2+ RTL P25 TDMA Solution?

[AggieCon]

Does anyone know of a work around for OP25 or another program that allows one to decode a trunked P25 Phase 2 system (or systems) with multiple RTLs?

The LSM decode on OP25 is superior; however, I don't have a single receiver that will cover a wide enough bandwidth to encompass the systems I follow.

It is my preference to record all traffic on the system.

 

[natedawg1604]

Does anyone know of a work around for OP25 or another program that allows one to decode a trunked P25 Phase 2 system (or systems) with multiple RTLs?

The LSM decode on OP25 is superior; however, I don't have a single receiver that will cover a wide enough bandwidth to encompass the systems I follow.

It is my preference to record all traffic on the system.

You only need one dongle to monitor a system, just don't specify a center frequency in the .TSV file. As to the recording aspect, try this out.

 

[AggieCon]

I want to monitor all of the voice channels at the same time. I want to record all of the traffic on the system.

Edit: I've looked into his trunking recorder before. How is it an advantage over running OP25 with the -L attribute?

 

[AggieCon]

Nate,

Thanks for pointing me to Trunk Recorder. I am glad I revisited it. It's a step closer to what I am looking for, and I think it will be feasible to expand it to what I need (record all traffic on multiple systems).

I'm having some problems getting it to decode... but hopefully I'll get it figured out over the weekend.

I would love to talk to anyone who is willing to teach me the technical side of the SDR software and decoding.

 

[natedawg1604]

Nate,

Thanks for pointing me to Trunk Recorder. I am glad I revisited it. It's a step closer to what I am looking for, and I think it will be feasible to expand it to what I need (record all traffic on multiple systems).

I'm having some problems getting it to decode... but hopefully I'll get it figured out over the weekend.

I would love to talk to anyone who is willing to teach me the technical side of the SDR software and decoding.

Wonderful, glad you're making progress. So, what type of computer do you have? (particularly Memory & CPU capacity)? How much CPU% is used while running OP-25?

OP25 is among the most difficult SDR program to install, it is not for the faint of heart. (But it sounds like you're up to it). However, it's amazing once it's working, especially for simulcast, and it's the ONLY option for Phase II. Please note, there is a semi-official OP-25 thread here, several OP-25 experts monitor it regularly, including (I think?) the author of Trunk Recorder. AFAIK, I'm 99.8% sure it's impossible to run multiple dongles on OP-25.

OP-25 does support Ettus USRP's and the HackRF, which would allow you to use much more spectrum at once (provided your CPU was up to the task!), but of course, they cost a great deal more.

 

[AggieCon]

I read the entire thread (it took awhile) you linked to before making this new thread. Some good info in there. I should have copied out the important info to make a summary post.

I run i&-3770K 3.5 gHz, 32 gb RAM, and an Intel SSD (along with a number of HDD). I'm using VMWare player. I gave it 8gb RAM and 2 cores. It uses most of that processing power; however, it seems to handle the load fine. If I add more receivers, I might give it another core or two.

I was amazed when I flipped the switch on OP25. The decode quality is great. Right now, I'm trying to figure out the best approach to create exactly what I need.

I think the RTL approach is best, especially if it's going to have mainstream utilization.

Luke, the author of Trunk Recorder, claims OP25 has a bad memory leak or process demand (or something along those lines) that he claims to have fixed in his software. So once I get it to work, hopefully my processing demands will decrease.

 

[rylvir]

If you do get Trunking Recorder up and running, please share your experience!

Here is a link to the performance modification to OP25 Luke posted online. I rebuilt my working OP25 install with this code change and the CPU use was drastically improved, but the audio stuttered terribly and was not readable.

QPSK in OP25 & Fixing Performance – Luke Berndt

 

[AggieCon]

I rebuilt my working OP25 install with this code change and the CPU use was drastically improved, but the audio stuttered terribly and was not readable.

Did you disable pulse audio? PulseAudio/HOW-TO: Disable PulseAudio and use ALSA (without removing PulseAudio) for Ubuntu - Kodi

 

[PiccoIntegra]

You don't need to disable Pulse audio. The fix is simple;

create this file if it does not exist, otherwise edit the file:
~/.gnuradio/config.conf

Add this section to the file:

[audio_alsa]
period_time = 0.100
nperiods = 5