SDRSharp with DSD+ confusion with P25 control channel freq

[brhmmr419]

Good Evening,

I am new to the SDR world but would like to think that I am tech savvy enough to set it up. I recently purchased a NESDR SMART solely for the purpose of listening to a single channel in Wise County, TX. With the cheapest scanners still being north of $600, I figured this would be the best route. I am specifically trying to listen to the Wise County Fire Dispatch which on RadioReference has a TalkGroup ID of 31001. I have installed SDRSharp and DSD+ and can get various VHF and UHF traffic no problem. I suppose my main issue is with figuring out the control channel frequency. Digital systems such as P25 phase 2 are still seeming quite foreign to me. From what I have researched even an SDR isn't enough for trying to listen to these systems. These are the control channel capable frequencies listed below but I could have sworn that it should have been in the 800mhz range. Any help on setting this up and or telling me that it won't be possible would be greatly appreciated. Thank you.

151.250c

154.2125c

155.265c

155.6325c

155.880c

 

[mtindor]

Those are the control channels. Only one can be a control channel at a time, but any given time the control channel could be switched to one of the other freqs. Is there any particular reason why you are using SDRSharp instead of the FMP/FMP24.exe that come with DSDPlus? Are you running the free version of DSDPlus off of DSDPlus – Digital Decoder ? If so, you would need to use FMP.exe. If you are running DSDPlus Fast Lane (paid version) you would use FMP24.exe

It's the combination of FMP.exe / DSDPlus.exe (free) or FMP24.exe / DSDPlus.exe (Fast Lane) that allow you to use DSDPlus to actually trunk track.

Otherwise, if you are using SDRSharp as your input with a virtual cable, you can't trunk track -- you can only park on one frequency.

It is easy to tell which of the frequencies above is the control channel. Only one of them would be transmittiing 24/7. And only one of them would provide all of the information regarding System ID, Site ID, Site NAC, peers/neighbors as well as show Group Call, Private Call and Data Call activity.

 

[Mobby1-Kenobby]

Hi, brhmmr419​

You could have a look at Unitrunker at this link: https://www.unitrunker.com/SDRs.html

Its free and may or may not work with your NESDR SMART.

Cheers

 

[dave3825]

I recently purchased a NESDR SMART solely for the purpose of listening to a single channel in Wise County, TX.

TalkGroup ID of 31001.

I have installed SDRSharp and DSD+

Trunked systems are best with SDRTrunk, OP25 (Linux), DSDPLus FastLane, DSDFME, Trunk Recorder (Linux) and Unitrunker (Phase 1 systems). SDR#

Chances are the DSDplus you have is the free version and I believe you would need 2 dongles with that as the FastLane version will let you use just one dongle. Since you only want one talk group, that's probably the best route to take.

From what I have researched even an SDR isn't enough for trying to listen to these systems.

Generally the dongles only cover 2.4 mhz and Wise is more than that. DSDPlus FastLane (paid) can handle that system no problem. Sdrtrunk would require an additional dongle or and Airspy or equivalent.

These are the control channel capable frequencies listed below but I could have sworn that it should have been in the 800mhz range.

Control channels can be a variety of ranges. Vhf 150/160 Uhf 400/500/700/800/900 Mhz

Hi, @brhmmr419​

You could have a look at Unitrunker at this link: https://www.unitrunker.com/SDRs.html

Its free and may or may not work with your NESDR SMART.

Cheers

System of interest is phase 2 operating as such. Unitrunker will show all activity but wont decode voice.

 

[brhmmr419]

@mtindor @Mobby1-Kenobby @dave3825 Thank you for all that information. I am on a very small volunteer fire department and the county switched to P25 phase 2 and we could barely afford enough radios for our trucks but not enough for each person to have a take home device. The app we use on our phones can sometimes be delayed by 4 minutes after tones drop and that is why I am experimenting to see if I can set up a scanner for an affordable price. I still haven't got it to work but I feel that I am a lot further than I was before. My next issue might be misconfiguration or antenna set up. I am 9 miles as the bird flies from the closest repeater/transmitter so that could be part of it as well.

