The upper audible range for telephonic conversations could be around 2k-
6kHz,
while for a FM quality transmission it could be likely around 12k - 15kHz
(The upper limits, of course)

If a DSP is available, a filter that runs around those lines could
determine the
lines drawn between the actual audio data and white noise, probably.


On Mon, Jun 25, 2012 at 12:36 AM, Yigit Turgut <y.turgut@gmail.com> wrote:

> What are the characteristics of nominal FM output range and noise
> range ? There should be a reference point for classification. A filter
> -might- also help but it will highly depend on the noise
> characteristics since it will perform a frequency based
> classification.
>
> On Sun, Jun 24, 2012 at 9:57 PM, Manu Abraham <abraham.manu@gmail.com>
> wrote:
> > Hi,
> >
> > Maybe a filter could help ?
> >
> > Regards,
> > Manu
> >
> > On Sun, Jun 24, 2012 at 10:50 PM, <enkitec@gmail.com> wrote:
> >
> >>
> >>
> >>     Hi,
> >>
> >>     I want to build a FM radio squelch using a microprocessor with an
> ADC.
> >>     The ADC will be sampling the FM radio audio output and turn on a
> >> LED when there is only noise present. The LED will be off when someone
> >> is using the channel (no noise, just voice).
> >>
> >>     What is the best way of doing this in software?
> >>
> >>     Thanks for any idea.
> >>     Mark Jordan
> >>
> >>
> >>
> >>
> >>
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