>FWIW I have a Perseus and two other receivers which both use H-Mode mixers, > one of which uses a version of PA3AKE's H-Mode front end. > > With the Perseus used as a stand alone receiver, I have not experienced > this > "noise problem" in the presence of mild or quite strong static or manmade > pulse QRN, UNLESS I wind up the Perseus' NR too far, then indeed there is > some tunnel/ reverberation effect, which can at times be annoying.
I think people are talking about two different things here. What I am talking about, and what I understand some others to be talking about, is a problem with DSP systems processing noise floor signal, especially when the noise is a bit rough, without adding artifacts that make copy or quality worse. This is not anything to do with noise blanker use, which would have limited use with a weak noise-floor signal. Processing with a noise blanker punches a hole or reduces gain for fast level increases, and noise blanking in a DSP is a different process. I'm not sure what goes on now, but years ago when I worked on some DSP NR systems it was necessary to compare many samples of signal and look for repeating patterns that would be a steady signal and try to subtract out things that did not repeat. This always caused a delay or echo or distortion, depending on the aggressiveness of the noise reduction. I fully expect any kind of blanker or processor to screw up the signal characteristics. There is no way around it. :-) My concern is when the processing is off and there should be a faithful accurate reproduction of signal, even when it is below noise floor. I have no problem at all with how the K3 blanker and noise reduction works, and actually IMO it does a good job for me. I just don't think any DSP radio is as good as a full analog system when signal levels are near noise levels, especially when the noise floor is a bit rough. 73 Tom ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
