[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

RE: DSP noise reduction--now I'm confused



In the parlance of DSP communications engineers, the LMS or
Widrow algorithm for adaptive noise reduction and adaptive
interference cancellation (or adaptive notch) are different
algorithms.  They look a lot alike to the non-cognoscenti but
their effects are quite different.  One is trying to enhance
coherent energy (adaptive noise canceller), the very thing the
other is trying to remove.  Thus the subject for this thread,
DSP Noise reduction and the content of the messages are,
algorithmically speaking, confusing me.  In fact on  my
IC756-P-II, the buttons for these two functions (ANR and
NF,automatic and manual) are on opposite sides of the radio.
In fact, in the CW mode, the IC756-P-II will NOT OPERATE in
the automatic mode for notch filtering, only the manual mode
because it will notch the morse tones. The Widrow algorithm has
no method for distinguishing between good tones and bad tones.
The time constant or gain might make it work in Morse mode but it
will nevertheless depress the power in the Morse tone.  The
slower the Morse, the deeper the depression given a fixed adaptation
constant.

Bob, N4HY


-----Original Message-----
From: owner-AMSAT-BB@amsat.org [mailto:owner-AMSAT-BB@amsat.org]On
Behalf Of Jon Ogden
Sent: Thursday, February 20, 2003 12:15 AM
To: Scott Townley; amsat-bb@amsat.org
Subject: Re: [amsat-bb] DSP noise reduction--now I'm confused


on 2/19/03 10:26 PM, Scott Townley at nx7u@arrl.net wrote:

> OK, you ClearSpeech owners:
> Does the thing not work on CW?  (Meaning, not of use to CW operators?)
> I notice from comments etc. that it "automatically" nulls out tones...
> Thanks

Yes, it works on CW.

The notch is somewhat adaptive.  Meaning, it takes a few seconds before it
starts knocking out the tone.  If you key up and stay keyed for more than a
couple of seconds, it will take it out.  CW though, is a short tone, but
multiple short tones.  No problem.  It ignores them.

73,

Jon
NA9D
-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)

Citizen of the People's Democratic Republik of Illinois

Life Member: ARRL, NRA
Member:  AMSAT, DXCC

http://www.qsl.net/na9d   <- Updated on 1/22/03!!!

"A life lived in fear is a life half lived."


----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org


----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home