Jerry,
That not quite what Toby's talking about.
The old noise blankers used a noise sample in a wideband receiver to
perform a short (not extended by selective filters) duration receive
mute, much like current noise blanlers operate except they pull a sample
at the operating frequency from early in the receiver.
The noise cancellers work in a different way. Instead of shutting off
the receiver they have a phase and amplitude adjustment that allows the
noise reduction signal to cancel the input from the regular antenna.
This allows removal of even CW signals, or in band QRM if the directions
are different. See Aug 06 QST, p 45 for more, if you like.
73, Joel Hallas, W1ZR
Dr. Gerald N. Johnson wrote:
>On Sat, 2007-01-27 at 21:14 -0500, Toby Pennington wrote:
>
>
>>It's too bad that modern transceivers don't incorporate some of the features
>>such as the MFJ 1026 exhibits. By using a noise canceller ahead of the
>>antenna input you can null the offending noise before it gets into the
>>receiver.
>>
>>Of course then you would have to install some kind of noise antenna by which
>>you could phase or null the noise out.
>>
>>I believe that in the next ten years noise will be one of the major problems
>>for ham radio operators. There are more and more part 15 devices coming out
>>on the market now, and it just keeps getting worse as time goes by, not to
>>mention power line problems.
>>
>>I suggest that some of the manufacturers look in to this and see what can be
>>with adding noise cancellers like the MFJ1026 unit. There may be others,
>>but I am just familiar with this particular one.
>>
>>It would be great to see Ten Tec incorporate such a device in their rigs.
>>
>>Toby W4CAK
>>
>>
>
>That's exactly how the Collins noise blankers worked for the KWM-2 and
>the S-line more than 40 years ago. They used a 40 MHz antenna for the
>noise receiver thinking mostly automotive ignition noise and close by
>power line noise. Wouldn't work well on 75 meters with a line noise
>source a mile away.
>
>73, Jerry, K0CQ
>
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>
>
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