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PostPosted: Wed Jan 20, 2016 11:21 pm 
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Hm, does this mean that you don't need it? If no one is going to use it it makes no sense to add it. (Of course it could be that people will start using it if I add it...)


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PostPosted: Thu Jan 21, 2016 7:54 am 

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I would need it for a Stereo STL in Europe which will run in this frequency range and also for a project in eastern europe. As new polar stereo coders are hard to find as hardware they are looking for an alternative as this lower FM band will still run for years.


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PostPosted: Fri Jan 22, 2016 1:18 am 
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Ok. If I'm not missing anything, changing both the pilot 19 kHz and L-R modulation 38 kHz frequencies to 31.25 kHz should suffice to do this. So that should be simple. Will put it in, and then wait for your test results.


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PostPosted: Fri Jan 22, 2016 7:39 am 
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I remember i try to send output from ST to the 65-74 band , and all was OK , including the RDS. I was able to see it.


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PostPosted: Fri Jan 22, 2016 10:56 am 

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Thanks Hans, great!


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PostPosted: Fri Jan 22, 2016 6:05 pm 
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So this should be ok?


Attachments:
polar_stereo.png
polar_stereo.png [ 12.99 KiB | Viewed 5266 times ]
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PostPosted: Fri Jan 22, 2016 6:09 pm 
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Edit: No. There is still that K function. Not sure what they do there. Anyway, it would be worth a test to see if you get a stereo signal with this now. It looks like the stereo signal needs to be reduced a lot in amplitude though, so you probably will have FAR too much stereo.

Edit: I really don't understand that K function. And what is j? Or are they complex numbers (j is usually called i then, but it's sometimes called j). Do you have more info about this? I'll send you a beta with this - but without K function - in a few minutes.

Let me know what this version does:
http://www.stereotool.com/download/ster ... 85-016.exe


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PostPosted: Fri Jan 22, 2016 9:20 pm 

Joined: Mon Mar 17, 2014 6:42 pm
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Great, I will do a testsetup on the weekend! Thank

I found this graphic: http://www.radioradar.net/files/Image/a ... c/ris1.gif

"The Soviet system (OIRT in the diagram) transmits the L-R on a double-sideband AM subcarrier centered at 31.25kHz. The 31.25kHz carrier is at a reduced level (one could think of the subcarrier as being suppressed-carrier AM with a low-level pilot tone re-inserted at the carrier frequency, instead of 1/2 the carrier frequency)."

For me it seems to be as followed:

E.g. One Stereo 1 kHz Tone beeing out of phase modulated at 100% should generate 100% modulation in the Stereo AM Part. In this case the 31,25 kHz would normally be as high as the 1kHz tone. Now the carrier is reduced by 14dB but the audio information is as high as before. In the picture it seems that around the carrier there is also a kind of notch filter. Perhaps this is meant by the K-Function?


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PostPosted: Fri Jan 22, 2016 10:50 pm 
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That 14 dB reduction would mean 14 dB less good signal-to-noise ratio for stereo reception. Which isn't that good anyway for normal stereo. But it does look like it. If it's indeed like that, then you should get insane stereo separation for the current sample.

Anyway, let's do this step-by-step. If you do indeed get insane stereo separation, I will reduce it by 14 dB and then you can test again.


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PostPosted: Fri Jan 22, 2016 11:00 pm 
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I'm starting to think that this K formula is actually some pole/zero specification. If so, I need to comply to that exactly to make stereo work properly (without matching it perfectly, the L-R wil be shifted in time vs. the L+R, you'll still get stereo but it will sound weird).


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