Subject: "Another Better Mouse-trap?"
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Subject: "Another Better Mouse-trap?"
 
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This idea was put forth by "Don-W6JL" (Fallbrook, CA)!!! His quote: " I have tested many "noise blankers" in modern rigs, on the air. Both the I.F. noise gates and the DSP-based noise reducers. Not one works the way I feel it should. I think you need a separate noise receiver, independent of the main receiver, and tuned to a frequency that is outside of a ham band. (There have been excellent homebrew receivers using this approach for noise blanking). This then drives the noise gate, and is timed so that it gates the I.F before the noise pulse arrives there. A good blanker should have 40 dB minimum of noise pulse suppression, with adjustable blanking level and widths. I notice the K3 has these features, but it still does not seem to reduce impulse noise more than an S unit or two (6-12 dB), which is inadequate. I do not use blankers here myself; my entire station is homebrew and the receiver is a phasing, image cancelling job with no blanking at all, (or AGC for that matter). I get along fine with neither, even in contests." ****************************************************************************************** Eric-WA6HHQ & Co. + All the loyal "K3ers" WHADDAHYA THINK??? Jim/nn6ee ______________________________________________________________ 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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The initial patent for the concept of a separate "noise receiver"
detecting noise and blanking the IF system was issued to Motorola for use in their "low band" ... 27 - 54 mHz ... 2-way radios. They called it a "range extender", and this was the label on the control heads that turned the feature on and off. 73! Ken Kopp - K0PP [hidden email] ______________________________________________________________ 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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In addition to Motorola, didn't Collins use this approach with the
KWM-2? I recall the noise receiver as operating around 40 MHz, which is a peak frequency for spark plug noise. Jack K8ZOA Ken Kopp wrote: > The initial patent for the concept of a separate "noise receiver" > detecting noise and blanking the IF system was issued to Motorola > for use in their "low band" ... 27 - 54 mHz ... 2-way radios. They > called it a "range extender", and this was the label on the control > heads that turned the feature on and off. > > 73! Ken Kopp - K0PP > [hidden email] > ______________________________________________________________ > 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 > > 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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In reply to this post by JIM DAVIS-11
Hi All,
I've had many QSO's with Don, W6JL, on 40 CW. He hangs out there nearly every morning. His station is ALL homebrew, a fact he will beat you to death with everytime you talk to him. In fact, much of his station lays across his desk in sections, rather than "neatly" packaged in a case. But he is an inveterate builder and tinkerer, and I think he knows a lot! I guess having his station in pieces like that makes it easier for him to make changes and experiment. Don's comments that you quoted don't surprise me at all. He doesn't think much of commercial gear, and insists that "rolling your own" isn't difficult. For him maybe, but not necessarily for everyone. Nevertheless, his comments about noise blankers do make a lot of sense. And I bet he has investigated a bunch of them. What he describes as a better system seems to closely related to noise cancelling devices like the JPS NIR-10, and others. But I'm sure Don has a somewhat different approach in mind--he does mention using a receiver, rather than an accessory. I would bet money that Don's suggestion is a good one. It won't be as easy as he will make it sound, but it would probably not be terribly hard either. If you talk to Don, he would also probably be happy to tell you just how you could do it, and probably where you could info to build what you need. He has a great command of what you can find on the internet. In his words, "you can find just about anything you need on the internet." The only caveat is that he will probably want you to build it, rather than buy it. It's a shame Don doesn't publish some of the stuff he like to talk about. Maybe he has, and I just missed it. Dave W7AQK ----- Original Message ----- From: "JIM DAVIS" <[hidden email]> To: <[hidden email]> Sent: Friday, August 07, 2009 1:42 PM Subject: [Elecraft] Subject: "Another Better Mouse-trap?" This idea was put forth by "Don-W6JL" (Fallbrook, CA)!!! His quote: " I have tested many "noise blankers" in modern rigs, on the air. Both the I.F. noise gates and the DSP-based "noise reducers". Not one works the way I feel it should. I think you need a separate noise receiver, independent of the main receiver, and tuned to a frequency that is outside of a ham band. (There have been excellent homebrew receivers using this approach for noise blanking). This then drives the noise gate, and is timed so that it gates the I.F before the noise pulse arrives there. A good blanker should have 40 dB minimum of noise pulse suppression, with adjustable blanking level and widths. I notice the K3 has these features, but it still does not seem to reduce impulse noise more than an S unit or two (6-12 dB), which is inadequate. I do not use blankers here myself; my entire station is homebrew and the receiver is a phasing, image cancelling job with no blanking at all, (or AGC for that matter). I get along fine with neither, even in contests." ****************************************************************************************** Eric-WA6HHQ & Co. + All the loyal "K3ers" WHADDAHYA THINK??? Jim/nn6ee ______________________________________________________________ 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 ______________________________________________________________ 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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In reply to this post by JIM DAVIS-11
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In reply to this post by JIM DAVIS-11
The problem with a second receiver tuned (significantly, like Collins) out of band is that the noise isn't always the same at the two frequencies.
IMHO, the problem with most blankers, as mentioned below, is that the designers don't introduce any delay in the signal path. It takes some time to amplify, detect and form the blanking pulses that drive the noise gate. Absent delay, the noise pulses get through the gate and do their mischief before the blanking takes place. See: http://k6mhe.com/n7ws/Noise_Blanker.pdf Wes N7WS --- On Fri, 8/7/09, JIM DAVIS <[hidden email]> wrote: > From: JIM DAVIS <[hidden email]> > Subject: [Elecraft] Subject: "Another Better Mouse-trap?" > To: [hidden email] > Date: Friday, August 7, 2009, 2:42 PM > > This idea was put forth by "Don-W6JL" (Fallbrook, CA)!!! > > His quote: " I have tested many "noise blankers" in > modern rigs, on the air. Both the I.F. noise > gates and the DSP-based “noise reducers”. Not one > works the way I feel it should. I think you > need a separate noise receiver, independent of the main > receiver, and tuned to a frequency that is > outside of a ham band. (There have been excellent > homebrew receivers using this approach for > noise blanking). This then drives the noise gate, and > is timed so that it gates the I.F before > the noise pulse arrives there. A good blanker should > have 40 dB minimum of noise pulse > suppression, with adjustable blanking level and > widths. I notice the K3 has these features, but > it still does not seem to reduce impulse noise more than an > S unit or two (6-12 dB), which is > inadequate. I do not use blankers here myself; my > entire station is homebrew and the receiver is > a phasing, image cancelling job with no blanking at all, > (or AGC for that matter). I get along > fine with neither, even in contests." > ______________________________________________________________ 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 |
Re: Subject: "Another Better Mouse-trap?"
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Wes Stewart wrote:
> > IMHO, the problem with most blankers, as mentioned below, is that the > designers don't introduce any delay in the signal path. It takes some + time to amplify, detect and form the blanking pulses that drive the + noise gate. The standard analogue noise blanker achieves this by using a wideband, and therefore low group delay, detector for the noise pulses, and then gating the signal after the main selectivity filters, with their relatively large group delay. > -- David Woolley "we do not overly restrict the subject matter on the list, and we encourage postings on a wide range of amateur radio related topics" List Guidelines <http://www.elecraft.com/elecraft_list_guidelines.htm> ______________________________________________________________ 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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