On 1/28/2013 7:55 AM, Shoppa, Tim wrote:
I think it's possible that some of the modern DSP rigs may have unusual
(impulse) AGC artifacts in a strong signal environment. Having noise blanker
turned on may make keyclick-sounding artifacts too.
Absolutely -- clicks can be generated in the RX by a noise blanker, and
by overload of a receiver. And yes, a noise blanker that samples a
broadband signal and uses it to cancel or gate noise will make a loud
signal sound broad. Nowadays though, many of us have a good spectrum
display running, and can look at many signals and compare them. I'm
using a P3, which I can expand to a display that's as little as 2kHz
wide, and anything up to 200 kHz, and with any vertical scale up to
about 80 dB. When I'm looking at signals for bandwidth, I set the
detector in peak mode, so that I can see the sidebands. When you do
this, the differences between clean radios and dirty ones jumps out at
you. Naturally, you've also got to make certain that nothing in your
system is getting overloaded.
And I DID contact each of the guys whose calls I cited during the
contest. In fact, I contacted AC6DD about this issue two years ago when
he was making a mess in the JA window during the winter Stew, and two
years later his signal is still trashy.
73, Jim K9YC
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Topband Reflector
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