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Author Topic: Unique Advanced Notch Filter Planned for Flex  (Read 6208 times)
K0OD
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Posts: 2557




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« on: July 23, 2011, 04:44:46 AM »

"TNF or Tracking Notch Filter is a future enhancement to PowerSDR of which an alpha preview was given at Dayton earlier this year.

It is the ability to manually notch offending narrow band signals by placing a notch filter on the signal, of which you determine the depth and width of the notch by interacting with the Panadapter. The notch, once placed on the Panadapter, will "track" so if you change frequencies, the notch filter follows the offending signal on the Panadapter. The notches can be "remembered" or made persistent between restarts of PowerSDR so if you have external environmental noise that is constant at a particular frequency, you can establish a "notch field" to eliminate the offending signals. The number of notches you can define is very large (I forget the exact number as it is still under development), but I believe you are limited to 8 TNFs within the receive passband.

Tim Ellison, W4TME
Internet Systems Admin. & Customer Support Engineer
FlexRadio Systems^(TM)"

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K0OD
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« Reply #1 on: July 23, 2011, 05:55:24 AM »

Stan: "In Flextalk the key word is always planned and future."

Tim broke that news yesterday on Flexedge and only in response to a question about it. First I've heard of a "Tracking Notch Filter."  Guess it was previewed in Dayton but it's a very pleasant surprise to the rest of us.

Tim's detailed description suggests that it may be released soon.

 
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KE5JPP
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« Reply #2 on: July 23, 2011, 06:11:21 AM »

"TNF or Tracking Notch Filter is a future enhancement to PowerSDR of which an alpha preview was given at Dayton earlier this year.

In Flextalk the key word is always planned and future.

 Wink Cheesy

Stan K9IUQ



If it is anything like noise reduction or automatic noise filter in PowerSDR, it will take them at least 7 years to make it work (if it ever does).  Roll Eyes Roll Eyes Roll Eyes

Gene
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K0OD
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« Reply #3 on: July 23, 2011, 09:43:47 AM »

Noise reduction and auto notch work beautifully. Really well. They were "turned off" in a few beta versions and that was months ago. 
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ZENKI
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Posts: 938




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« Reply #4 on: July 23, 2011, 08:06:01 PM »

What would be nice from Flexradio is  packaging a true Phase correlative  interferometer  into PowerSDR. There would also have to be some sort of calibration routine included.   The options could be from a simple 2,3 or even 4 antenna system. This system could be very useful for noise mitigation as well. Getting  rid of jammers and noise would be good thing!

A Small aperture DF array would be a useful thing on the ham bands since it  is not very insensitive to different types of signal modulation including burst and cw. 
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KE5JPP
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« Reply #5 on: July 24, 2011, 05:00:07 AM »

Noise reduction and auto notch work beautifully. Really well. They were "turned off" in a few beta versions and that was months ago.  

Quote
Noise reduction and auto notch work beautifully.
Brian, I meant to say the Flex Noise BLANKERS work beautifully on many types of noise. I believe they were turned off in some betas.

Totally agree about Noise Reduction. I never use it in my Flex. Never used NR in my old Timewave. I think they're all just marketing snake oil. NR changes the tone of the audio and gives it an annoying hollow sound. But it doesn't make the weakest DX signals more copyable.

No doubt DSP NR sells (or sold) radios and outboard DSP units. I knew one guy who must have bought every outboard NR unit that came along. They never lived up to the hype.

I think Flex's NR was inoperable in some betas.    

Ha Ha, now you are backpedaling.  It is clear you are talking out your you-know-what.  Roll Eyes

This is a prime example of how some Flexies will lie about anything concerning their beloved Flex Radios.

The noise blankers have always worked fine in PowerSDR.

Gene
« Last Edit: July 24, 2011, 05:06:26 AM by KE5JPP » Logged
K0OD
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Posts: 2557




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« Reply #6 on: July 24, 2011, 06:06:43 AM »

Quote
This is a prime example of how some Flexies will lie about anything concerning their beloved Flex Radios. The noise blankers have always worked fine in PowerSDR.

Gene [who else?]


W6UV:  "I also verified that the NB actually does something useful now and ANF does as well."


KJ4SLP: "The noise reduction seems a bit better, the noise blanker still seems to do little, if anything."


Flexes own Bob McGwier in March: "The noiseblanker 1 and noise blanker 2 are also undergoing reconstruction.  Everything is being reworked and fine tuned for better performance."

