Unitrunker Question and OP25 Setup Questions

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KC2KQH

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Hi All,

I've spent the last 8+ hours struggling to get OP25 up and running. I finally worked out the issues that were preventing my USB SDR stick from working. I've got OP25 to the point where I can see signals on the scope, but I still can't seem to get any decode of voice or control channel data.

I haven't been able to find the NAC for the system I'm trying to monitor, and I was figuring that may be my problem when it comes to voice decode. I setup my system in the trunk.tsv file, and tried to make use of NAC 0xF7E. My understanding is that F7E is somewhat of a wildcard NAC that will unmute all receivers, though I'm guessing OP25 isn't designed to do so. When calling the trunk.tsv file, I don't see any talkgroups pop up in the space above the frequency on the first tab. I'm thinking with the wrong NAC, any traffic is being ignored, hence not seeing talkgroups here. It's a VERY busy system, so if things were working, I'd expect to see something here in under a minute. From reading online (I think it was another post here, but can't remember at this point) I believe that simply opening and parking OP25 on the control channel without calling trunk.tsv should result in system information, including the NAC appearing in the Traffic tab. This tab remains blank in my case, unless I call trunk.tsv, in which case it populates the info from the file, and anything else remains as zeros. I have verified with my scanner and Unitrunker that I am on the correct control channel frequency, and that what I pulled from memory hadn't changed.

So, at this point, I feel I'm doing something wrong, I'm just not sure what. Every other problem I've managed to sort out with enough head-banging, but I've been stuck here now for a few hours.

My Unitrunker question is this...I understand Unitrunker used to come with kNACk, to decode NACs. I've seen it in my Unitrunker folder in the past. Upon reinstalling Unitrunker today for this project, I no longer see kNACk. I attempted the next version back, with the same result. I may have an older version which had it hiding on the network somewhere, but I'm not sure. Is kNACk no longer offered/supported? I thought maybe the feature was rolled into Unitrunker, but I can't seem to find it in any of the screens.

The signals are strong on the scope, as expected. I'm using an 800 rubber duck on about 3" worth of feedline, and can normally tell the control channel is there without an antenna connected. I pulled my SDR ppm correction value out of SDR#, so I'm sure that's correct.

For reference, the two lines I'm starting scope.py with look like:

python scope.py --args rtl=0 -N LNA:46 -f 853.2125 -S 2048000 -q 51 -V -T trunk.tsv

or

python scope.py --args rtl=0 -N LNA:46 -f 853.2125 -S 2048000 -q 51 -V

Any help is greatly appreciated. I'm a computer geek/tech, but it's been a long time since I've been into Linux, so that part has been a bit rough.

-Ryan
 

KC2KQH

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Edit to add:

Upon doing some more digging, I turned up with the NAC for the system I'm working with. That doesn't negate my questions as far as decoding the NAC myself though.

Also, I've noticed when I go back into the terminal window while scope.py is running, I'm seeing process_data_unit timeout. This is repeating itself quite frequently, with messages relating to the control channel having been set to the frequency I've set in trunk.tsv. I can't imagine this is starved for resources. It's running inside VMWare Workstation, and I've allocated it 2 CPU cores at 3.8 GHZ each from my i5-3570k, along with 8GB of RAM. I could push those a little higher still. I'll be able to do much better hardware-wise when my ESXi server board comes back from RMA.
 

SCPD

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The program displays the NAC for the control channel on the Properties tab of the site window.
 

KC2KQH

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Thank you for that. I poked around earlier today but didn't run across it on my own.

-Ryan
 

br0adband

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One might think if the system you're trying to monitor is that used it would have a listing here at RR with the NAC as well, you didn't say exactly what system you're attempting to monitor nor where you're located so, without that info there's not much else to be offered on that. Also, if you have a scanner that should show you the NAC of the control channel as well unless it's not a digital capable one for P25 Phase I and II support. As mentioned above, Unitrunker should easily display the NAC without much effort at all; you can also use DSD+ to show the NAC pretty easily.

