[op25-dev] OP25 setup once built [7 Attachments]

John Ackermann N8UR jra@febo.com [op25-dev] op25-dev at yahoogroups.com
Fri Jun 9 14:57:14 UTC 2017

Thanks for the quick replies.  Attached are:

1.  trunk.tsv and the local talkgroup list montgomery.tsv

2.  Screenshot of the console after starting, using -v 255.

3.  Screenshots of spectrum, datascope, constellation, and traffic.

Here is the command line I'm using:
./scope.py --args 'rtl' -f 853.5e6 -N 'LNA:35' -o 17e3 -V -v 255 -S 
2480000 -q 0 -T trunk.tsv

My RTL-SDR.com dongle seems to be just about on frequency; it has a 
TCXO.  I've messed with PPM correction as well as fine tuning and, 
though I'm not sure just what I should be looking for, changing those in 
either direction tends to result in tuning error messages.

I am not sure if Montgomery County is C4FM or CQPSK.  Radio Reference 
seems to indicate C4FM; I've mainly used that, but tried CQPSK a couple 
of times with no "traffic" shown in either case.


On 06/09/2017 09:44 AM, 'wa8wg' wa8wg at centurytel.net [op25-dev] wrote:
> John,
> You should normally get an error message when starting scope.py if your 
> trunk.tsv if your trunking system occupies more bandwidth than is 
> supported by the sample rate capability of your SDR.  Maybe you could 
> post your trunk.tsv for a look see?   However, it sounds like your 
> constellation doesn’t look the best.   Is scope showing the P25 frames 
> being decoded and does it indicate any errors on those frames?  I have 
> my op25/GNU Radio running on Ubuntu 14.04 virtualized in Oracle 
> VIrtualBox on my Windows 10 laptop.
> Bill, WA8WG
> William G. Becks, WA8WG
> N7027 Shady Lane Circle
> Porterfield, WI 54159
> Telephone: 715.735.0131
> E-Mail: wa8wg at centurytel.net <mailto:wa8wg at centurytel.net>
> *From:*op25-dev at yahoogroups.com [mailto:op25-dev at yahoogroups.com]
> *Sent:* Friday, June 9, 2017 7:28 AM
> *To:* op25-dev at yahoogroups.com
> *Subject:* [op25-dev] OP25 setup once built
> Hi --
> After looking at the archives, I think I may need to use a different 
> software branch, but here's where I stand:
> 1.  Downloaded OP25 from the oscomcom site.
> 2.  Built without any problems on Mint 17.04 with Gnuradio 3.7.11.  
> Computer is an i7 laptop with 8GB RAM.  I'm using an RTL-SDR dongle for 
> now; I can try a USRP but wanted to start with the simpler hardware.
> 3.  Cobbled up .tsv files for local P25 system (Ohio MARCS-IP, 
> Montgomery County site, C4FM).  This site has 30 channels and the 2.4 
> msps rate of the dongle can't catch them all, but I am covering the 
> control channel pllus several more channels.
> 4.  Scope.py seems to run fine with all windows looking proper.  
> Selecting some tabs causes timeout errors on the console, but those stop 
> when I switch tabs..
> 5.  I seem to be tuned to the control channel (853.600) and see a 
> not-terrible constellation.
> 6.  But I don't see any traffic decoding, much less get any audio (I 
> know that the 30 channels at this site are spread over a bandwidth 
> greater than the RTL-SDR dongle can provide; I can bring a USRP to the 
> game but for now would be happy just to decode control data.
> I'd appreciate any help, particularly on what the scope.py command line 
> should look like.  And should I be using a version other than what is on 
> the Osmocom site?
> Thanks much,
> John Ackermann   N8UR
> jra at febo.com <mailto:jra at febo.com>
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