[K3] Noise Reduction Recording
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I'm still having trouble determining if what I hear is noise that NB should
get rid of. This is because I'm a relatively new Ham without the experience to know what I'm hearing. So I have made a recording on the noise and it is available from <http://homepage.mac.com/davidferrington/FileSharing2.html> I have recorded 3.740MHz in 5 second tracks with a tone between each change of NR setting, viz: 5 seconds of no NR, 200mS tone @ 700Hz 5 seconds of NR F1-1, 100mS tone at 1400Hz 5 seconds of NR F1-2, 100mS tone at 1400Hz 5 seconds of NR F1-3, 100mS tone at 1400Hz 5 seconds of NR F1-4, 200mS tone at 700Hz 5 seconds of NR F2-1, 100mS tone at 1400Hz etc. I have found no NB setting that affects this, I can possibly hear a very slight change, but it does not cancel the noise. I can do the same for the NB settings if people wish. I would appreciate some feedback on this please, is this just broadband hash in my urban neighbourhood from er, broadband and wall warts etc? Mail me off list if you'd like me to mail you a copy of the file direct. 73 de M0XDF / K3 #174 -- Why should I fear death? If I am, death is not. If death is, I am not. Why should I fear that which cannot exist when I do? -Epicurus, philosopher (c. 341-270 BCE) _______________________________________________ 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 |
Re: [K3] Noise Reduction Recording
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> is this just broadband hash
>in my urban neighbourhood from er, broadband and wall warts etc? Yes, also known as frying bacon/eggs, atmospheric qrn, call it what you will. The cure is a separate receiving antenna. For a fairly convincing demonstration of the Wellbrook 1530 loop in action on 160 listen to this http://www.wellbrook.uk.com/G0BDE/ Personally I have never found any NR implementation (from any manufacturer) to be very effective on audio signals and completely agree with Shaun's comment >one of the things with noise >reduction I've found is that it tends to detract some from the original >quality of the audio you're trying to weed out from all that noise as >well and in many cases, apply too much and everything's in the mud. >audio and all. What you really need is a method of identifying the actual ssb speech waveform, extracting the noise from it leaving the signal in the clear. There is a company in Germany that produces an outboard unit that I find very effective without the degradation in the audio. Audio demo here http://www.home.vrweb.de/michels/sound_demo.htm I use a pair of their DX-21 kit modules and feed the left/right stereo output into each one so I get independent NR control of each channel. There is an Eham review here http://www.eham.net/reviews/review/43017 By using a pair I also retain the audio fx and binaural I-Q. You would need to contact the company about the availability of the DX21 modules as I see they are no longer shown on the site. I find the combination of a receiving antenna (I use a rotatable 1530 loop) and the outboard noise reduction very effective on 80/160 grey line SSB weak signal work for instance. Anyway, something to think about. 73 to all Trevor G0KTN _______________________________________________ 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 |
Re: [K3] Noise Reduction Recording
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In reply to this post by M0XDF
Hi David:
I hear NO NOISE (at all) on any of your recordings! Well... what 'noise' I do hear is (to me anyway) 'band noise'... atmospheric noise and not electro-mechanical noises such as would normally be classified as 'line noise' or man-made. This actually a pretty good demonstration is a nice, CLEAR 75-meter band... I certainly wish I had MY 80/75 m band noise to be THAT low level all of the time. The BACKGROUND (band noise) which you hear on this band is NORMAL and should not be considered to be unusual. And there is NO noise blanker of which I am aware that will remove what you recorded. However, enabling the [NR], Noise Reduction feature of the K3 will help to significantly REDUCE the level of the background noise, albeit lending a slightly 'watery' sound to the real received signal... we seldom get something for nothing these days. 73, Tom Hammond N0SS At 02:47 02/25/2008, David Ferrington, M0XDF wrote: >I'm still having trouble determining if what I hear is noise that NB should >get rid of. This is because I'm a relatively new Ham without the experience >to know what I'm hearing. > >So