[Lowfer] Poor man's mw/lw wideband noise reduction

[Scott Tilley]

HI Paul

A method  used here done with a small 'noise' antenna and my LF 'sense' 
antenna and then mixing the two RF signals together produces excellent 
results and even allowed me to work the Yukon from within the City of 
Vancouver...  Normally a phase shifting network is used on the noise 
signal to allow one to first adjust the phase of the noise signal 180 
degrees of the received noise on the sense antenna.  Once you have 
adjusted the phase then the amplitude of the two RF signals is adjusted 
such that the offending signal is canceled.  This is really an iterative 
thing as each back and forth adjustment further improves the canceling. 

I use such a device on 2200m to deal with my one neighbour's light 
dimmer.   It also works (very well I might add) on any signals you 
receive on both antennas so it can be used to cancel local NDBs for 
example so you you can hear the DX ones on the same frequency... 

See here for a design I modified for 2200m.  It works well in the lowfer 
band to 600m as described...

http://users.tpg.com.au/users/ldbutler/LFNoiseCancel.htm

Also see
http://www.alg.myzen.co.uk/radio/136/pre_sel.htm

73 Scott
VE7TIL


PAUL DAULTON wrote:
>
> I found an article in Elektor magazine feb 2005, which can be 
> downloaded from Elektors's site, about
>
> a noise reduction method.
>
>  
>
> Basically two receivers are used.The loudspeaker outputs of the two 
> radios are connected in phase while
>
> the speaker in the second rec is disconnected. With the second 
> receiver tuned a little higher or lower than
>
> the main one the speaker of the main receiver is fed with the 
> difference between the two signals. External
>
> antennas should be connected in parallel. Using the volume adjustment 
> on the second radio a setting can be
>
> found that should result in a reduction of noise.
>
>  
>
> Sounds good I am trying to figure out how to apply to Argo connections.
>
>  
>
> Any comments?
>
>  
>
> Paul K5wms
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> >From the Lowfer mailing list
> Send messages to: Lowfer at mailman.qth.net
> To sub/unsub visit: http://mailman.qth.net/mailman/listinfo/lowfer
>