Scanning ATCO Gas NXDN96 system

[Mootly]

I hope someone can offer some assistance. I am still very much a newbie at this. I am attempting to scan the Alberta ATCO Gas NXDN96 VHF system that I can receive in my area on 153.62 but I never hear any audio. I have been monitoring intermittently for over 2 weeks and have seen ATCO Gas vehicles in the area doing their standard maintenance activities, so I am assuming there is actually some radio activity and it is just me that can't figure out how to hear it, but I could be wrong and they might not be talking.

Hardware is an RTL-SDR USB dongle with an outdoor 5/8 whip antenna, signal strength is good. Computer is an i5, CPU load is low. Audio output is to the headphone jack which is connected to an audio amplifier/external speakers. The system works fine for other FMP24 non-digital reception (eg: local weather broadcast) and also with FMP24/DSD+ decoding of a local DMR station.

Using 1R.bat as a reference, I created a batch file to launch DSDPlus (latest Fastlane) and FMP24:
start "" "DSDPlus.exe" -r1 -T -E -Pwav -o1 -i20001 >>1R-log.txt
start "" "FMP24.exe" -i"stx:1090:29" -rc -o20001 -P29 -f153.62

Frequencies as per radioreference in DSDPlus.frequencies:
NEXEDGE96, 200, 33, 1, 153.62, 153.62, 0
NEXEDGE96, 200, 33, 2, 154.31, 154.31, 0
NEXEDGE96, 200, 33, 3, 158.34, 158.34, 0

Everything appears to be working ok, except I never hear any audio and the DSD+ display shows a lot of data, almost all with some kind of ERR1, 3, 4, 6, 19, 22.
Signal strength is good, not overloading (I tried lower gains and it stops tracking below about 25). BW is set to 12.5 but it actually doesn't make a difference at any bandwidth, even down to 5.

Possible causes:
- frequencies in DSDPlus.frequencies are incorrect or incorrectly entered
- nobody is talking on the system
- some configuration error on my part

Following are copies of the DSD+ log and FMP24 startup and a screenshot.
I would really like to know if I am doing something wrong or if there is really no traffic on this repeater.
If more information is needed, let me know what (and how to obtain it).
Thanks in advance for any suggestions.


DSDPlus startup:

DSD+ 2.275
Current working directory is "C:\RadioApps\DSDPlus2p275FL-20001-109035"
Program role is single-receiver control/rest/traffic channel decoder
2021.01.19 9:49:57 Adding NAC/RAN/DCC/RAS data to event log file entries
2021.01.19 9:49:57 Writing synthesized audio to per-call wav files
2021.01.19 9:49:57 Appending synthesized audio to file '1R-DSDPlus.wav'

2021.01.19 9:49:57 Assuming FMPA/FMPP/FMP24 is signal source; auto polarity detect is disabled

2021.01.19 9:49:57 audio output device #1 = 'Headphones (High Definition Aud'
2021.01.19 9:49:57 audio output device #2 = 'Speakers (High Definition Audio'
2021.01.19 9:49:57 audio output device #3 = 'Line 1 (Virtual Audio Cable)'

2021.01.19 9:49:57 audio output device #1 (Headphones (High Definition Aud) initialized

2021.01.19 9:49:59 P25 data loaded; 0 networks, 0 sites, 0 channels
2021.01.19 9:49:59 3 frequency records loaded
2021.01.19 9:49:59 352 radio records loaded
2021.01.19 9:49:59 68 group records loaded
2021.01.19 9:49:59 0 site records loaded
2021.01.19 9:49:59 0 network records loaded
2021.01.19 9:49:59 0 site loader records loaded
2021.01.19 9:49:59 Fusion decoding enabled
2021.01.19 9:49:59 D-STAR decoding enabled
2021.01.19 9:49:59 NXDN4800 decoding enabled
2021.01.19 9:49:59 NXDN9600 decoding enabled
2021.01.19 9:49:59 DMR/MotoTRBO decoding enabled
2021.01.19 9:49:59 P25 Phase 1 and Phase 2 decoding enabled
2021.01.19 9:49:59 X2-TDMA decoding enabled
2021.01.19 9:49:59 ProVoice decoding enabled

Mono audio decoding initiated; press Esc to exit...
2021.01.19 9:49:59 Initiating FMPx link using link ID 20001...
2021.01.19 9:49:59 FMPx link error = -5
2021.01.19 9:49:59 [Server is not listening on selected link ID]


2021.01.19 9:50:04 Initiating FMPx link using link ID 20001...
2021.01.19 9:50:04 FMPx link established; link ID = 20001
2021.01.19 9:50:04 FMPx link established
2021.01.19 9:50:04 Sync:+NXDN96 TB CCDATA ERR2 SRV_INFO Category=Regional System=200 Site=33 MultiSite LocnReg GrpReg Auth CompCC Voice Data ShortData Status&RemCtl
2021.01.19 9:50:04 Sync:+NXDN96 TB CCDATA ERR30
2021.01.19 9:50:04 Sync:+NXDN96 TB CCDATA ERR4 SRV_INFO Category=Regional System=200 Site=33 MultiSite LocnReg GrpReg Auth CompCC Voice Data ShortData Status&RemCtl
2021.01.19 9:50:05 Sync:+NXDN96 TB CCDATA ERR8 SRV_INFO
2021.01.19 9:50:05 Sync:+NXDN96 TB CCDATA ERR6 SRV_INFO
2021.01.19 9:50:05 Sync:+NXDN96 TB CCDATA ERR12 SRV_INFO
2021.01.19 9:50:05 Sync:+NXDN96 TB CCDATA ERR10 SRV_INFO
..... etc ......

