? I cannot click these to change them like I can others, DSD+ claims there are no lockouts to reset when I try to reset all lockouts, and the groups file shows this is set to Normal with a priority of 50, which is the default.

The voice call is encrypted and you don't have Follow Encrypted Voice Calls checked, so you effectively locked it out.

 

[Tekkie101]

Some sort of data calls. Could be AVL updates.


They're radios that aren't authorized to be on the network, for whatever reasons, or possibly not authorized to be on that site.


That, or changing talkgroups, or switching to/from conventional channels, or responding to an "Are you still there?" query.


The voice call is encrypted and you don't have Follow Encrypted Voice Calls checked, so you effectively locked it out.

Thanks for the information! I assume there's no point in following encrypted channels because you wouldn't hear them anyway, so the current setup is fine as is?