[hpsdr] SDR NB

[Ken]

>>There are a number of ways we could improve the Noise Blanker.

 

>>Many years ago Collins (I think) offered a noise blanker that picked up
wide band local noise in a quiet part of the low VHF spectrum.

 

>>I did some experiments with this idea in the 70's using a 1MHz wide
receiver on about 40MHz. As long as the noise was local and wide band then
it worked really well.

 

There is also the Linrad approach - which is somewhat similar (in that it
effectively listens for the 'noise' in the quiet part of the spectrum). 

 

Linrad uses a transform to the frequency domain and sorts out the really
strong signals (which are on discrete frequencies) from everything else and
runs the NB on the remaining spectrum.  This consists of weak signals and
wideband impulse noise.  They say it works remarkably well. I suppose it
depends on things upstream of the blanker function not getting saturated
and, with Mercury, that might set a limit on what you could do.  But, in a
lot of situations, it would work and it means you can run the noise blanker
without any impact from relatively loud signals elsewhere in the band. This
is a trick "most noise blankers" cannot do.

 

Ken

KE2N

 

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