Jim makes some superb points here. The fundamental question is: What noise are you trying to eliminate? Not all noises are created equal, neither are all signals. In my business we are also fond of saying "One man's signal is another man's noise."
This question dictates the design of your (receive) antenna system all the way to the choice of radio, IF and digital filters, etc. Not having read KE7X's book myself (it's on my Christmas list), I cannot be sure how the NR filters in the K3 are implemented. However, appearances are that you select a type of filter and then the agressiveness of that filter. This seems to me that is fundamentally more powerful than the lauded one-knob approach of the FTDX-5000 if the filter you have selected was designed to eliminate the type of noise you are experiencing from the kind of signal you are receiving. I do hope to learn how this is implemented in the K3 and hopefully exploit it to my advantage in the future. Another point---I seem to recall coming across something in the K3 User's Manual about the NR filters being optimized for use in a CW bandwidth (I forget what the exact number was 250-500 Hz or something). If that is the case, then no wonder they don't work in SSB bandwdiths! This is fundamental signal processing. It has little to do with the power the DSP chips or the efficiency of the DSP algorithms. Based on my limited knowledge of noise reduction techniques useful for amateur radio, SSB is a considerably more challenging problem than CW. And it is one the JAs must have apparently mastered. I suspect that they also choose filters based on the bandwidth and mode selected in the radio and it's just transparent to the user. Like Jim, I have been relatively satisfied with the NR in my K3 so far, probably because 1. I'm principally a CW operator, 2. I use it sparingly, 3. I choose to address my noise problems at RF when possible, and 4. I have no interest in buying a $5000 radio that doesn't fit in hand luggage. 73, --Ethan, K8GU/3. On Wed, Nov 7, 2012 at 2:15 PM, W4ATK <w4...@bellsouth.net> wrote: > I have read with interest the e-mails regarding the K3 noise > reduction feature. I will post my observations herewith. It took a bit of > work to find the "sweet spot" setting for my noise environment. Once found, > it has proven to be quite satisfactory. Having worked with a number of SDR > type of radios (Flex, Yaesu, and now K3 and for that matter K2) I can say > that, in my opinion, the K3 is as good as it gets. I sense a number of users > may not be entirely familiar with noise reduction as it pertains to a > software defined radio. In some cases, it seems one is trying to use noise > reduction where one should be using noise blanking, a common mistake in > attempting to reduce impulse noise from power lines. Another common mistake > would be to solicit the settings from another user in a different noise > environment. > > One resource I found to be of benefit to me in helping me to > understand the "processes" of DSP is "The Engineer's Guide to Digital Signal > Processing" by Steven W. Smith. It is a free download from > http://www.dspguide.com. > > 73s, Jim, W4ATK > ______________________________________________________________ > 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 -- http://www.k8gu.com/ Repair. Re-use. Re-purpose. Recycle. ______________________________________________________________ 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