Of course you said you finally discovered the NAC so that's all a wash now anyway. :)

The process_data_unit timeout notice is perfectly normal, really, and it's been discussed many times in the "main" OP25 discussion thread which is probably where you should have made your post but it's really not a problem, believe it or not - also it means you're not far off the mark because if you were you'd be getting sync errors which means you're off-frequency enough for it to not get a lock on the signal so if you're not seeing sync issues you're close:

https://forums.radioreference.com/s...-virtualbox-project-run-op25-windows-7-a.html

I do get that the intention is to get the voice decoding going and you should have an easier time of things now that you've got the NAC - without that you're not going to have much use for OP25. The main trunk.tsv file defines the parameters of the system(s) you wish to monitor with OP25 and without it you're not going to get much done either - I'm not sure what you mean by "decoding the NAC" since it's just the necessary ID and is always broadcast and listened for by the units on the system itself.

I don't believe that OP25 can be used in a 'wide open" mode where it'll just decode whatever any control channel it happens to be tuned to hence the trunk.tsv file (you can change that filename of course to anything you want) but it's a necessity to get OP25 working properly. If I'm incorrect on that I apologize, but in my use of OP25 I've never tried to use it without one because the instructions and guides always make it rather clear that the config file aka trunk.tsv is a requirement so the software knows what the hell it's supposed to be looking for to work with.

Tips: leave the virtual machine to use only the physical cores on the computer's CPU - if it's a dual core with hyperthreading, tell the VM it has access to 1 processor with 2 cores, if it's a quad then it's 1 processor 4 cores, etc. Don't use hyperthreads for the VM as it can cause even more severe timing issues with OP25 for audio decoding purposes.

There was a tweak related to disabling Pulse Audio which finally made OP25 workable in a VM; previously before that tweak was discovered the audio was always choppy and unreadable and it didn't really matter what CPU/RAM or how many cores you dedicated to the VM, it just wouldn't produce readable audio from the decoding process, period. If you haven't used that tweak then I suggest you do and you can find out how to do it here (they happen at about the 9 minutes 48 seconds where the author of the video begins the explanation for the "fix" if you can't find it specifically):

https://www.youtube.com/watch?v=s2iJMtPJu-I

And hopefully you followed the "new improved method" for installing OP25 which is much easier and much faster than the old compile-it-yourself method from long ago which had a lot more involved in getting things functional:

https://forums.radioreference.com/s...ject-run-op25-windows-7-a-16.html#post2654021

I've used those steps that Dark-Sky put together oh, maybe 25 times so far for myself in VMs and for other people as well and haven't had a single instance where I had any issues worth even noting - in VMs after disabling Pulse audio everything was great and up and running in short order.

Worse comes to worse and you get nowhere, scrap the VM and start over clean and fresh using Dark-Sky's instructions (I'm pretty sure you probably use those but I won't bet on it) and then disable Pulse audio per the video instructions, create a proper trunk.tsv for the system you want to monitor with the correct and verified parameters (remember the tsv files are tab-delimited files and should never ever have any spaces in them) and see what happens.

Good luck...
 

boatbod

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If you take the "-T trunk.tsv" out of the command line options, scope.py will run in non-trunking mode and report the NAC of any control channel you tune to.

Decoding audio takes careful tuning. Use the ppm and fine tune adjustment to accurately center the control channel, then switch to the screen showing the 4 levels and tweak it again to make the levels equally spaced above and below the midline.

Decoding phase 2 audio requires both -T and -2 options on the command line.

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KC2KQH

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@boatbod,

My understanding from having read somewhere yesterday was that removing the -T and the filename would result in decoding the control channel I parked on, as you stated. This isn't happening for me. I get a blank Traffic tab when I attempt to do this. I've also been unsuccessful in decoding a single voice channel when I park OP25 on it and wait for activity. I haven't attempted to disable pulse audio as suggested yet. Hopefully I'll get some time to try that today.

Thanks for the info,
-Ryan
 

KC2KQH

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@br0band,

I apologize for not including the specifics on the system in my original post.
https://www.radioreference.com/apps/db/?sid=411

There is no NAC listed in the DB for it, nor for the other system I checked when I couldn't find one for this one. I wound up finding the NAC in the wiki after some more searching. This system isn't my primary goal, but the one I'm after is really weak here, and I haven't made some necessary antenna system improvements for that purpose just yet. Ultimately, I'm after a Phase 2 TDMA system. I landed on this one for now as I'm very familiar with the system (it's used by my old agency) and I'm only maybe 5 miles from one of the sites, so it's strong here. As far as a digital scanner giving me the NAC, I couldn't figure out how to see it on my BCD396xt. I've run DSD before, but didn't feel like getting all of that running again just to pull a NAC.

