---- Steve Glass stevie.glass@gmail.com wrote:

Ok, I've fixed up the link to the samples so there's one capture up there right now. I'll upload other samples if people send me the link tellling me where I can upload them from. Of course, we want them compressed using bzip2 first ;-)

On 10 March 2013 01:03, md123@nycap.rr.com wrote:

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Hi everybody!

I would have thought that there would be samples the web but i have been unable to find any and the link on osmocom is broken. I am in need of some signal samples so i can familiarize myself with the scopes and how the signals look in them. I want to start with P25 but I really need to be familiar with all sorts of signals so sharing of any kind of signal will be much appreciated.

Thanks! Matt

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Hi, I'm still working in the theoretical part before that I use an USRP so I need a signal sample too. Is it from this page that you took it? http://op25.osmocom.org/trac/wiki.png/wiki/SamplesPage

You just have to put it in the filesource section to use it right? What I don't understand is how you configure the following sections (like the center frequency etc..) and how the .dat.info file is suppose to help you (i's like there are almost no information inside the file)?

Thanks in advance for your awnsers

Souf

--- In op25-dev@yahoogroups.com, <md123@...> wrote:

---- Steve Glass <stevie.glass@...> wrote:

...

Ok, I've fixed up the link to the samples so there's one capture up there right now. I'll upload other samples if people send me the link tellling me where I can upload them from. Of course, we want them compressed using bzip2 first ;-)

Thanks a bunch Steve, big help! I have been able to get he signal on the scopes but unable to hear any sound. Do you have any ideas about what may be wrong here?

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1

On 03/31/2013 07:22 PM, souf308 wrote:

OK I think I actually found out how to use the info file. But I still need some help to configure the parameters in the OP25.grc and use the samples (sorry to bother you with those beginners questions) ---------------------------- Here is the info file (from the website) (dp0 S'capture-rate' p1 I250000 sS'source-decim' p2 I256 sS'source-dev' p3 S'USRP' p4 sS'center-freq' p5 F434075000.0 s. --------------- So * 'capture-rate' corresponds to the parameter 'samp_rate' in grc file hence samp_rate=250000

• 'center frequency'=434075000.0

*but what about 'channel_rate'? (=250000?)

*In this formula (channel_rate/(2.0 * math.pi * op25.SYMBOL_DEVIATION)) what is op25.SYMBOL_DEVIATION???

*what is samp_per_sym??

Thanks in advance for you help

Souf

Hi Souf, yes the capture rate is the sample rate. sample per symbol is what changes the channel rate, don't change the channel rate directly; I believe the channel rate should be between 19.2k and 43.2k. decimation changes the pre_channel rate, looks like he had it set at 256. I have found that it is best to play a file is with the flow graph set exactly as it was set when the file is captured. If you want to have a go with a capture I made I put the file up for download at: http://www.fileswap.com/dl/9kfgeOXMz/ I think the frequency, sample rate, decimation, and symbol_per_sample information is in the tar file. put a throttle right after the file source or the file will play in about 11 seconds instead of the real speed of about 40 seconds. so when you play the file first you tune to the frequency, next on the BB-1 tab you wait for the carrier freq to pop up, then go to the X-late1 tab and use the offset to get the channel at zero and narrow the bandwidth with the xlateBW slider, then go to the Dbits tab select autorange and change the marker to dots. you'll see the dots go from scattered into 4 perfect lines and you'll hear the transmission. Thanks