 

[mtindor]

@mtindor @Mobby1-Kenobby @dave3825 Thank you for all that information. I am on a very small volunteer fire department and the county switched to P25 phase 2 and we could barely afford enough radios for our trucks but not enough for each person to have a take home device. The app we use on our phones can sometimes be delayed by 4 minutes after tones drop and that is why I am experimenting to see if I can set up a scanner for an affordable price. I still haven't got it to work but I feel that I am a lot further than I was before. My next issue might be misconfiguration or antenna set up. I am 9 miles as the bird flies from the closest repeater/transmitter so that could be part of it as well.

Looks like you have DSDPlus set to listen on a virtual cable, but you are running FMP (and not SDRSharp or something with the virtual cable)

If you are starting FMP / DSDPlus with batch files, please post what is in the batch files. If you are just running FMP.exe and DSDPlus.exe, please post any command line options you are using with those.

If you are running FMP.exe and DSDPlus.exe without a batch file (or with options in a batch file) you need to make sure that FMP and DSDPlus know how to communicate with each other.

fmp -o20000
dsdplus -i20000

The -o20000 in FMP will tell FMP to communicate with DSDPlus over TCP port 20000. The -i20000 will tell DSDPlus to listen for FMP on TCP Port 20000.

You should have a DSDPlus.txt file. Search that file for "Input/Output" and read about how to set up input/output between FMP/DSDPlus.

FMP-CC.bat and CC.bat are two batch files you should look at as well. As that is what you would typically run to get FMP/DSDPlus started.

Mike

 

[brhmmr419]

Looks like you have DSDPlus set to listen on a virtual cable, but you are running FMP (and not SDRSharp or something with the virtual cable)

If you are starting FMP / DSDPlus with batch files, please post what is in the batch files. If you are just running FMP.exe and DSDPlus.exe, please post any command line options you are using with those.

If you are running FMP.exe and DSDPlus.exe without a batch file (or with options in a batch file) you need to make sure that FMP and DSDPlus know how to communicate with each other.

fmp -o20000
dsdplus -i20000

The -o20000 in FMP will tell FMP to communicate with DSDPlus over TCP port 20000. The -i20000 will tell DSDPlus to listen for FMP on TCP Port 20000.

You should have a DSDPlus.txt file. Search that file for "Input/Output" and read about how to set up input/output between FMP/DSDPlus.

FMP-CC.bat and CC.bat are two batch files you should look at as well. As that is what you would typically run to get FMP/DSDPlus started.

Mike

Thank you. I ended up switching and utilizing SDRTrunk instead. It worked great. I need to look at what type of antenna I want to use for my home set-up and also my mobile for in my truck.

 

[slicerwizard]

Chances are the DSDplus you have is the free version and I believe you would need 2 dongles with that

For anyone coming across this thread in the future, DSD+ 1.101 doesn't trunk track P25 systems, doesn't decode P25 control channels, doesn't know what Phase II voice is, yadda yadda. That or I've gone senile...

 

[TomLine]

Good Evening,

I am new to the SDR world but would like to think that I am tech savvy enough to set it up. I recently purchased a NESDR SMART solely for the purpose of listening to a single channel in Wise County, TX. With the cheapest scanners still being north of $600, I figured this would be the best route. I am specifically trying to listen to the Wise County Fire Dispatch which on RadioReference has a TalkGroup ID of 31001. I have installed SDRSharp and DSD+ and can get various VHF and UHF traffic no problem. I suppose my main issue is with figuring out the control channel frequency. Digital systems such as P25 phase 2 are still seeming quite foreign to me. From what I have researched even an SDR isn't enough for trying to listen to these systems. These are the control channel capable frequencies listed below but I could have sworn that it should have been in the 800mhz range. Any help on setting this up and or telling me that it won't be possible would be greatly appreciated. Thank you.

151.250c

154.2125c

155.265c

155.6325c

155.880c

Look at the band range in SDR sharp band scope and the control frequency may be be in the center, but very active, quickly telling the remote radios what to do, and the other channels pop up less frequently but stay active longer as folks transcieve. I got mine to work. I remember using two rtl-sdr's and the audio was just okay but less than perfect for sure.

 

[mtindor]

For anyone coming across this thread in the future, DSD+ 1.101 doesn't trunk track P25 systems, doesn't decode P25 control channels, doesn't know what Phase II voice is, yadda yadda. That or I've gone senile...

Imagine that shiz! Goes to show how long it's been since I've used the free version lol