Help with DSDPlus Fastlane and NXDN 4800

[R0am3r]

Ok, I am stumped. When I use DSDPlus Fastlane with 2 RTL-SDRs, I can easily monitor a NXDN 4800 system. This is my *working* batch file:
Start CMD /c FMP24.exe -i1 -o20001 -P0.0 -f150.8675 -b4
Start CMD /c DSDPlus -rc -fa -i20001 -v3 >>cc.log
Start CMD /c FMP24.exe -i2 -o20002 -P0.0 -rv
Start CMD /c DSDPlus -rv -fa -o1 -i20002 -v3 >>VC.log

When I switch to using 1 RTL-SDR, my batch file (shown below) fails to play the audio from the NXDN 4800 voice channels. I see the group calls in the DSDPlus window, but FMP24 never changes to voice channels and I never hear the audio transmissions.
Start CMD /c FMP24.exe -rc -i1 -o20001 -P0.0 -b4 -g33.8 -f150.8675
Start CMD /c DSDPlus -r1 -e -T -E -Pwav -i20001

So here is the rub. When I start the same 1 RTL-SDR batch file, and change frequency to my local P25 system (and increase bandwidth to 9.5), the 1 RTL-SDR system works perfectly (of course). If I switch the frequency (with appropriate bandwidth) to a local Ham DMR system, it also works perfectly. Why doesn't it work on NXDN 4800?

I posted something similar to the NY Mobiletech forum and made the corrections as suggested. Unfortunately, I was incorrect about the fix and it still doesn't work. Also note - I have populated the DSDPlus.networks, DSDPlus.sites, and DSDPlus.frequencies files. DSDPlus seems to read these files properly (i.e. no errors displayed).

Any ideas of what I am overlooking?

 

[GTR8000]

The DSDPlus command line parameters are quickly becoming a thing of the past with the latest releases. Your best bet it to remove as many of the parameters as possible, and use the new menu system in the Event Log window to set the options in real time. They will be saved when you exit the program.

DSDPlus -i20001

Start out with just that, then go through the menu to set the options. Try setting it up exactly as shown here, except of course enable NXDN4800 instead of P25 in the Decoder section. You can also uncheck Follow Encrypted Voice Calls in the Control section.

 

[slicerwizard]

When I switch to using 1 RTL-SDR, my batch file (shown below) fails to play the audio from the NXDN 4800 voice channels. I see the group calls in the DSDPlus window, but FMP24 never changes to voice channels and I never hear the audio transmissions.

Use the DSD+ menus to verify settings like voice call following, monitoring threshold, etc.

 

[R0am3r]

I'm starting to believe that DSDPlus Fastlane does not properly decode a NXDN 4800 system using a single RTL-SDR. Despite trying all sorts of possibilities, I still have no audio when I see a valid Group Call. If I switch back to using 2 RTL-SDRs, it works perfectly.

These are instructions for a one RTL-SDR:
FMP24.exe -o20001 -P0.0 -f153.545
DSDPlus -i20001

These are the DSDPlus settings I am using:
Input
Use TCP Linking
No Source Audio Monitoring

Output
Speakers
Synthesize all digital voice
Per-Call Recording (wav)

Decoder
Noise Filter
Shaping Filter
Decode NXDN4800

Control
Combined CC/VC Monitor
Hunt for Lost Control Channels
Voice/Data Call Following
Set High Priority Override for New Talkgroups
Group Voice Calls: Normal Handling
Private Voice Calls: Normal Handling
Data Calls: Normal Handling

Window
Event Log = Normal Color Scheme
Channel Activity = Normal Color Scheme
Site Loader = Normal Color Scheme
Source Audio
Source Audio Window (checked)
Overlay Eye Pattern (checked)
Normal Color Scheme
Current/Seen Groups (unchecked)
Current/Seen Radios (unchecked)



Misc
Enable Keyboard Commands
Imperial
Alert on All Voice Calls
Show All Traffic and Background Events
Automatically Check for Updates


This is my DSDPlus.networks file:
; DSD+ networks file
;
; you can edit this file while DSD+ is running
;
; line format: protocol, networkID, "network name"[, TIIIareaLength]
NEXEDGE48, 13, "MobileTech"


