Re: AM demodulation

[CEL]

Hi Markus,

yeah, that sounds right, but: 
You'd probably want to use a PLL frequency detector (similarly
parameterized) to detect these and output a frequency estimate, and
then do some math on that estimate, and use it to correct the system.

Best regards,
Marcus 

On Mon, 2019-10-28 at 16:41 +0100, Markus Heller wrote:
> Dear OMs,
> 
> I guess this carrier tracking block would be useful to handle
> frequency
> drift of cheap (unstabilized) devices, when working QO-100 satellite
> connections. This block could be used to find the band end beacons
> and
> derive the frequency shift and correct it accordingly. Right?
> 
> vy73
> markus
> dl8rds
> 
> Am Montag, den 28.10.2019, 09:44 -0500 schrieb Bill Dailey:
> > Can you give a little primer on using that PLL tracking?    I would
> > love to use that to just track carriers random frequencies.  For
> > instance 10mhz.  Ultimately I want to track and periodically log
> > and
> > offset from true predicted frequency. Like every 10 seconds.
> > 
> > Bill Dailey
> > 
> > Negativity always wins the short game. But positivity wins the long
> > game. - Gary Vaynerchuk
> > 
> > Don’t be easy to understand, 
> > Be impossible to misunderstand 
> > - Steve Sims
> > 
> > > On Oct 28, 2019, at 9:27 AM, Barry Duggan <address@hidden>
> > > wrote:
> > > 
> > > Hi Albin and Volker,
> > > 
> > > I added a PLL Carrier Tracking block to take care of the tuning
> > > problem. See the revised 
> > > https://wiki.gnuradio.org/index.php/File:FunCube_AM.png
> > > 
> > > Albin, that 'spike' is the carrier! This is AM ;)
> > > 
> > > Thank you both for your suggestions.
> > > ---
> > > Barry Duggan KV4FV
> > > 
> > > 
> > > On 2019-10-27 07:13, Albin Stigö wrote:
> > > > Hi Barry,
> > > > Some thoughts:
> > > > You have a large DC spike at the center, try using the
> > > > frequency
> > > > xlating
> > > > fir filter to tune an offset frequency.
> > > > Why don't you decimate at the channel filter?
> > > > Try observing the signal at various points using the frequency
> > > > sink.
> > > > Good luck,
> > > > Albin SM6WJM
> > > > On Sat, Oct 26, 2019, 21:02 Barry Duggan <address@hidden>
> > > > wrote:
> > > > > Hi,
> > > > > I've been working on a gnuradio AM broadcast receiver, and
> > > > > have
> > > > > found
> > > > > that the tuning is very critical to obtaining clear audio. My
> > > > > flowgraph
> > > > > can be seen at 
> > > > > https://wiki.gnuradio.org/index.php/File:FunCube_AM.png.
> > > > > Are there any alternate demodulation methods which are not so
> > > > > sensitive
> > > > > to exact tuning?
> > > > > Thanks,
> > > > > --
> > > > > Barry Duggan KV4FV
> 
>

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