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.

--
Telamon
Ventura, California

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.


Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)

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

Mark Zenier ) writes:
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.

Wouldn't that be the July 1993 QST article that described a synchronous
detector? I know you've mentioned it before.

I can't put my fingers on the issue, it's around somewhere, and the
reprint in the Handbook leaves off a sidebar or two. And that sidebar
had something about why the author didn't go to a phasing synchronous
detector. He definitely said something about the phase noise of the
receiver's synthesizer, and hence I figure he said something about
the SW transmitters (though I don't recall that bit).

Michael

In article ,
Michael Black wrote:
Mark Zenier ) writes:

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.

Wouldn't that be the July 1993 QST article that described a synchronous
detector? I know you've mentioned it before.

Your mental indexing system is much better than mine. ;-)

I can't put my fingers on the issue, it's around somewhere, and the
reprint in the Handbook leaves off a sidebar or two. And that sidebar
had something about why the author didn't go to a phasing synchronous
detector. He definitely said something about the phase noise of the
receiver's synthesizer, and hence I figure he said something about
the SW transmitters (though I don't recall that bit).

Not if this was that project that used a NE604 and NE602. Rather, It was
an article by the same ham that did the "Synchronous CW" very narrow
bandwidth audio filter project that was in the handbook. (Pettit (sp?),
with a 7 area call, as I remember).

He had come up with a new phase shift keyed very narrow bandwidth system,
and it was just an side comment about what their receiver/decoder could
do. You could hook a 'scope up to it and get a phasor display, and they
were surprised that some of the broadcast stations that they monitored
had the carrier phase dancing all around.

Mark Zenier
Googleproofaddress(account:mzenier provider:eskimo domain:com)