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Author Topic: Noise canceling speakers  (Read 579 times)
N5XO
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Posts: 104




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« on: February 04, 2010, 08:18:22 AM »

Has anyone tried the noise canceling speakers? Do they work, are they worth the extra cost?

Benefits and negatives?

I have a ham friend who is looking at different options to cleaning up noise issues and he asked me this today?

I have no experience with them so looking to see what I can learn about them.
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KAISERSOUSE
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Posts: 327


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« Reply #1 on: February 04, 2010, 08:21:15 AM »

I've been trying to figure out if I want the internal bhi DSP filter circuit installed in my DX-394....or if I should pay the extra $50 or so and get their speaker that has the DSP built in.

My thinking is that with the speaker, I can switch between radios (when I get off my ass and actually get my license) and have noise-filtering goodness all around.

Which speakers are you looking at? Are there alternatives to the slightly expensive external speaker I'm eye-balling?
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AE5NE
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Posts: 91




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« Reply #2 on: February 04, 2010, 10:18:16 AM »

What kind of noise issues?  If it's just crowded band conditions and you are not seeing AGC action or receiver desense from strong adjacent signals, the audio DSP might help.

On the other hand, if you are dealing with impulse noise, broad RFI, very loud close stations, etc..., then the filter pretty much needs to be at RF or IF stage.

If you can stand listening to the audio through the computer, there are programs such as http://mmhamsoft.amateur-radio.ca/pages/dsp-filter.php that will do audio passband filtering for you.
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AD4U
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Posts: 2157




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« Reply #3 on: February 04, 2010, 12:07:44 PM »

For the best results 99% of the time "man made noise" has to be located and cleaned up at its source.  I am sure some will disagree, but add on's such as noise cancelling speakers, DSP (at least what is available today), noise blankers, noise limiters, etc, are not worth the $$$.  There are even "tongue in cheek" ads touting SWR Spray, and I am sure somebody would buy it.

Bottom line is I would not WASTE my money.

Dick  AD4U
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AD4U
Member

Posts: 2157




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« Reply #4 on: February 04, 2010, 12:11:16 PM »

PS:  In my post I specifically mentioned "mad made noise".  Add static from thunder storms to the list of noise that cannot be effectively removed by "ad on's".

Dick  AD4U
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W5WSS
Member

Posts: 1688




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« Reply #5 on: February 04, 2010, 10:00:49 PM »

Hello Dick, I have become aware of a noise that "seems" to be common amongst many hams about the country. I do not have it recorded but beleive I heard the same sounding interference in different states of my amateur operation. Perhaps it is common to cable tv equipment as I am nearby some. It sweeps across the band/s is about 25khz wide back and forth sometimes stops sweeping but intensity remains. Have you heard anything similar?
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SCUBA
Member

Posts: 74




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« Reply #6 on: February 05, 2010, 04:54:20 AM »

Good morning,
If the noise is the constant, never changing, S-8 hiss on 20 meters, which message thread is the _basis_ for deciding whether or not to purchase a DSP noise inhibiting speaker or audio circuit?

Is it his message thread?
or is it this review:
http://www.eham.net/reviews/detail/6982
or this?
http://www.eham.net/reviews/detail/7500
or this?
http://www.eham.net/reviews/detail/3712
or the recorded demonstration on this website?
http://www.w4rt.com/
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K1BXI
Member

Posts: 812




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« Reply #7 on: February 05, 2010, 10:03:03 AM »

Dick..AD4U, I always thought the same as you until I tried a phasing type noise reduction unit. They really do work on local man made noise.

They do require a bit of work to get the sensing antenna to hear the same noise as your main antenna. But when that is accomplished, I have nulled S9+20db local noise completely away, without any signal loss of the station.

Not exactly a plug and play unit, but they will work.  

John
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AE5NE
Member

Posts: 91




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« Reply #8 on: February 05, 2010, 12:35:21 PM »

The nulling receiver isn't an audio-stage solution is it?
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AD4U
Member

Posts: 2157




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« Reply #9 on: February 05, 2010, 01:15:07 PM »

K1BXI - I guess we are never too old to learn something new.

Dick  AD4U
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K0CBA
Member

Posts: 298




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« Reply #10 on: February 05, 2010, 01:36:59 PM »

I entered this review a while back about the West Mountain Clear Speech speaker...perhaps it may give a point to ponder......

"I seem to have a lot of HF noise in my area so any little bit of noise relief is a Godsend and the Clear Speech is a most welcome addition.

The multi level processing settings and the much faster digital processing has made great improvements over the original Am-Com units...not that they wern't good, it's just that now I think the West Mountian design has made them great.

When using the maximum setting the digitized voice qualities and some of the holes in the audio as it processes out particuliarly strong noise spikes does take a bit of getting used to but under those severe conditions it's usually 'fair copy' vs 'no copy' so you are still ahead of the game.

There is no product nor device that is going to pull a S-1 signal out of 20 over 9 noise so don't expect miracles but for most day to day noise it earns it's keep. It's fantastic on my base station so I can only imagine how invaluable it would be in a mobile environment.

One thing I wish it had was a by pass for the audio...as it is now when the unit's power switch is OFF no audio is passed. Obviously there are times when it's not needed and unplugging the speaker from the rig's 'speaker output' is the only option. At some point I may add an audio by pass switch but for now it is not that big of a deal."
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K1BXI
Member

Posts: 812




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« Reply #11 on: February 06, 2010, 10:59:33 AM »

AE5NE said "The nulling receiver isn't an audio-stage solution is it?"

I'm not sure if you were asking me about nulling out the noise or not.

But if you were, No, it's done at RF, the actual signal from the antennas. The unit takes a local noise signal (one that has more of a pin point location) and compares it to the same noise signal that your main antenna is receiving and then phase shifts the noise signals 180 degrees apart causing the noise signal to cancel out before it reaches the input of your receiver.

Of course if you have more than one noise source at the same time, your out of luck as you can only phase shift one source at a time.

Nothing new about the concept, except it's easier to do at a lower cost with todays microprocessors. Do a Google search on "phase shift noise canceling" and you will find out more about it.

It's just another tool that will work for some and not for others.......The best way is still to stop the noise at it's source. Not always easy to do in todays noise environment.

John
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K1BXI
Member

Posts: 812




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« Reply #12 on: February 06, 2010, 11:07:44 AM »

Better to Google "antenna phase shift noise canceling"

John
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