Auto Notch on CW?
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Is there a reason why the auto-notch has to be disabled on CW?
There are many times when it is highly desirable to notch strong CW signals or carriers whilst trying to listen to a weaker DX signal underneath, but usually at a different pitch. My previous rig, a Ten-Tec Jupiter, was highly effective on CW in pile-ups with the auto-notch enabled & could cope very well with the policeman & jammers on the DX frequency, allowing the weaker signal to be copied underneath. Manual notch is too fiddly in this case when most of the effort needs to be focused on finding the DX's listening frequency. A simple click on / click off of the auto-notch can work wonders in reducing strong QRM on the DX frequency. If it is possible to enable auto-notch on CW, please can it be done? It's not as stupid as it first sounds! 73 Ian G4FSU _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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Ian, I have a ICOM PRO II that has this feature as well. ICOM did not have "AUTO" notch on CW either because the "auto" could notch out the CW you are receiving. THe PRO II goes to "manual" for notching on CW, but is in "Auto" for SSB. I think the algorithm changes between modes because of the inherent differences. The notch is looking for a "tone" on SSB to deal with while on CW it does not know which "tone" to notch...thus....manual mode only. A real brain has to make the determination of which tone to notch. Lee K0WA In our day and age it seems that Common Sense is in short supply. If you don't have any Common Sense - get some Common Sense and use it. If you can't find any Common Sense, ask for help from somebody who has some Common Sense. Is Common Sense divine? _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Ian Greenshields
Many thanks to all who contacted me off-list. As most messages referred to
the same issue, I thought I'd try and explain better why I think auto-notch on CW can be a useful QRM fighting tool. The obvious reason for not having auto-notch on CW is either that it notches out the signal you are trying to listen to, or that it cannot differentiate between multiple wanted and unwanted signals. The secret is not to put too much thought or intelligence into it. The auto-notch should simply go for the strongest signal in the pass band; if it can also go for the second strongest, or equally strong, so much the better, but it doesn't matter if it can't, it will still have cut the QRM by at least 50%. The real situation in a DX pile-up is wanted DX signal is almost never the strongest signal (if it is - work it & move on - no problem!). It's the errant callers & tuner uppers (accidental or otherwise) and up up up police that cause the problem. An auto-notch that can take these out, even one at a time, is a great help & the stronger the signal, the easier it is for the auto-notch to hit & track it. And, by definition, it hits the biggest problem first. It needs a simple tap on, tap off access, as it needs to be disabled quickly if the frequency becomes clear. The Jupiter auto-notch is effective in not being very effective as it doesn't work on weak signals (good!) & just sits on the biggest signal it finds in the pass band (also good). Of course, if the interfering signal is exactly co-frequency, it'll kill the DX too, but this rarely happens as the human ear is very good at separating even a few 10s of Hz. If the frequency is completely jammed, it won't help either. I strongly believe the best filters & decoders are between our ears; an auto-notch that cuts down the biggest signal whilst letting the brain concentrate on the weaker DX underneath can be the difference between a QSO & a bust call. Worked VP6DX this week for an all-time new one, and K3 to K3! When the Eu. idiot brigade started up on 40M, I instinctively tried to engage the auto-notch & was surprised to find it not there. Am I the only person transitioning from a Ten-Tec radio to miss it? 73 Ian G4FSU _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Ian Greenshields
Ian Greenshields wrote: >Is there a reason why the auto-notch has to be disabled on CW? Already answered (i.e. sometimes it could eliminate the desired signal!) >There are many times when it is highly desirable to notch strong CW signals or carriers whilst trying to listen to a weaker DX signal underneath, but usually at a different pitch. The problem is that the K3's Manual Notch is relatively wide. An interfering signal must be >100 Hz away before Notch doesn't attenuate the desired signal (this per some plots N1EU sent me). For this reason, you're much better off using narrow DSP Width (<200 Hz) which is also easier to set up quickly versus the Manual Notch. Another option is to use PBT to shift the DSP filter to eliminate the interfering signal. BTW Orion even has a much narrower Notch than the K3 but I seldom used it instead of simply narrowing DSP Width. 73, Bill W4ZV |
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I agree Bill, using a narrower DSP width or shifting the PBT is what I use
