RadioBanter - View Single Post - possible fix of rumble synch satellit 700

Telamon · September 16th 06, 03:11 AM posted to rec.radio.shortwave

In article ,
(Mark Zenier) wrote:

In article
,
Telamon wrote:
In article . com,
wrote:

Here is the article I found form newsgroup that mention about the way
to eliminate the rumbling noise of synch detector . I hope someone can
study it and give a conclusion on the improvement made be these
modification.

Snip

Some radio stations are off frequency. Use a mode that injects a fixed
receiver local oscillator frequency like CW mode to zero beat the
receiver to the target signal then switch back to sync AM.

And, from a dimly remembered article in QEX many years back, a lot of
shortwave broadcast transmitters have a lot of phase noise. (Speculation:
probably those high effiency transistorized class D ones). Put a
noisy carrier into the servo loop, and the output of the phase detector
will need just the right filters to not carry that through to the VCO.

Do you recall any details of levels and frequencies where the phase
noise was a problem?

--
Telamon
Ventura, California