Topband: Coupla things

[Jim Brown]

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