op25-dev

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309 discussions

P25 symbol timing recovery: tone detection method
by ikj1234i 28 May '12

28 May '12

P25 signals modulated using the CQPSK format throw off a loud tone at 4,800 Hz, as shown by a plot of the power spectrum of the signal's magnitude. C4FM-modulated P25 signals do not appear to possess this interesting property. The file in samples 'prwn-d256.dat' appears to be a CQPSK signal with distinctive LSM characteristics. I've uploaded a simple python app which can be used to plot a complex capture sample file - magsq-psd.py. The one non-obvious arg (--calibration) must be used if/as necessary to bring the signal to near zero IF. Note that hardware FM discriminator-tapped receivers cannot be used here since a copy of the signal prior to demodulation is required. A receiver software implementation using the tone detection method can be done using a low-complexity setup such as a DSP CIC filter. Another nice thing is that a tone detection loop works well even when there is some frequency mismatch... Max

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OP25 GRC - Almost but not quite working
by Andy Knitt 21 May '12

21 May '12

I have the OP25 GRC demo that Balint provided up and running. Everything seems to working except I'm not getting any audio out of the OP25 block. I'm getting the "four line" output from the dibit output port when there is traffic on the channel, and the autotune output is outputting data. However, no audio. I put a scope on the audio output and it's a flat line at zero, even when the dibit output is "four lines". Any tips on how to further troubleshoot? Thanks, Andy

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IRC Channel
by Steve Glass 19 May '12

19 May '12

Its been suggested that we start a channel on IRC so we can discuss OP25 and Osmocom stuff. Anybody here an IRC guru? Do we want a channel just for OP25 (which may not have many people in it) or perhaps take part in a potentially larger Osmocom one? What do people think?

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GRC blocks for OP25 and 4FSK missing
by mungewell 15 May '12

15 May '12

Hi all, Just getting started with GnuRadio and RTL2832 so might be missing some details, by following the instructions here: http://op25.osmocom.org/wiki/wiki/BuildInstructionsPage I was able (with a couple of hacks) to built OP25, IMBE and 4FSK - however these did not appear as selectable blocks in GRC. After some time I was able to figure out that they are missing 'xml' definitions in '/usr/local/share/gnuradio/blocks'. Creating a quick/fake '4fsk.xml' made it/something appear. So should these exist? Does anyone have examples of what they should be....? BTW the OP25 which did appear, seems to be from Baz install, not the above instructions. I also experienced problems with build against latest GnuRadio git (seems that 'gruel_common.i' has moved) and the include files are not being installed... other than that things are 'peachy' :-) -- libtool: compile: g++ -DHAVE_CONFIG_H -I. -I../.. -I/usr/local/include/gnuradio -I/usr/local/include -I/usr/include/python2.7 -I ../../../imbe_vocoder/src/lib -g -O2 -Wall -Woverloaded-virtual -pthread -MT _repeater_la-repeater.lo -MD -MP -MF .deps/_repeater_la-repeater.Tpo -c repeater.cc -fPIC -DPIC -o .libs/_repeater_la-repeater.o In file included from repeater.cc:3862:0: rs.h:8:29: fatal error: op25_imbe_frame.h: No such file or directory compilation terminated. make[4]: *** [_repeater_la-repeater.lo] Error 1 make[4]: Leaving directory `/home/simon/op25/repeater/src/lib' make[3]: *** [all] Error 2 make[3]: Leaving directory `/home/simon/op25/repeater/src/lib' make[2]: *** [all-recursive] Error 1 make[2]: Leaving directory `/home/simon/op25/repeater/src' make[1]: *** [all-recursive] Error 1 make[1]: Leaving directory `/home/simon/op25/repeater' make: *** [all] Error 2 simon@drifter:~/op25/repeater$ find .. -name 'op25_imbe_frame.h' ../blocks/src/lib/op25_imbe_frame.h simon@drifter:~/op25/repeater$ find /usr/local/include/ -name 'op25_imbe_frame.h' simon@drifter:~/op25/repeater$ -- Simon

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Building under Ubuntu 12.04 - blocks gives error "op25.cc:3115:13: error: 'ptrdiff_t' does not name a type"
by Richard Clarke 10 May '12

10 May '12

OK I've just upgraded my Ubuntu box to 12.04, from 11.04 (couldn't help myself). I'm trying to rebuild op25 but I'm getting the following error, followed by a string of relate ones (I'm guessing) Compiling blocks: op25.cc:3115:13: error: 'ptrdiff_t' does not name a type A Google search for this kind of error seems to be pointing to stricter typedef requirements by gcc 4.6 with the solution being to include an additional system header file cstddef. However I'm not sure where to include this in the op25 source. I tried putting it in the op25.i swig interface file so that it ends up in the generated op25.cc file however that doesn't appear to have worked. Anyone already solved this or can provide some guidance? Ubuntu 12.04 appears to be using gcc 4.6.3 Thanks Cheers Richard