to push out an offending CW signal. I do use the notch filter (manual) when I want to listen to CW with a wider DSP filter and eliminate a BC carrier. I find that it works great in that situation. I usually work the novice ends of the CW segments, and there aren't as many CW sigs out there to contend with, but the BC stations pop in and out at different times of the day. Most of the time, I like to listen with a wider filter setting and notching out the BC carriers works really well for me, YMMV. With close in CW signals, pulling the DSP filter in and/or shifting the PBT usually works well for me even with sigs only a couple of hundred Hz away. At this point, I am no contester - only a casual op, so again, YMMV. 73, Dave W8FGU > > Ian Greenshields wrote: > > >Is there a reason why the auto-notch has to be disabled on CW? > > Already answered (i.e. sometimes it could eliminate the desired signal!) > > >There are many times when it is highly desirable to notch strong CW > signals or carriers whilst trying to listen to a weaker DX signal > underneath, but usually at a different pitch. > > The problem is that the K3's Manual Notch is relatively wide. An > interfering signal must be >100 Hz away before Notch doesn't attenuate the > desired signal (this per some plots N1EU sent me). For this reason, > you're > much better off using narrow DSP Width (<200 Hz) which is also easier to > set > up quickly versus the Manual Notch. Another option is to use PBT to shift > the DSP filter to eliminate the interfering signal. BTW Orion even has a > much narrower Notch than the K3 but I seldom used it instead of simply > narrowing DSP Width. > > 73, Bill W4ZV > > _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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This just got me thinking... Wouldn't it be possible write instructions to
the auto notch to stay away from a signal right in the centre of the pass band. It just have to read the pitch setting and don't notch signals there. At least that would help to remove some of the sporadic tuners that never bothers to listen. All the operator has to do is to make sure to zero beat the other station. I am no programmer, but has this option been considered before? 73 de Björn /SM0MDG _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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Seems like a good programming problem.... I am not a programmer either, or a very sloppy one....I hack at programming
The question I have is....what is zero beat? Yes, I know what the term means, but I find myself not being zero beat by ear because of impaired hearing. I like to listen low pitches where my hearing is better than to higher pitches where my hearing rolls off quickly. I have problems finding zero beat because of my hearing. Even in contest, you had better keep the RIT on because a lot of operators don't get near zero beat when I am running QSOs. So, zero beat is somewhat relative to the operator. In the truest sense...zero beat is when you are on the same frequency...but that is hard to do for some hearing impaired or tone deaf operators. I am looing forward to the equalizer in the K3.... Lee - K0WA In our day and age it seems that Common Sense is in short supply. If you don't have any Common Sense - get some Common Sense and use it. If you can't find any Common Sense, ask for help from somebody who has some Common Sense. Is Common Sense divine? _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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On 080222 18:43 , "Lee Buller" <[hidden email]> wrote:
> In the truest sense...zero beat is when you are on the same frequency...but > that is hard to do for some hearing impaired or tone deaf operators. Lee, Zero beat would be considered to be whatever side tone pitch value you have set. Then it is up to the operator to tune accordingly, and the K3 has an "auto spot" feature that does a pretty good job zero beating automatically. In theory it makes sense to me, but I have no clue what would be involved to make it work. 73 de Björn /SM0MDG _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Bjorn
On Fri, 2008-02-22 at 09:30, Björn Mohr wrote:
> This just got me thinking... Wouldn't it be possible write instructions to > the auto notch to stay away from a signal right in the centre of the pass > band. It just have to read the pitch setting and don't notch signals there. > At least that would help to remove some of the sporadic tuners that never > bothers to listen. All the operator has to do is to make sure to zero beat > the other station. I am no programmer, but has this option been considered > before? I believe the LMS (least-mean square) algorithm used for autonotch automatically notches all CW signals. It would probably be quite difficult to modify it to treat some frequencies differently than others. > In theory it makes sense to me, but I have no clue what would be involved to > make it work. Probably the way to do it is to (1) process the input signal using the standard LMS algorithm, (2) also process the input signal with a narrow band-pass filter tuned to the center of the passband, and then (3) combine the output of the two processes. It seems like that should work and wouldn't be too hard to implement. Al N1AL _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Bjorn
How to adjust the Notch on Manual.... What knob works, etc.????????????? 73Charles Harpole [hidden email] _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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