If I remember correctly it was Collins who first came up with the idea of
using a simple secondary 'noise receiver' to blank the main receiver in HF
SSB mobile installations using the KWM -1 and / or KWM-2A transceivers. The
secondary 'noise' receiver was tuned to a frequency above 30 MHz and
On Jun 5, 2008, at 8:44 PM, Ron D'Eau Claire wrote:
Aaargh! I meant to say we used high level I.F. limiters so no AM
would get
to the detector. That included noise.
Right. If you use a discriminator there was amplitude sensitivity in
the detector so limiters stages were used in the IF
Yesterday I discovered by accident (or stupidity) that if you have Noise
Reduction engaged and you go to FM mode, you do not receive any intelligible
signals. You can tell that there is a signal, but you cannot make it out.
I realize that there is no earthy reason to use NR in FM. But, if
@mailman.qth.net
Sent: Thursday, June 05, 2008 7:34 AM
Subject: [Elecraft] K3: Noise Reduction (NR) in FM Mode
Yesterday I discovered by accident (or stupidity) that if you have
Noise
Reduction engaged and you go to FM mode, you do not receive any
intelligible
signals. You can tell that there is a signal
The Motorola and GE 2-way mobile radios with noise blankers
were just that ... noise blankers ... that worked in the IF chain
and blanked (turned off) the IF's for the duration of a noise pulse.
They were primarily found in low band (30 - 50 mHz) radios and
were aimed at ignition noise. The NB's
???
I worked on FM gear in the land mobile business as a service rep and
salesman and we *never* used a noise blanker. A limiting I.F. amplifier was
a basic part of the receiver design since the detector does not respond to
amplitude modulation at all, including noise.
Noise does not modulate
Aaargh! I meant to say we used high level I.F. limiters so no AM would get
to the detector. That included noise.
So blankers were never needed.
Maybe Motorola didn't use good limiters.
Now to see if I can pry my foot out of my mouth...
Ron AC7AC
-Original Message-
???
I worked on
At least with the Motorola Syntor X, they used a separate and very
simple receiver to pick out impulse noise and used this secondary RX
detector output to poke holes in the main RX audio. They called it an
Extender and I believe it was only included with the low-band Syntor
X. It is described as
@mailman.qth.net
Sent: Thursday, June 05, 2008 8:12 PM
Subject: RE: [Elecraft] K3: Noise Reduction (NR) in FM Mode
???
I worked on FM gear in the land mobile business as a service rep and
salesman and we *never* used a noise blanker. A limiting I.F.
amplifier was
a basic part of the receiver design
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