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Sample data from Calgary
by mungewell 09 May '12

09 May '12

Here is a 204MByte sample (1MS/s @ LO 866.5MHz) from the Calgary area. http://dl.dropbox.com/u/34518077/HDSDR_20120509_173509Z_866500kHz_RF.wav http://www.radioreference.com/apps/db/?sid=204 This contains a mix of digital and analogue comms, as not all services have switched to digital yet. Simon

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Samples
by davidmcomau 27 Apr '12

27 Apr '12

Anyone know where I can grab a copy of the samples that used to be on the op25 wiki? Interested in getting a copy of the encrypted audio with known key. http://www.sedition.org.au/p25-samples redirects to home page. Thanks, Dave

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RE: HELP lol
by Balint 20 Apr '12

20 Apr '12

OK sorry folks - this is what one should expect when they're dealing with ancient code (I really ought to update at some point!). I've fixed the gr-baz/python/op25.py code to first try the new OP25 blocks (with the slicer), and then fallback to the old version (without the slicer). Let me know if this works! Thanks, Balint

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gr-baz : op25.py has dependence on fsk4
by Richard Clarke 20 Apr '12

20 Apr '12

Hi Balint, I notice that your op25.py module still has a dependence on the old Radio Rausch FSK4 demodulator<http://radiorausch.googlepages.com/GnuradioFourLevelFSK.html> that the OP25 project used to use but have now incorporated into their own source files. I was just wondering if there was any reason you didn't use the op25.fsk4_demod_ff rather instead of fsk4.demod_ff? You have, on the other hand, used the op25 slicer equivalent op25.fsk4_slicer_fb(levels). Just curious. Thanks Cheers Richard On 20 April 2012 11:10, Balint <balint256(a)hotmail.com> wrote: > I’ve just accepted the git pull request submitted by Alex Csete (thank > you!) to fix the build issue on v3.6 of GNU Radio (tested by ‘zignig’), so > if you grab the latest, hopefully this issue will disappear!**** > > ** ** > > (If other people have encountered this problem, please let them know too…) > **** > > ** ** > > *From:* op25-dev(a)yahoogroups.com [mailto:op25-dev@yahoogroups.com] *On > Behalf Of *Richard Clarke > > *Sent:* Friday, 20 April 2012 8:24 AM > *To:* op25-dev(a)yahoogroups.com > *Subject:* Re: [op25-dev] Re: World's cheapest P25 receiver: $20 RTL2832 > dongle + new OP25 Decoder block with DES-OFB for GRC!**** > > ** ** > > **** > > Hi,**** > > ** ** > > I've just tried building the gr-baz module on a couple of different > systems but I'm encountering a make error along the lines of: > ./baz_swig.cc: No such file or directory**** > > ** ** > > I note someone else has also encountered the same error and pasted their > make output to pastebin (http://pastebin.com/y6dUAxC1). This is the same > error I'm getting. Anyone got any clues? Is this a generated file that > isn't being generated, or a file that hasn't been included in the svn repo? > **** > > ** ** > > Thanks**** > > ** ** > > Cheers**** > > Richard**** > > ** ** > > On 6 April 2012 02:14, Balint <balint256(a)hotmail.com> wrote:**** > > **** > > LOL, I thought someone might say that J**** > > **** > > Nice work at that price!!!**** > > **** > > *From:* op25-dev(a)yahoogroups.com [mailto:op25-dev@yahoogroups.com] *On > Behalf Of *ikjtel > *Sent:* Friday, 6 April 2012 12:07 AM > *To:* op25-dev(a)yahoogroups.com > *Subject:* [op25-dev] Re: World's cheapest P25 receiver: $20 RTL2832 > dongle + new OP25 Decoder block with DES-OFB for GRC!**** > > **** > > **** > > **** > > **** > > > Firstly, thank you to Max for the Slashdot mention!**** > > **** > > > Ha ha, it's a pleasure to see this project move forward. > > The cheapest one I've ever built was for $1.00 - picked up an old crystal > scanner at a hamfest that happened to have a crystal in it on the proper > frequency for a local P25 station. It only needed a disc-tap using parts > from the junkbox... > > Max**** > > > > **** > > ** ** > > -- > *SCOTT ADAMS: Normal people believe that if it ain't broke, don't fix it. > Engineers believe that if it ain't broke, it doesn't have enough features > yet.***** > > **** > -- *SCOTT ADAMS: Normal people believe that if it ain't broke, don't fix it. Engineers believe that if it ain't broke, it doesn't have enough features yet.*

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congrats to Balint: on Slashdot ! ! !
by ikj1234i 20 Apr '12

20 Apr '12

http://hardware.slashdot.org/story/12/03/31/1914217/software-defined-radio-…

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