I have made a recording on the noise and it is available from ><http://homepage.mac.com/davidferrington/FileSharing2.html> > >I have recorded 3.740MHz in 5 second tracks with a tone between each change >of NR setting, viz: > 5 seconds of no NR, 200mS tone @ 700Hz > 5 seconds of NR F1-1, 100mS tone at 1400Hz > 5 seconds of NR F1-2, 100mS tone at 1400Hz > 5 seconds of NR F1-3, 100mS tone at 1400Hz > 5 seconds of NR F1-4, 200mS tone at 700Hz > 5 seconds of NR F2-1, 100mS tone at 1400Hz > etc. > >I have found no NB setting that affects this, I can possibly hear a very >slight change, but it does not cancel the noise. >I can do the same for the NB settings if people wish. > >I would appreciate some feedback on this please, is this just broadband hash >in my urban neighbourhood from er, broadband and wall warts etc? > >Mail me off list if you'd like me to mail you a copy of the file direct. > >73 de M0XDF / K3 #174 > >-- >Why should I fear death? If I am, death is not. If death is, I am not. Why >should I fear that which cannot exist when I do? >-Epicurus, philosopher (c. 341-270 BCE) > > >_______________________________________________ >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 _______________________________________________ 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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Yes thanks Tom, a lot of people have said that its not that bad - I guess I
want it to be silent when there isn't anyone on the other end :) I found some real noise on 6m and the NB cut that out a treat, so alls well. On 25/02/2008 14:56, "Tom Hammond" <[hidden email]> sent: > Hi David: > > I hear NO NOISE (at all) on any of your recordings! > > Well... what 'noise' I do hear is (to me anyway) 'band noise'... atmospheric > noise and not electro-mechanical noises such as would normally be classified > as 'line noise' or man-made. This actually a pretty good demonstration is a > nice, CLEAR 75-meter band... I certainly wish I had MY 80/75 m band noise to > be THAT low level all of the time. > > The BACKGROUND (band noise) which you hear on this band is NORMAL and should > not be considered to be unusual. And there is NO noise blanker of which I am > aware that will remove what you recorded. However, enabling the [NR], Noise > Reduction feature of the K3 will help to significantly REDUCE the level of > the background noise, albeit lending a slightly 'watery' sound to the real > received signal... we seldom get something for nothing these days. > > 73, > > Tom Hammond N0SS > > At 02:47 02/25/2008, David Ferrington, M0XDF wrote: >> I'm still having trouble determining if what I hear is noise that NB should >> get rid of. This is because I'm a relatively new Ham without the experience >> to know what I'm hearing. >> >> So I have made a recording on the noise and it is available from >> <http://homepage.mac.com/davidferrington/FileSharing2.html> >> >> I have recorded 3.740MHz in 5 second tracks with a tone between each change >> of NR setting, viz: >> 5 seconds of no NR, 200mS tone @ 700Hz >> 5 seconds of NR F1-1, 100mS tone at 1400Hz >> 5 seconds of NR F1-2, 100mS tone at 1400Hz >> 5 seconds of NR F1-3, 100mS tone at 1400Hz >> 5 seconds of NR F1-4, 200mS tone at 700Hz >> 5 seconds of NR F2-1, 100mS tone at 1400Hz >> etc. >> >> I have found no NB setting that affects this, I can possibly hear a very >> slight change, but it does not cancel the noise. >> I can do the same for the NB settings if people wish. >> >> I would appreciate some feedback on this please, is this just broadband hash >> in my urban neighbourhood from er, broadband and wall warts etc? >> >> Mail me off list if you'd like me to mail you a copy of the file direct. >> >> 73 de M0XDF / K3 #174 >> >> -- >> Why should I fear death? If I am, death is not. If death is, I am not. Why >> should I fear that which cannot exist when I do? >> -Epicurus, philosopher (c. 341-270 BCE) >> >> >> _______________________________________________ >> 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 > > _______________________________________________ > 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 -- It is unwise to be too sure of one's own wisdom. It is healthy to be reminded that the strongest might weaken and the wisest might err. -Mohandas K. Gandhi (1869-1948) _______________________________________________ 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 |
Re: [K3] Noise Reduction Recording
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In reply to this post by Trevor Smithers