FMP Startup:

FMP24 2.70

Current working directory is "C:\RadioApps\DSDPlus2p275FL-20001-109035"
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 "C:\RadioApps\DSDPlus2p275FL-20001-109035"
Primary frequency list: '.\FreqList.csv'
Secondary frequency list: '.\FreqList2.csv'
Database search distance: 99.90 miles
Base latitude/longitude: 19.7163 -155.6241
Using RTL SDR device with serial number string 'stx:1090:29'
Using RTL SDR device #-1
Role is control/rest channel monitor;
Auto-starting control/rest channel following mode
Using DSD+ link ID 20001
PPM correction set to 35.0
Initial frequency set to 153.620000 MHz
Optimizing FFT calculations... done.

Audio output device #1 = 'Headphones (High Definition Aud'
Audio output device #2 = 'Speakers (High Definition Audio'
Audio output device #3 = 'Line 1 (Virtual Audio Cable)'

SDR device count = 6
SDR device #1 serial string = 'stx:1090:29'
SDR device #2 serial string = 'stx:1090:35'
SDR device #3 serial string = 'stx:978:30'
SDR device #4 is in use
SDR device #5 is in use
SDR device #6 serial string = 'DV3-00000001'
Found Rafael Micro R820T tuner
Found Rafael Micro R820T tuner
Tuner type=5 (R820T)
Serial string = 'stx:1090:29'
Sampling rate set to 2.400000 MHz
Frequency correction factor = +35.0 PPM
Waiting for DSD+ link with link ID 20001
No frequency data files found
Trunk control/rest channel following active
Accepted DSD+ link on link ID 20001

 

[racingfan360]

I'm sure someone will come back with a more complete answer but.....
1. It looks to be decoding ok albeit with a few errors
2. It's a NXDN9600 Trunk system with 153.6200 as the control channel, I think NXDN Type-C so with a dedicated control channel
3. But you're locked onto the control channel so you'll only ever get control data on it, no voice.
4. Try scanning the other frequencies not 153.6200 for voice.
5. If you ran a 2nd instance of DSD+ plus a 2nd dongle you'd see notification of voice calls on the control channel (but still only hear voice on a voice channel)

 

[racingfan360]

Trying to recall details on Type-C as it;s not my forte:
- Technically, it is possible on some Type-C systems to run voice on the control channel when the system loading needs it. I think that will be rare.
- Also on some Type-C systems it is possible that the the control channel will move overnight to a different channel/frequency. So while you have only one dongle/DSD+ instance running then the advice is scan only those channels that DON'T have the Control Channel data running on it. While your scan list contains the active CC channel it will always get stuck on it, never get to scan the voice channels.

 

[Kazzaw]

Signal is a little low, hence the ERRs in decoding.

It looks as though there is traffic on the system, however you will need to manually ID the channel numbers to the frequencies. Usually the best way to do this is to look up the frequencies in the regulatory bodys search engine on the specific site, and then when you see a voice call jump between those frequencies and find a channel that's active

 

[Mootly]

Trying to recall details on Type-C as it;s not my forte:
- Technically, it is possible on some Type-C systems to run voice on the control channel when the system loading needs it. I think that will be rare.
- Also on some Type-C systems it is possible that the the control channel will move overnight to a different channel/frequency. So while you have only one dongle/DSD+ instance running then the advice is scan only those channels that DON'T have the Control Channel data running on it. While your scan list contains the active CC channel it will always get stuck on it, never get to scan the voice channels.

Thanks, I really appreciate the feedback. I have deleted the cc from the frequency list in DSDPlus.frequencies. Probably have to wait until tomorrow to see if anything changes. I will also use SDR# to monitor the non cc channels to see if there is ever any voice traffic (great idea, should have thought of that).
As soon as I can figure out how, I will try a second DSD+ instance and a second dongle. It took me several hours to get this far!

 

[Mootly]

Signal is a little low, hence the ERRs in decoding.

It looks as though there is traffic on the system, however you will need to manually ID the channel numbers to the frequencies. Usually the best way to do this is to look up the frequencies in the regulatory bodys search engine on the specific site, and then when you see a voice call jump between those frequencies and find a channel that's active

Thanks for the feedback, it is really appreciated.
I tried using a different dongle but the signal level isn't going to get any better. I am stuck in a controlled housing area and don't have the freedom to put up even a small mast.
I found the non-cc frequencies from the radioreference database, but I suppose there is no guarantee the database is accurate. I can access the government license database so I will try to go through it and see if I can find other frequencies at the cc location. Its a slow process but it might work.

