Wayne: Your mention of some reconstructive algorithms was very interesting to me. For some time, I've wondered if it would be possible to have a circuit which would regenerate a CW signal and play it back in a noise free environment. I'm not an engineer, but I seem to remember that work was done a number of years back with UARTs and the like to regenerate fading or noisy TTY signals and they seemed to work reasonably well. At the very least, such a system might provide considerably improved copy under heavy noise conditions. I don't know of any other radio currently using audio reconstruction. Perhaps it's because it doesn't work or hasn't been high on the priority list. In any case, I think it's a very interesting idea.
Bruce -- W8FU -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of wayne burdick Sent: Tuesday, June 12, 2007 11:58 AM To: Kenneth A. Christiansen Cc: [email protected] Subject: [Elecraft] Re: K3 Noise Blanker ahead or behind roofing filter? Hi Ken, The short answer is "both". The 1st I.F. noise blanker module is ahead of the roofing filters, so it can blank wideband pulse noise. It has a wide AGC range and various threshold and blanking width settings. There's also a DSP noise blanker *after* the roofing filters. This blanker has the advantage of not being modulated by signals outside the roofing filter bandwidth. Of course you can't use it in all cases, because the roofing filter stretches the pulses and thus requires longer blanking times. But I have some noise on 160 m that the DSP blanker suppresses by some 40 dB, making otherwise completely inaudible signals stand out clearly. We're also experimenting with reconstructive blanking algorithms to make the DSP blanker even more effective. The noise blanker LEVEL switch displays the parameters for both the hardware blanker and the DSP blanker on the VFO A and VFO B displays. You can then adjust either or both to see which is most effective on noise. The settings are stored on a per-band basis. 73, Wayne N6KR On Jun 12, 2007, at 4:50 AM, Kenneth A. Christiansen wrote: > Is the noise blanker on the K3 ahead of the roofing filter or behind > the roofing filter....? --- http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