This is my DSDPlus.sites file:
; Copy and Paste this data into your DSDPlus.sites file
NEXEDGE48, 13, 12, "Tully"
NEXEDGE48, 13, 48, "Pulaski"


This is my DSDPlus.frequencies file:
;Site 012 for Tully NY
NEXEDGE48, 13, 12, 0, 150.9200, 0.0, 0
NEXEDGE48, 13, 12, 0, 153.1250, 0.0, 0
NEXEDGE48, 13, 12, 0, 153.5450, 0.0, 0
NEXEDGE48, 13, 12, 0, 153.6200, 0.0, 0

;Site 048 for Pulaski NY
NEXEDGE48, 13, 48, 0, 150.8675, 0.0, 0
NEXEDGE48, 13, 48, 0, 151.5500, 0.0, 0

 

[GTR8000]

I could be wrong, but since Mobiletech is a DFA (Direct Frequency Access) system, I don't believe you need to (or even should) put the frequencies in a file, even if you do use 0 as the LCN. Try wiping that out and see what happens. Of course I realize that doesn't explain why it follows voice traffic in two-dongle mode, but it's worth a shot.

 

[R0am3r]

It makes no difference if I have the frequencies in the DSDPlus.frequencies file. I deleted them (and saved the file), no change. I restarted DSDPlus, no change.

For giggles (and my sanity) I changed the frequency of the FMP24 to 151.010 (Oneida County P25 P2) and it worked perfectly. The interesting thing - when I switch to the P25 system, I can see FMP24 switch frequencies to the voice channel. But, when I put FMP24 back on the Tully Mobiletech freq (153.545), it never shows the frequency change on the FMP24 display. I see DSDPlus show the Group Call, but FMP24 stays parked on the NXDN control channel.

 

[GTR8000]

When DSD+ shows the group calls in the Channel Activity window, are the frequencies populating correctly?

Can you post some screenshots or a video when there is some activity? This is all very perplexing.

@k2hz Have you been able to track the Mobiletech system with DSD+ FL using a single dongle?

 

[cg]

I have a small NEXEDGE48 system I can monitor and it works fine with a single RTL-SDR.

chris

 

[k2hz]

When DSD+ shows the group calls in the Channel Activity window, are the frequencies populating correctly?

Can you post some screenshots or a video when there is some activity? This is all very perplexing.

@k2hz Have you been able to track the Mobiletech system with DSD+ FL using a single dongle?

I have not tried it due to my issues with dongles on VHF in my high RF environment. Since DSD+ can display channel activity and frequency I see no reason FMP24 could not track it.

 

[slicerwizard]

I could be wrong, but since Mobiletech is a DFA (Direct Frequency Access) system, I don't believe you need to (or even should) put the frequencies in a file, even if you do use 0 as the LCN. Try wiping that out and see what happens. Of course I realize that doesn't explain why it follows voice traffic in two-dongle mode, but it's worth a shot.

Site Loader doesn't work without channel data.

I have a small NEXEDGE48 system I can monitor and it works fine with a single RTL-SDR.

chris

But it's probably not a DFA system.

 

[R0am3r]

Site Loader doesn't work without channel data.


But it's probably not a DFA system.

Thanks for the generous responses.

slicerwizard - Your hint made me think of using a better tool to evaluate these Mobiletech sites. I ran LCN finder on my SDS200 and it confirms this site is indeed DFA. So I guess I have been wasting my time adding channels (and then replacing the channel numbers with zeros) to the DSDPlus.frequencies file?

Your suggestions did help me a bit, because I can eliminate something (I think). This is the Mobiletech Tully site:

 

[R0am3r]

I could be wrong, but since Mobiletech is a DFA (Direct Frequency Access) system, I don't believe you need to (or even should) put the frequencies in a file, even if you do use 0 as the LCN. Try wiping that out and see what happens. Of course I realize that doesn't explain why it follows voice traffic in two-dongle mode, but it's worth a shot.

GTR8000 - my apologies. I read your post and then spaced it. Sorry about that.

