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PostPosted: Wed Feb 10, 2016 1:34 am 
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Joined: Tue Mar 17, 2009 2:56 pm
Posts: 3534
Quote:
A few pics of Serbian radio stations, made by my friend in Belgrade.
http://i.imgur.com/CfMVtq5.jpg
http://i.imgur.com/eVxceMN.jpg
http://i.imgur.com/vlffj4C.jpg
http://i.imgur.com/Pxdh6Et.jpg
Video will soon follow!
http://i.imgur.com/Z6EPw2G.png :)

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PostPosted: Wed Feb 10, 2016 8:35 am 
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Joined: Wed Aug 20, 2014 9:32 am
Posts: 231
Location: Poland
Quote:
Hello everybody!

I'm "the guy" who made those screenshots posted above. Unfortunately I don't have (or I can't see it) an option for 150kHz bandwidth, here is a screenshot from HDSDR:

Image
Like this:

Image

So - samplerate stays 192 kHz, but you need to narrow FM bandwidth to 150 kHz (the closest I can come with HDSDR is 150.977), otherwise the mpx output is about 20% too low.

OR

compensate for the 20% offset (in mpx tool for example). By compensating the signal in MPX tool itself you can actually listen and measure slightly overmodulated signal accurately.

Here the measurements I get from one radiostation that has solid signal in my area:

150 kHz BW - pilot 9.5% (+/- 0.1%)
192 kHz BW - pilot 7.5%

And I'm pretty sure 9.5% is accurate

Bojcha used different method, with modified tuner that has mpx output - it's the most accurate way of measuring signals, provided you know how (and are able to) calibrate the whole system, including line input in your soundcard.


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PostPosted: Wed Feb 10, 2016 7:16 pm 

Joined: Mon Feb 08, 2016 3:55 pm
Posts: 3
Location: Belgrade, Yugoslavia
Thanks a lot!

Totally missed that, as a matter of fact it wasn't even visible to me, I had to click on AM then back to FM to get that slider, and as you said the closest bandwidth is 150.977

I'll post new pictures in a few days!


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PostPosted: Mon Feb 22, 2016 1:18 pm 
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Joined: Tue Mar 17, 2009 2:56 pm
Posts: 3534
I should like to thank Slawomir for sending me a one USB dongle with RTL2832!
Now i can play with it too :)
Thanks Slawo!

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PostPosted: Fri Feb 26, 2016 11:29 am 
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Joined: Wed Aug 20, 2014 9:32 am
Posts: 231
Location: Poland
Oh dear :) No problem! :D


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PostPosted: Mon Mar 07, 2016 5:34 pm 

Joined: Tue Jan 26, 2016 11:34 pm
Posts: 54
Location: Jugoistočna Srbija
From rtvforum.net
Quote:
http://www.rtvforum.net/thread-59-post- ... #pid169912


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PostPosted: Sat Mar 12, 2016 7:46 pm 

Joined: Tue Jan 26, 2016 11:34 pm
Posts: 54
Location: Jugoistočna Srbija
The promised videos are here! Both videos are password protected - the password is rtvforum.
Domo-kun sent them to me via private message. :)
Play 92.5: http://www.dailymotion.com/video/x3xg55u
Radio S 94.9: http://www.dailymotion.com/video/x3xg5ob
Both videos are showing speech segments. I don't understand why bandwidth increase does nothing to the distortion in the Play 92.5 video?


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PostPosted: Sat Mar 12, 2016 9:05 pm 

Joined: Mon Feb 08, 2016 3:55 pm
Posts: 3
Location: Belgrade, Yugoslavia
Here is one more, Radio Beograd 1 on 95.3MHz, same password...

http://www.dailymotion.com/video/x3xh5u9


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PostPosted: Mon Mar 14, 2016 12:11 pm 
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Joined: Wed Aug 20, 2014 9:32 am
Posts: 231
Location: Poland
Quote:
The promised videos are here! Both videos are password protected - the password is rtvforum.
Domo-kun sent them to me via private message. :)
Play 92.5: http://www.dailymotion.com/video/x3xg55u
Radio S 94.9: http://www.dailymotion.com/video/x3xg5ob
Both videos are showing speech segments. I don't understand why bandwidth increase does nothing to the distortion in the Play 92.5 video?
Might be multipath - please note how asymmetric the signal is. Maybe received signals were overlapped with the reflected ones. I've seen same while testing the receiver between tall buildings.


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PostPosted: Mon Mar 14, 2016 2:01 pm 

Joined: Tue Jan 26, 2016 11:34 pm
Posts: 54
Location: Jugoistočna Srbija
92.5 and 94.9 are coming from the same transmitter location with similar power, yet 94.9 has no distortion (except that induced by Optimod) so I doubt it's multipath. About the asymmetric signal, you think of the 95.3 signal? That's because 95.3 is running without audio processor, so there is nothing to symmetrify asymmetric voice.


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