 

[slicerwizard]

Hardware is an RTL-SDR USB dongle with an outdoor 5/8 whip antenna, signal strength is good.

Signal strength is not good enough. Sounds like you can't fix that.

And there is no voice traffic. You can't fix that either.

3. But you're locked onto the control channel so you'll only ever get control data on it, no voice.
5. If you ran a 2nd instance of DSD+ plus a 2nd dongle you'd see notification of voice calls on the control channel (but still only hear voice on a voice channel)

He's using DSD+'s 1R mode, as he should be, so he'll hear any voice traffic that comes along.

- Also on some Type-C systems it is possible that the the control channel will move overnight to a different channel/frequency. So while you have only one dongle/DSD+ instance running then the advice is scan only those channels that DON'T have the Control Channel data running on it. While your scan list contains the active CC channel it will always get stuck on it, never get to scan the voice channels.

He doesn't need a scan list. He just needs to tune to the current control channel, which he is doing.

It looks as though there is traffic on the system, however you will need to manually ID the channel numbers to the frequencies. Usually the best way to do this is to look up the frequencies in the regulatory bodys search engine on the specific site, and then when you see a voice call jump between those frequencies and find a channel that's active

There is no voice traffic and he already has the channel number to frequency mapping.

 

[Mootly]

Signal strength is not good enough. Sounds like you can't fix that.

And there is no voice traffic. You can't fix that either.


He's using DSD+'s 1R mode, as he should be, so he'll hear any voice traffic that comes along.


He doesn't need a scan list. He just needs to tune to the current control channel, which he is doing.


There is no voice traffic and he already has the channel number to frequency mapping.

Thanks, slicerwizard. I can improve the signal strength a bit using a cable distribution amp, but as you say, there doesn't appear to be any voice traffic. How would I know if there ever was a voice channel assignment? I have the ">>1R-log.txt" parameter included but there is nothing in the log. Would there be an entry if a vc was ever assigned?
As an addendum, I looked through all the license records for this client and determined the set of frequencies assigned to each location (they are largely duplicated). I then took the site closest to me (about 25 km) and set up a scan list and monitored the frequencies (excluding the CC) for several days. I never heard anything, ever. I'll keep digging, but I suspect the company has moved to some other form of communications.
I really appreciate the help from you and the others. This is all new to me and I am struggling to understand and make things work and it is nice to have the feedback.

 

[slicerwizard]

How would I know if there ever was a voice channel assignment?

a) You'd see the voice channels in the channel window

b) You'd find voice call entries in the 1R-DSDPlus.event file

 

[Mootly]

a) You'd see the voice channels in the channel window

b) You'd find voice call entries in the 1R-DSDPlus.event file

Again, thanks.
Using what I learned from all the above, I started scanning a different NXDN96 system, this one apparently registered to Whyte Comms in Edmonton. The CC and one of the voice channels fit the standard calculation:
Channel Frequency Calculation
397 454.95 ((454.95-450.00)/.0125)+1=397 CC
365 454.55 ((454.55-450.00)/.0125)+1=365
But the channel 180 does not fit the calculation at all:
180 461.1125 ((461.1125-458.875)/.0125)+1=180

I was able to find channel 180 through a combination of watching the frequencies licensed to Whyte Comms in SDR+ and substituting them in to the DSDPlus.Frequencies file until I found a match. I suppose there is no reason, it is just the frequency that they stuck into the controller table.
The signal strength is similar to the previously reported ATCO system and I get similar errors showing in the DSDPlus screen, but the voice decoding is consistently very good, so obviously the errors aren't affecting the reception.
A big thanks to the person(s) who developed the 1R configuration, it works great!

 

[slicerwizard]

Doesn't seem that odd for the 450-455 and 460-465 ranges to use different base frequencies.

 

[Mootly]

Finally, an update to the ATCO Gas NXDN96 system. The DSDPlus.frequencies file that I first listed in this thread was ok except for the channel numbers. Here is the correct listing which is confirmed working:

NEXEDGE96, 200, 33, 27, 153.620, 153.620, 0 ;ATCO Sherwood Park
NEXEDGE96, 200, 33, 28, 154.310, 154.310, 0 ;ATCO Sherwood Park
NEXEDGE96, 200, 33, 29, 158.340, 158.340, 0 ;ATCO Sherwood Park

As I have learned, the secret is to examine the DSDPlus.event file to find the channel numbers that it is trying to use. Then assign the frequencies listed in the radioreference database to the channels (or if not listed, monitor the licensed frequencies for that system as per TAFL and/or work out the frequencies from the base/offset calculations, if you can determine a workable base and step size).

Once again, thanks to the community for your help.

 

[Kazzaw]

Good to hear. Hard work sometimes, especially on quiet systems, but pays off when you get it all sorted