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From: RFguy on 6 May 2008 19:35
Is there a digital technique for detection of the 19 kHz stereo pilot on
commercial FM broadcasts?

I'm looking for a way to extract the unmodulated pilot tone (only) from the
analog RF carrier at low C/N ratios that would be below threshold with a
conventional discriminator.

Thanks.



From: Vladimir Vassilevsky on 7 May 2008 01:44


RFguy wrote:

> Is there a digital technique for detection of the 19 kHz stereo pilot on
> commercial FM broadcasts?

It depends.

> I'm looking for a way to extract the unmodulated pilot tone (only) from the
> analog RF carrier at low C/N ratios that would be below threshold with a
> conventional discriminator.

Depending on what do you need exactly, it could be possible to extract
the pilot tone when the SNR is substantially below the threshold of the
normal reception.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
From: kronecker on 7 May 2008 05:32
On May 7, 5:44 pm, Vladimir Vassilevsky <antispam_bo...(a)hotmail.com>
wrote:
> RFguy wrote:
> > Is there a digital technique for detection of the 19 kHz stereo pilot on
> > commercial FM broadcasts?
>
> It depends.
>
> > I'm looking for a way to extract the unmodulated pilot tone (only) from the
> > analog RF carrier at low C/N ratios that would be below threshold with a
> > conventional discriminator.
>
> Depending on what do you need exactly, it could be possible to extract
> the pilot tone when the SNR is substantially below the threshold of the
> normal reception.
>
> Vladimir Vassilevsky
> DSP and Mixed Signal Design Consultanthttp://www.abvolt.com

Use a PLL locked into 38kHz and divide by two.

K.
From: RFguy on 7 May 2008 11:35
It's easy to explain what I'm trying to do: I want to extract the 19 kHz
tone without having to do conventional demodulation of the entire FM signal.
The reason for this is to get around the demodulator threshold and be able
to work at lower values of C/N than a discriminator would permit.

But knowing how to do that is tough. The modulated FM signal is complex.
It contains mostly random audio and the one unmodulated tone. I'm thinking
that a tracking filter might work because the 19 kHz is the only coherent
signal in the baseband. Any suggestions on search terms or general approach
would be appreciated.



"Vladimir Vassilevsky" <antispam_bogus(a)hotmail.com> wrote in message
news:bjbUj.14573$V14.544(a)nlpi070.nbdc.sbc.com...
>
>
> RFguy wrote:
>
>> Is there a digital technique for detection of the 19 kHz stereo pilot on
>> commercial FM broadcasts?
>
> It depends.
>
>> I'm looking for a way to extract the unmodulated pilot tone (only) from
>> the analog RF carrier at low C/N ratios that would be below threshold
>> with a conventional discriminator.
>
> Depending on what do you need exactly, it could be possible to extract the
> pilot tone when the SNR is substantially below the threshold of the normal
> reception.
>
>
> Vladimir Vassilevsky
> DSP and Mixed Signal Design Consultant
> http://www.abvolt.com


From: Mark on 7 May 2008 14:23
On May 7, 11:35 am, "RFguy" <NoBodyH...(a)SSSpamavoidance.com> wrote:
> It's easy to explain what I'm trying to do: I want to extract the 19 kHz
> tone without having to do conventional demodulation of the entire FM signal.
> The reason for this is to get around the demodulator threshold and be able
> to work at lower values of C/N than a discriminator would permit.
>
> But knowing how to do that is tough.  The modulated FM signal is complex..
> It contains mostly random audio and the one unmodulated tone.  I'm thinking
> that a tracking filter might work because the 19 kHz is the only coherent
> signal in the baseband.  Any suggestions on search terms or general approach
> would be appreciated.
>
> "Vladimir Vassilevsky" <antispam_bo...(a)hotmail.com> wrote in message
>
> news:bjbUj.14573$V14.544(a)nlpi070.nbdc.sbc.com...
>
>
>
>
>
> > RFguy wrote:
>
> >> Is there a digital technique for detection of the 19 kHz stereo pilot on
> >> commercial FM broadcasts?
>
> > It depends.
>
> >> I'm looking for a way to extract the unmodulated pilot tone (only) from
> >> the analog RF carrier at low C/N ratios that would be below threshold
> >> with a conventional discriminator.
>
> > Depending on what do you need exactly, it could be possible to extract the
> > pilot tone when the SNR is substantially below the threshold of the normal
> > reception.
>
> > Vladimir Vassilevsky
> > DSP and Mixed Signal Design Consultant
> >http://www.abvolt.com- Hide quoted text -
>
> - Show quoted text -

I'm thinking you could try a threshold extension FM demod where the
tracking BW is wide enough to track out most of the audio and leave
just the 19kHz modulation which you then demodulate.

Never seen it done though...

Mark
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