Would I be correct to assume that the timeouts I'm seeing are just due to the amount of raw data coming in? Perhaps there isn't any down sampling implemented with this setup, and there just isn't enough processor time available to decode all of it? In scrolling through the terminal, I haven't seen any sync errors.

As far as requiring the trunk.tsv, my understanding was that I should at least be able to display the control channel info simply by parking on that frequency, and boatbod's reply above would seem to indicate the same. As I already stated in my reply above, that isn't happening for me.

I haven't been making use of any hyperthreading with the VM. That gets to be a gray area, where some applications see performance improvements, while others wind up suffering from having it enabled when it comes to virtualization. That said, I just leave it out of my virtualization to avoid problems.

I hadn't seen anything relating to disabling pulse audio until you mentioned it. I'll take a look at this later today. Given that I'm getting absolutely nothing at this point, I'm not sure that will completely resolve my problems, though it sounds like I'd have come to that problem at some point anyway, so thank you for bringing that up.

The instructions I used were from here:
InstallInstructionsPage

...and I used the newer method at the top, not the old method. I had tried to get this going some time back with the old method, but never had time to finish the setup. I may very well just spin up another VM and give the instructions you provided a try. That's the beauty of VMs and so many hard drives at my disposal, I can just about endlessly fire up more VMs as I need.

I really appreciate the detailed reply. I'll go through all of this information at some point today and let everyone know how I make out.

-Ryan
 

KA1RBI

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I get a blank Traffic tab when I attempt to do this.
OK the blank traffic tab suggests you haven't gotten a successful control channel decode. Removing the trunking conf file (-T) thus running in manual mode is a good first step in finding out what's going on. If you could please post screen prints of the various tabs (other than the Traffic tab), esp. the spectrum, c4fm, datascope and constellation tabs... Some possible causes of the problem are incorrect PPM (-q) setting and failure to add a tuning offset (try adding -o 50000) to work around the DC offset...

Max
 

KC2KQH

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I was just working on a reply when slicer added one. So despite P25 digital voice being used exclusively on the system, OP25 won't work on this system? That would seem to go along with my findings, which I'll spell out below.

With adding the -o 500000 suggested by Max, I was able to start getting decode when parked on a single voice channel I chose out of the system slicer just mentioned. After that, I decided to try my luck on a newer system, which is using TDMA on at least some talkgroups. With that system, I get control channel decode, as well as all of the voice channels. Everything is working fine there.

That system is:
https://www.radioreference.com/apps/db/?sid=7021

So if I were to make a guess at this point...
Would it be safe to say that OP25 understands APCO 9600 control channels, but not Motorola control channels?

Greatly appreciate everyone's help here thus far.
-Ryan
 

boatbod

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So if I were to make a guess at this point...
Would it be safe to say that OP25 understands APCO 9600 control channels, but not Motorola control channels?

Greatly appreciate everyone's help here thus far.
-Ryan
Correct, its P25 only and does not do Motorola
 

KC2KQH

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Well that explains my troubles. In that case, it appears I'm up and running, thanks to some of the tips here. Now to get my antenna situation worked out.

Thanks again everyone!
-Ryan
 

br0adband

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OP25 is named as such since it's only useful for decoding P25 Phase I and Phase II comms (I believe the O stands for the project leader's name long ago, Michael Ossmann) - in fact it's the only software based solution for computers that I'm aware of, been that way forever so far and who knows if another solution will ever present itself. I and many others keep hoping that DSD+ will add Phase II support someday but until that actually happens OP25 does a really great job of it.

Glad you got something happening. I did find it odd that the main system you wanted to monitor does claim it has P25 support and was originally supposed to move to that standard from conventional analog a long time ago (based on available info) but apparently still doesn't fully utilize it for the whole system.
 

scaseyjordan

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What git source repo are you guys using to insta OP25? The Osmocom.org/op25 doesnt seem to exist when I reference it. Thanks.

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br0adband

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If the OP25 Osmocom Git isn't working I'd suggest trying it again at a later time, that particular one tends to be up and down in terms of availability with an all-too frequent basis. It works one day, not the next, works the next, it's down for days, then it's back up, etc so check it again in 24 hours or so and see what happens I suppose.
 
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