You need to pay this guy! K0CN

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Ok I hope FRS has Al K0CN on their payroll because his latest YouTube video is really awesome. I thought I knew what all the filters did and how to adjust them but after watching Al's video it now makes a lot more sense. So my tin foil hat is off to you Al. 73
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Rory - N6OIL

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Posted 2 years ago

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Rory - N6OIL

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Oh i almost forgot another ham I would like to mention is Ken NM9P for his great video on setting up mic profiles. 
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Paul

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Interesting thankyou. Although as a prospective buyer, I notice in the noise mitigation video that the ANF is discussed but no working example is shown. Do we infer from this that the issues from a few months ago have not yet been rectified?
(Edited)
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Ken - NM9P, Elmer

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Exactly!  The only thing better would be to have one or two tracking filters that can be set to automatically set to an offending carrier within the RX passband when a button is pushed, and delete themselves when the button is pushed again - the best of both worlds......Most of the offending carriers I have seen do not change rapidly enough to need a notch that automatically adjusts its frequency all the time.... just hit filter and it sets, semi-permanently, until cleared.....I would trade that for the ANF we have now in a heartbeat.

Ken - NM9P
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Paul

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Tim, thankyou for clarifying the operation of a TNF. I'm not trying to be obtuse, but two things occur to me:

1) curious use of the word 'tracking'. Isn't this simply what a plain old manual notch does? Adjust a control to null out a heterodyne and it stays there until re-adjusted or turned off. Surely 'tracking' implies the ability to follow something as it moves?

2) under what circumstances would one wish to notch out a carrier if it is outside the RX passband?
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Paul

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Ken, I agree that extra function would be very useful. The FTdx5000 digital notch filter works on multiple carriers within the RX passband and doesn't noticably distort the audio. It's so useful in fact, that I leave it switched in all the time and never need to use the manual notch. I am looking for an equivalent (or better ) system in my next radio - be that flex (or not).
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Tim - W4TME, Customer Experience Manager

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Paul,  you wrote...

 Isn't this simply what a plain old manual notch does? Adjust a control to null out a heterodyne and it stays there until re-adjusted or turned off. Surely 'tracking' implies the ability to follow something as it moves?

No.  Notch filters remove audio tones at a certain frequency.  If you have a notch filter defined on a legacy radio and change the frequency of the receiver, the tone changes frequency and the ANF has to retrain on the new frequency, so you hear the tone before the notch filter converges.  TFN remove the offending signal in the RF domain, not in the demodulated audio frequency (AF) domain, so when you change the frequency of the receiver, the notch filter "tracks" along and doesn't require retraining on the signal.  The other big difference is if you are listening to a weak signal and a S9+20 heterodyne shows up in your passband, that large signal, even after notched will capture the AGC and reduce gain, eliminating the weak signal.  Because TNF removes the offending RF from the demodulator before the signal in the RX passband is demodulated, the same S9+20 signal has no effect on the AGC.

2) under what circumstances would one wish to notch out a carrier if it is outside the RX passband?

I work 6m a lot.  At my QTH I have over 150 "carriers" from a plethora of RFI emitting devices around me from 50.0 through 50.300.  I use the TNF to notch out those offending signals and since most are permanent and do not change frequency, I make the TNFs persistent.  So when I tune through the 6m band, I am not constantly being bombarded with the annoying tones that change frequency as I sweep through the 6m band; I hear only signal.
(Edited)
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Paul

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Thanks for expanding on this Tim. I think I get the gist now. One last question, if I may:

The FTdx5000 manual notch operates at the IF. Am I correct in thinking that this is comparable then to a single TNF in terms of its resistance to the AGC being captured by a strong adjacent signal? I am able, for example, to notch out very large close-in PSK signals and still decode the much weaker wanted station.
(Edited)
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Kevin K4VD, Elroy

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Helpful video from Al. And Ken's videos on setting up great audio have been real helpful too.

Steve Ellington has some nice vids also. He has a detailed one for setting up AGC-T with a demo of what things sound like when it is set right: https://www.youtube.com/watch?v=Hwm6rszuMis&t=11s

K4DSP, Doug has a good one on setting up a VHF transverter. https://www.youtube.com/watch?v=w8JQ0SIUlI8

Maybe we need some Flex Webby awards complete with walks down the red carpet and the showing off of wardrobes. Well, maybe just the award.

Thanks to those that share.

73,
Kev K4VD
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Ken - NM9P, Elmer

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I was thinking about making a video tutorial about these exact controls. I guess I can mark it off my list. K0CN has done a better job than I would have done on this one! Well done!
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Steve W6SDM

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Rory, very nicely done.  That was easy to follow, even for me.  I haven't done a whole lot of experimenting with the various noise filters, but I will now.
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Dallas Ward

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Al's K0CN video on noise mitigation uses a red line to imply the Wideband noise control.  It would be wonderful if that red line is incorporated into the  SSDR package.  The guess work would be supplemented with a visual indication on where the level is set. Could it be turned on and off if possible?