[Elecraft] RF Noise canceller ?

[Marinos Markomanolakis, M.D.]

Hi Peter,
Would this type of noise canceler not work on "white" noise also ?
73,
Marinos, ki4gin

>From: "Peter Zenker" <DL2FI at qrpproject.de>
>To: "'Marinos Markomanolakis, M.D.'" 
><sv9dru at hotmail.com>,<elecraft at mailman.qth.net>
>Subject: RE: [Elecraft] RF Noise canceller ?
>Date: Sun, 3 Apr 2005 13:03:51 +0200
>
>Hello Marinos,
>
>There have been several schematics using such technics over the last 20
>years. Most of them use a seperate short antenna, feeding the signal pase
>shifted into  a combiner which combines the main Antenna Signal with the
>phases shifted extra antenna signal. This construction can reduce a lot of
>man made noise.
>I remember there was a commercial available stand alone unit sold by a 
>small
>english company.
>I myself built such a unit to help reducing my noise problem especialy at
>160m (I live in the middle of Berlin, Noise level in the evening is > S7)
>But I forgot the unit during the time because I do not have an 160m Antenna
>any longer.
>
>73 de Peter, DL2FI
>
> > -----Original Message-----
> > From: elecraft-bounces at mailman.qth.net
> > [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of
> > Marinos Markomanolakis, M.D.
> > Sent: Sunday, April 03, 2005 6:45 AM
> > To: elecraft at mailman.qth.net
> > Subject: [Elecraft] RF Noise canceller ?
> >
> > Just a question for the technically inclined group members:
> >
> > How feasible or worth the effort, would be the addition of an
> > option to the
> > K2 which would sample RF noise from a ferquency close to the used
> > band,(tunable?) which is devoid of signals, phase invert and
> > reinject the noise to an IF stage or even the antenna input
> > in order to cancel our the "white or pulse" noise components,
> > preserving the desired signal ?
> >
> > Why similar circuits are not preferred in HF receiver designs
> > instead of DSP filters ?
> >
> > Similar circuits are commonly used in biomedical devices
> > (called linear averagers if I am not mistaken) and are very
> > effective in isolating electric signals from a particular
> > organ eg Heart in EKG or brain area of interest in EEG,
> > filtering out the irrelevant noise from the muscle cells...
> >
> > Just some food for thought.
> >
> >
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