Tom Wylie wrote:
Is it possible to get noise reduction working when in Data mode like
RTTY?
How would data reduction work in such modes and, more importantly, why
are those techniques not already being used in your data terminal?
Real noise can never be reduced; it is random, and therefore impossible
to predict. What I think the K3 noise reduction may be doing is:
- automatic interference reduction, by automatically notching out
constant carriers - but a marking RTTY signal looks like a constant
carrier and would also be removed by this;
- squelching when there is no speech like signal;
- selectively reducing gain at frequencies which don't have strong
spectral peaks from the speech.
The latter two reduce subjective noise, but are only valid for speech.
They work because speech is a relatively inefficient user of bandwidth,
but has a lot of redundancy.
The best way of getting rid of interfering carriers is to use a narrow
passband, either at IF, or in the terminal unit and the best way of
mitigating random noise is by using a discriminator that is well matched
to the desired modulation.
Tom
GM4FDM
--
David Woolley
"The Elecraft list is a forum for the discussion of topics related to
Elecraft products and more general topics related ham radio"
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