[Elecraft] Distortion while using NB?

[wayne burdick]

JIM DAVIS wrote:

> With alot of the newer rigs with "noise-blankers" it's always been the 
> case whereby
> when they are activated there's always a small amount of distortion 
> that's injected
> into the audio we hear, either via our speaker or from the headphones!
>   So what I'm asking is it possible (eventually) that through firmware 
> manipulation that
> that (irksome by-product) will ever be able to be eliminated or at 
> least smoothed out
> a tad bit more???

Hi Jim,

The answer depends on the type of noise. An I.F. blanker like the K3's 
can, in many cases, completely remove pulse noise such as that from 
power lines without any type of audio artifact. But some noise has such 
a high duty cycle that blanking it creates unavoidable "holes" in the 
signal. Also, an I.F. blanker can generate audible IMD if there happen 
to be high-amplitude signals in its input passband.

To mitigate these problems, the K3 provides a wide range of blanking 
pulse width and sensitivity settings in its I.F. blanker, and also 
provides a DSP-based blanker that has many possible settings. The DSP 
blanker is far less likely to be impacted by off-channel signals 
because it is post-crystal-filter. In many cases the I.F. and DSP 
blankers can be used together to optimize noise rejection.

We're always looking at new noise blanking techniques for both the I.F. 
blanker (hardware) and the DSP blanker (firmware). In the future we may 
be able to offer adaptive blanking and signal reconstruction either at 
I.F. or DSP. Any hardware advances would be easily retrofittable to 
existing K3s because the KNB3 is a separate module, and firmware 
improvements are always free of charge.

73,
Wayne
N6KR

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