OP25 multiple systems?

[kc2klc]

I have successfully been monitoring the local (Broome County, NY) APCO-P25 Phase II system using Boatbod OP25 with an RTL-SDR V3 blog connected to a Raspberry Pi 4B. My trunk.tsv is:
"Sysname" "Control Channel List" "Offset" "NAC" "Modulation" "TGID Tags File" "Whitelist" "Blacklist" "Center Frequency"
"Broome" "453.8375" "0" "0x2a8" "cqpsk" "broome.tsv"
And the command line I use is:
./rx.py --args 'rtl' -N 'lna:35' -S 2500000 -O pulse -T trunk.tsv -v 5 -V -2 -U 2> stderr.2
There is a broome.tsv file that contains the talkgroup IDs.

I now want the ability to monitor NYSEG (the installation came with a nyseg.tsv that apparently has the right control groups listed). Using SDR++, I see a nice strong signal on their control frequency (152.0825). I edited the trunk.tsv as follows:
"nyseg" "152.0825" "0" "0x2a8" "cqpsk" "nyseg.tsv"
And used the same command line, only substituting "-w" for the "-V". However, the tsbks counter is not incrementing - so it doesn't appear to be working.

Any idea where I went wrong? And how I can easily switch between Broome & NYSEG (short of writing a shell script to modify trunk.tsv every time I want to switch)? Thanks!

 

[maus92]

"0x2a8" refers to the NAC specifically for the Broome County West Simulcast site of the CNYICC. You need to replace this value with the NAC for the Binghamton site of NYSEG, which the RRDB shows as 260 or "0x260".

 

[kc2klc]

Bingo! tsbks is now incrementing. Been monitoring for a little while, and not hearing any voice traffic, which seems unusual given the major snowstorm going on - I'll listen a little longer and see if I hear anything.

So now - I have two separate shell scripts on my desktop with the appropriate command lines for either Broome or NYSEG - but it seems OP25 defaults to using trunk.tsv - is there a command line option to use an alternate file, or must I have two different files that I rename to trunk.tsv depending on whether I want to listen to Broome or NYSEG?

 

[maus92]

You can use any .tsv filename you like instead of trunk.tsv as long as that file contains the appropriate configuration data. You would need to modify the command line to replace "trunk.tsv" with whatever "xxx.tsv" you create. Or you can enter the configuration data for both system / sites on separate lines (rows) of the trunk.tsv file. This config would scan both systems / sites sequentially. I've never done this - I've heard that it takes a few seconds to switch between systems / sites.

 

[kc2klc]

Silly me - didn't even notice that "trunk.tsv" was in the command line! That makes total sense - thanks for the quick responses

Final (I hope) question - I'm only hearing very brief broken snippets of voice (when I monitor the Broome system I get nice clear voice). The control frequency definitely has a very clear signal on it. Any idea how I might troubleshoot this?

 

[kc2klc]

Silly me - didn't even notice that "trunk.tsv" was in the command line! That makes total sense - thanks for the quick responses

Final (I hope) question - I'm only hearing very brief broken snippets of voice (when I monitor the Broome system I get nice clear voice). The control frequency definitely has a very clear signal on it. Any idea how I might troubleshoot this?

Never mind - just re-started OP25 and now I'm getting beautiful voice decodes. This may be very helpful when we get our next blackout (they happen frequently here in the hills) and I can monitor NYSEG using battery power. Thanks again!

 

[wgbecks]

Your SDR likely needs frequency compensation assuming it's getting an adequate signal level. I would reduce the sample rate to -S 1000000 and then post your FFT, Constellation, and Mixer plots for the system your having difficulties with that we can further assist.

 

[kc2klc]

My problem appears to be resolved, but thanks so much for the offer of assistance. I'm a bit of a n00b so I'm not very familiar with those tools, but I'll keep them in mind if I require future troubleshooting.

 

[boatbod]

Your SDR likely needs frequency compensation assuming it's getting an adequate signal level. I would reduce the sample rate to -S 1000000 and then post your FFT, Constellation, and Mixer plots for the system your having difficulties with that we can further assist.

I concur with the recommendation to reduce the sample rate to "-S 1000000". Unless there is a dc spike or a non-tcxo dongle, op25 boatbod generally does a pretty good job of auto-compensating for ppm errors without having to tell it anything about that these days.

 

[kc2klc]

Will do. Pretty sure my RTL-SDR V3 blog has a TCXO.