Thread: Interesting article on fading distortion
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Old July 29th 06, 01:42 AM posted to rec.radio.shortwave
Carter, k8vt Carter, k8vt is offline
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First recorded activity by RadioBanter: Jul 2006
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Default Interesting article on fading distortion
wrote:

Dallas Lankford has done some serious research on the cause and cure
of/for
the distortion caussed by ionospheric "hops".

Interesting! In the RTTY world, this is known as selective fading.
Usually an o'scope is used as a tuning indicator, one set of deflection
plates being connected to the "mark" signal and the other set of
deflection plates being connected to the "space" signal, giving the
classic "cross" display (looks like a 'plus' sign on the screen).

The mark and space signal generally used to be 850 Hz apart, commercial
press stuff 425 Hz apart and most of the stuff today using a 170 Hz shift.

During disturbed ionospheric conditions, you would see this selective
fading come into play; i.e., either the mark or space would fade to
nothing while the other signal was solid--even though they were only 170
Hertz apart.
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