You are absolutely right about the DFA and it shouldn't matter if there are frequencies in the DSDPlus.frequencies file. Just to be sure, I removed the frequencies and everything else in the file. I also deleted everything in the following files: DSDPlus.groups, DSDPlus.networks, and DSDPlus.sites. The files are present, but zero bytes.

Guess what? It doesn't matter. DSDPlus does not track to the voice channels on a 1RTL setup.

 

[GTR8000]

I'm not really sure what to make of it. Perhaps 1R mode for NXDN48 is indeed broken. Send the author an email would be the next logical step.

 

[RaleighGuy]

I'm having an issue with a NXDN96 system, it is not playing audio or listing groups/Radios in the newest version. Also, though it lists the 3 correct channels it also lists several other channel numbers without frequencies, but this is only a 3 channel (6 with inputs) system. Yesterday 453.4125 was CC today it changed to 453.8125, but neither are listed as CC.

 

[mtindor]

I'm having an issue with a NXDN96 system, it is not playing audio or listing groups/Radios in the newest version. Also, though it lists the 3 correct channels it also lists several other channel numbers without frequencies, but this is only a 3 channel (6 with inputs) system. Yesterday 453.4125 was CC today it changed to 453.8125, but neither are listed as CC.

View attachment 86088

1. Do you have Control --> Combined CC/VC Monitor set ?
2. Do you have Output --> Synthesize All Digital Voice set ?
3. Do you have Output --> Speakers/Headphones set ?

FYI -- Although you have a signal, that's a pretty weak signal to say the least. If you looked at the command prompt window associated with DSDPlus, I'm betting it shows a lot of errors.

Press "d" while you have focus on the DSDPlus screen and let it start accumulating data from scratch on that site.

Mike

 

[RaleighGuy]

1. Do you have Control --> Combined CC/VC Monitor set ?
2. Do you have Output --> Synthesize All Digital Voice set ?
3. Do you have Output --> Speakers/Headphones set ?

FYI -- Although you have a signal, that's a pretty weak signal to say the least. If you looked at the command prompt window associated with DSDPlus, I'm betting it shows a lot of errors.

Press "d" while you have focus on the DSDPlus screen and let it start accumulating data from scratch on that site.

Mike

Yes, all three of those are set, yes I am seeing a lot of errors, yes it is a weak signal (it is low power and I'm near the limit of the system's reach). I'll try the d and see what happens. Thanks

 

[mtindor]

Yes, all three of those are set, yes I am seeing a lot of errors, yes it is a weak signal (it is low power and I'm near the limit of the system's reach). I'll try the d and see what happens. Thanks

Ok. Keep in mind that you should really expect very unreliable and unexpected results when monitoring such a weak signal. I'm sure somebody will debate this, but for any NXDN*/DMR/P25 signal you should be working with, at the very least, a 20db SNR. And even that won't guarnatee zero errors -- but should be sufficient. If you can't achieve a 20 dB SNR, you aren't going to have a good time.

Anyway - press "d" and let it accumulate info from scratch. But, before you do that, try to improve upon the signal to noise ratio as best you can.

Mike

 

[slicerwizard]

Yes, all three of those are set, yes I am seeing a lot of errors, yes it is a weak signal (it is low power and I'm near the limit of the system's reach).

You'll probably get considerably better decoding if you use the correct channel bandwidth.

 

[RaleighGuy]

@slicerwizard you are suggesting switch it to 12.5, thanks I'll try that.

Ok. Keep in mind that you should really expect very unreliable and unexpected results when monitoring such a weak signal.

@mtindor yes distance is my friend (or enemy in this case). Moving closer to the source made a huge difference and removed the multiple errors I see from home. Unfortunately this system is seldom used and in the 30 minutes I was there got no hits on it.

 

[R0am3r]

I'm not really sure what to make of it. Perhaps 1R mode for NXDN48 is indeed broken. Send the author an email would be the next logical step.

Check out DSDPlus v2.256. It fixes single receiver mode voice following of NEXEDGE DFA systems! I wasn't as crazy as I thought I was. Woot!

Thanks to the authors of DSDPlus Fastlane!!!