Stereo Tool

http://i.imgur.com/Z6EPw2G.png

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Like this:



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.

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!

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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Oh dear No problem!

From rtvforum.net http://www.rtvforum.net/thread-59-post- ... #pid169912

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?

Here is one more, Radio Beograd 1 on 95.3MHz, same password...

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

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.

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.