Topband: Any Linrad selective limiter noise blanker experts here?

[Richard (Rick) Karlquist]

On 1/20/2020 7:43 AM, Tim Shoppa wrote:
> 
> But in a 160 contest with a huge density of loud local signals, the rigs
> noise blanker's action just mixes all the super-loud dense signals together
> and isn't really effective anymore.
> 
> Tim N3QE tshoppa at gmail.com
> _________________

In most cases, line noise is a repeating function with a frequency of
50 or 60 Hz.  To make an  effective noise blanker in a contest, you
simply have to make a filter that only responds to harmonics of the
line frequency and then generate the inverse function from a 50 or
60 Hz line clock.  The filter averages many instances of the impulse
and the QRM averages away.  As contrasted to conventional NB circuits 
that create each blanking pulse in real time, as if they are all
different, which would be the case for say ignition noise.  This was 
actually done many years ago with analog hardware.  It could be 
described as a Kalman filter.  It should be a simple DSP problem.

I have tried to suggest this idea to engineers at various SDR vendors,
but got nowhere with it.

I don't know if the LINRAD blanker does anything like this.

Rick N6RK