Trevor Smithers <[hidden email]> wrote on Monday, February 25, 2008 at
1:51 PM: > What you really need is a method of identifying the actual ssb speech > waveform, extracting the noise > from it leaving the signal in the clear. There is a company in Germany > that produces an outboard unit > that I find very effective without the degradation in the audio. Audio > demo here > http://www.home.vrweb.de/michels/sound_demo.htm Thanks Trevor. 73, Geoff GM4ESD _______________________________________________ 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 M0XDF
SOunds like plain old "white noise" to me. I get plagued with the same
stuff during the day sometime. What is the difference in noise level with the antenna connected and disconnected? 73, Sandy W5TVW ----- Original Message ----- From: "David Ferrington, M0XDF" <[hidden email]> To: "Crafters" <[hidden email]> Sent: Monday, February 25, 2008 2:47 AM Subject: [Elecraft] [K3] Noise Reduction Recording > I'm still having trouble determining if what I hear is noise that NB > should > get rid of. This is because I'm a relatively new Ham without the > experience > to know what I'm hearing. > > So I have made a recording on the noise and it is available from > <http://homepage.mac.com/davidferrington/FileSharing2.html> > > I have recorded 3.740MHz in 5 second tracks with a tone between each > change > of NR setting, viz: > 5 seconds of no NR, 200mS tone @ 700Hz > 5 seconds of NR F1-1, 100mS tone at 1400Hz > 5 seconds of NR F1-2, 100mS tone at 1400Hz > 5 seconds of NR F1-3, 100mS tone at 1400Hz > 5 seconds of NR F1-4, 200mS tone at 700Hz > 5 seconds of NR F2-1, 100mS tone at 1400Hz > etc. > > I have found no NB setting that affects this, I can possibly hear a very > slight change, but it does not cancel the noise. > I can do the same for the NB settings if people wish. > > I would appreciate some feedback on this please, is this just broadband > hash > in my urban neighbourhood from er, broadband and wall warts etc? > > Mail me off list if you'd like me to mail you a copy of the file direct. > > 73 de M0XDF / K3 #174 > > -- > Why should I fear death? If I am, death is not. If death is, I am not. Why > should I fear that which cannot exist when I do? > -Epicurus, philosopher (c. 341-270 BCE) > > > _______________________________________________ > 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 > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.516 / Virus Database: 269.21.1/1297 - Release Date: 2/25/2008 > 9:22 AM > > _______________________________________________ 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 |
Re: [K3] Noise Reduction Recording
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In reply to this post by Trevor Smithers
Here's another system:
http://radio.bhinstrumentation.co.uk/html/sound_file_demonstration.html David G3UNA > > What you really need is a method of identifying the actual ssb speech > waveform, extracting the noise > from it leaving the signal in the clear. There is a company in Germany > that produces an outboard unit > that I find very effective without the degradation in the audio. Audio > demo here > http://www.home.vrweb.de/michels/sound_demo.htm > > I use a pair of their DX-21 kit modules and feed the left/right stereo > output into each one so I get > independent NR control of each channel. > There is an Eham review here http://www.eham.net/reviews/review/43017 > > By using a pair I also retain the audio fx and binaural I-Q. > You would need to contact the company about the availability of the DX21 > modules as I see they are no > longer shown on the site. > > I find the combination of a receiving antenna (I use a rotatable 1530 > loop) and the outboard noise > reduction very effective on 80/160 grey line SSB weak signal work for > instance. > > Anyway, something to think about. > > 73 to all > Trevor G0KTN > > > 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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the BHI product is sold in the states by GAP....
it does work better( my opinion) than the "clearspeech" product. Hope I'll be able to determine someday that the K3 is/will be as effective.... haven't been able to compare the two. YET. bill At 12:20 PM 2/25/2008, David Cutter wrote: >Here's another system: > >http://radio.bhinstrumentation.co.uk/html/sound_file_demonstration.html > >David >G3U _______________________________________________ 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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That product does work well. But then I'm biased...
