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Re: [linrad] AM and FM

Hi Leif,

It will be interesting to see if you make a noise blanker that
works on FM. The Ham rigs fail badly at that.

One idea comes to mind, perhaps down the road on FM.
When you expect a 5Khz deviation FM signal, you could set
the maximum IF bandwidth properly as an initial setting.
The dynamic bandwidth of the signal would then be measured
and the IF filter bandwidth would be changed quickly to match
the instantanious deviation level. The result should be an improvment
in S/N especially at times that the transmitter is not fully modulated.
This would feature would be much easier in software then in hardware.
A noise operated squelch would then have to operate with a fixed IF
bandwidth on a separate detector.

I found your text on AM. It is interesting reading.

73, Jim Shaffer, WB9UWA.

On 14 Jan 2004 at 20:46, Leif Åsbrink wrote:

> Hi all,
> Linrad01-11 is now uploaded.
> This version has detectors for AM an FM.
> Coherent processing is an advantage in AM and I
> have written a page about that.
> The FM mode is just a conventional FM detector,
> enhancements are possible, but I have not yet any
> suitable (marginal) FM signals to play with....
> 73
> Leif  /  SM5BSZ