Auto Notch Filter Freeze
Locked
 
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I guess I should have posted this in the K3 section and not in the Electraft section.
In January and October of 1992 I wrote two QEX articles on a project that another Ham and I worked on called the "Hamblaster". We developed a DSP based sound card that used filter programs for noise reduction and auto notch. A feature that we added proved to be quite interesting in some respects and corrected problems where the DSP was outside the AGC loop. First of all the Hamblaster had its own AGC loop that maintained an optimal baseband level. There was an on screen option to freeze filters. My theory was "Why design an auto notch that continuously adapts". You only need to converge on the interfering carrier once. After that, there's no need to re-adapt. If the interfering carrier changes, to readapt, you can press the auto notch button again. Because everything was done in software, we added buttons on the PC screen where you can set a parameter to automatically freeze the auto notch after a given time or you can manually freeze it. This worked well and after the notch was locked to carrier, there was no distortion. We even added a freeze button on the noise reduction. I noticed that when the filter adapted to ones voice. The LMS algorithm was, for the most part, was optimized to the person's voice characteristics and the filter was optimal for the whole QSO. The drawback was that it took several tries to get it right. Some times the filter lock on the high frequency elements of speech and other times on the low frequency components but it reduced noise to a certain degree without the usual artifacts in the noise floor. I thought that this would be an interesting feature to add to the K3 in the next firmware upgrade. Jack WA9FVP Willco Electronics.
Jack WA9FVP
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Probably doesn't matter much, since "sections" are only seen/used by those
who read the Nabble list on-line. Messages posted to Nabble are (eventually) copied directly to the main Elecraft email list-serv without any category or section. I believe the Elecraft pricipals involved- That is Wayne, Eric, and DSP guru Lyle (who is currently on vacation, I believe), read via the mailman.qth reflector, not Nabble. So, for the most part, not of that Nabble categorization matters, except to the minority that read there. That said, I like the sound (no pun intended- or was it...) or you suggestion. I think it is worth examining the possibility. Thanks for bringing it up. 73, Bruce, N1RX > I guess I should have posted this in the K3 section and not in the Electraft > section. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Why are you sending this to me? -Robby VY2SS From: Bruce Beford-2 [via Elecraft] [mailto:[hidden email]] Probably doesn't matter much, since "sections" are only seen/used by those If you reply to this email, your message will be added to the discussion below: http://elecraft.365791.n2.nabble.com/Auto-Notch-Filter-Freeze-tp7564757p7564760.html To start a new topic under [K3], email [hidden email] |
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In reply to this post by wa9fvp
Please do not send these emails to me. -Robby VY2SS From: wa9fvp [via Elecraft] [mailto:[hidden email]] I guess I should have posted this in the K3 section and not in the Electraft section. Jack WA9FVP If you reply to this email, your message will be added to the discussion below: http://elecraft.365791.n2.nabble.com/Auto-Notch-Filter-Freeze-tp7564757.html To start a new topic under [K3], email [hidden email] |
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