73 Stewart G3RXQ On Mon, 25 Feb 2008 14:51:41 -0600, Bill NY9H wrote: > the BHI product is sold in the states by GAP.... > it does work better( my opinion) than the "clearspeech" product. > > Hope I'll be able to determine someday that the K3 is/will be as effective.... > haven't been able to compare the two. YET. > > bill > > At 12:20 PM 2/25/2008, David Cutter wrote: >> Here's another system: >> >> http://radio.bhinstrumentation.co.uk/html/sound_file_demonstration .html >> >> David >> G3U >> > _______________________________________________ > 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 _______________________________________________ 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 |
Re: [K3] Noise Reduction Recording
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In reply to this post by Trevor Smithers
Trevor Smithers wrote:
> > What you really need is a method of identifying the actual ssb speech waveform, extracting the noise More or less by definition, if you have mix of an unknown signal and noise, you cannot separate the two. That's because noise is random and therefore unpredictable and the signal is unknown, so also unpredictable. To remove some of the noise, you must make assumptions about the signal. For speech, that probably means assuming that only discrete formant frequencies are present (but that isn't valid for unvoiced sounds and particularly for s and h sounds - the loss of these may be why people find noise reduced signals to be muddy), identify those frequencies, and then attenuate all the other frequencies. If the signal is close to the noise, you will not be able to identify the important frequencies properly, and therefore not be able reduce the noise this way. More drastically, you can try and construct a set of voice tract model parameters, and then synthesize the speech from those (this is what GSM does, but for bandwidth reduction rather than noise reduction, so it assumes a reasonable starting SNR). Most drastically, you use speech recognition and have the noise reducer re-speak the words. Currently the best tool for doing speech recognition in the presence of noise is the human brain, though, so the best way of getting noise reduction is to get someone else to listen to the signal and repeat it to you! Generally, noise reduction has to be more of an operator comfort thing than really improving the signal. If the noise is so strong that you cannot make out the speech, the noise reduction isn't going to be able to find it anyway. -- David Woolley Emails are not formal business letters, whatever businesses may want. RFC1855 says there should be an address here, but, in a world of spam, that is no longer good advice, as archive address hiding may not work. _______________________________________________ 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 |
Re: [K3] Noise Reduction Recording
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In reply to this post by Trevor Smithers
Trevor Smithers wrote:
> What you really need is a method of identifying the actual ssb speech waveform, extracting the noise > from it leaving the signal in the clear. There is a company in Germany that produces an outboard unit > that I find very effective without the degradation in the audio. Audio demo here > http://www.home.vrweb.de/michels/sound_demo.htm The web site isn't exactly forthcoming about how it really works, even though they claim to have a patent (personally I think patents go against the spirit of ham radio). Lingua suggests a voice tract model, but the talk of envelopes doesn't seem consistent with that. Incidentally, MP3 is not a good format for representing noisy signals. The compression algorithm assumes that the signal has strong spectral peaks which greatly exceed the noise. It actually suppresses parts of the spectrum, where it thinks the sound is dominated by adjacent spectral peaks. In general, noisy signals are difficult to compress. Sound will show a bias towards zero, so will be partially comprssible. > -- David Woolley Emails are not formal business letters, whatever businesses may want. RFC1855 says there should be an address here, but, in a world of spam, that is no longer good advice, as archive address hiding may not work. _______________________________________________ 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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