--
February 2011: http://www.eham.net/ehamforum/smf/index.php?topic=73548.0

March 2011: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/2011-March/041917.html
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KE5JPP
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« Reply #7 on: July 24, 2011, 07:51:54 AM »

Quote
This is a prime example of how some Flexies will lie about anything concerning their beloved Flex Radios. The noise blankers have always worked fine in PowerSDR.

Gene [who else?]


W6UV:  "I also verified that the NB actually does something useful now and ANF does as well."


KJ4SLP: "The noise reduction seems a bit better, the noise blanker still seems to do little, if anything."


Flexes own Bob McGwier in March: "The noiseblanker 1 and noise blanker 2 are also undergoing reconstruction.  Everything is being reworked and fine tuned for better performance."

--
February 2011: http://www.eham.net/ehamforum/smf/index.php?topic=73548.0

March 2011: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/2011-March/041917.html

So what.  You were claiming the noise reduction and auto notch work beautifully.   Roll Eyes Roll Eyes Roll Eyes  Then you backpedaled by saying you meant the noise blankers not noise reduction.  Now you are saying the noise blankers don't work???

Sounds like nothing in PowerSDR works quite right.

Gene
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M0HCN
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Posts: 473




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« Reply #8 on: July 24, 2011, 09:01:09 AM »

Accepting that marketing is always a little hyperbole prone, I am not at all sure I see much advanced here.

You know the LO frequency so can trivially compute where in the IF any notches that may happen to fall within the passband need to be, then do the notches in the IF frequency domain, it is not like the code does not end up doing FFTs of the IF anyway, and the complex vector multiply is fairly cheap on modern processors.

I figure that the user interface would take considerably longer to code then the DSP (it almost always does).

What would be cool would be to use some phase binning techniques to improve sensitivity to periodic signals, lots of fun things you could do with that, the approach is documented in some of the radio astronomy papers (also in the civilian sonar literature). 

Regards, Dan.

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K0OD
Member

Posts: 2557




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« Reply #9 on: July 24, 2011, 09:33:19 AM »

KE5JPP: "So what. "
So predictable that response from you.

Flex NB works fine now but I'm sure you know that. Actually it's one of the features that Stan raved about... many PSDR versions ago when he owned one. 

See ya!
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WB6RQN
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Posts: 484




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« Reply #10 on: July 24, 2011, 08:11:39 PM »

Huh. Well, here is my take on these things in PowerSDR on my 1500, 3000, and 5000.

Noise Blanker: How well it works depends on the noise. On some noise (powerline noise I have to deal with) it produces about a 20dB reduction in noise. OTOH a really strong CW signal (local to me) will modulate other signals in the receiver's passband if the NB is on, which I find annoying. Regardless, it seems to work reasonable well over all.

Automatic Notch: It works fine if there is one carrier in the passband. I can't see anything wrong with it. But then, I almost never do SSB so I don't give it much chance to prove to me how good/bad it is.

Noise Reduction: It works ... I guess. It does improve the apparent S:N. I don't like the sound it imparts to the signal. I find that proper setting of the AGC threshold control does at least as much for reducing the apparent noise without the AGC pumping the noise and without the strange audio characteristic that the NR imparts to the signal. So, I just don't use it.

FM: it works well. I like it. I have gotten universally good reports, especially from people on simplex or listening to me on the repeater input. All this on 6m.

Advances Notch Filter: Haven't seen it, haven't heard it. Sounds like a really useful feature, much more useful than the ANF.

So there is what I consider to be an honest representation of my experience with the features of 2.1.5 without embellishment, whitewash, or trashing.

73 de Brian, WB6RQN/J79BPL


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W4HIJ
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Posts: 367




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« Reply #11 on: July 26, 2011, 05:46:51 PM »

The "tracking notch filter" was apparently shown at Dayton. That's when I first heard about it. Since then I have asked about it's status on a couple of different occasions and they are still working on refining it. I believe the response quoted from Tim was when someone asked what it was after I had inquired about it on the Flex reflector. I'm sure it will be included in PowerSDR software when they deem it ready. Of course you just can't please some folks no matter how hard you try. First they will complain that the software is not being released fast enough, then if you do release it before it's fully refined and tested, they will complain that it's buggy and unreliable. It's a no win situation for developers of any kind of software, not just Flex and radio related stuff. Actually, I've been quite happy with the speed of Flex software releases lately. After they got over the hump and quieted most of the  whining about CW issues, the software has been being updated on a pretty regular basis.
73,
Michael, W4HIJ
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