[TenTec] Corsair II noise blanker

[Ken Brown]

There are many kinds of noise blankers. They differ in the way they 
decide when to blank the signal (their triggering source), where in the 
signal path they perform the blanking, and the timing of the blanking.

The most common variation, the ones built in to most ham rigs, uses a 
noise pulse detector in the IF stage of the receiver to generate the 
triggering of the blanking. In most cases this noise detector is before 
any narrow filtering, but likely after a fairly wide IF filter.

The blanking occurs further down the IF path, but also before any narrow 
filters that would likely spread the noise pulse out in time.

Timing (after the triggering) and the duration of the blanking may be 
adjustable, or just some fixed value the designer thought would work 
well in most situations.

Other variations may get the triggering from a completely different 
receiver and/or antenna from the one that is being blanked. 
Triggering/synchronization from the AC mains power can also be effective 
if noise from the AC mains is greatest source of noise.

The blanking can be done between the antenna and the first stage of the 
receiver that is being blanked. Or it could even be done in the audio 
stages. Or somewhere in between. In most cases earlier in the signal 
chain before the strong noise pulses overload any stages or spread out 
in time due to filter ringing is going to work better than doing it at a 
later stage.

DE N6KB