"Another Better Mouse-trap?"

[William Carver]

"IMHO, the problem with most blankers, as mentioned below, is that the
designers don't introduce any delay in the signal path.  It takes some
time to amplify, detect and form the blanking pulses that drive the
noise gate.
Absent delay, the noise pulses get through the gate and do their
mischief before the blanking takes place."

That's right: the blanking pulse needs to open the gate before the
signal+noise pulse gets there. You can either delay the signal, or you
make the blanking pulse so quick that it naturally arrives there before
the signal. A wideband noise receiver can have less delay than the
receiver, and blanking pulses can be generated in nanoseconds with
todays fast circuits, so it can sometimes be done without a delay in the
signal path.

W7AAZ



______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Geoffrey Mackenzie-Kennedy]

A noise gate placed in the signal path can be a source of IMD products, even
when it is not active.

IMHO a separate noise receiver which can be tuned over a limited frequency
range above the band in use to avoid "real" signals, whose output inhibits
LO drive when noise is present, plus the required delay in the signal path,
is a useful recipe for a noise blanker.

73,
Geoff
GM4ESD

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Eric Swartz - WA6HHQ]

We do add the needed delay as needed on the K2 and K3.

73, Eric  WA6HHQ
Elecraft
===

William Carver wrote:

> "IMHO, the problem with most blankers, as mentioned below, is that the
> designers don't introduce any delay in the signal path.  It takes some
> time to amplify, detect and form the blanking pulses that drive the
> noise gate.
> Absent delay, the noise pulses get through the gate and do their
> mischief before the blanking takes place."
>
> That's right: the blanking pulse needs to open the gate before the
> signal+noise pulse gets there. You can either delay the signal, or you
> make the blanking pulse so quick that it naturally arrives there before
> the signal. A wideband noise receiver can have less delay than the
> receiver, and blanking pulses can be generated in nanoseconds with
> todays fast circuits, so it can sometimes be done without a delay in the
> signal path.
>
> W7AAZ
>  

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html