Topband: noise

[W7lr at aol.com]

Noise is a frequent topband topic and consideration.  Here is a germ  on an 
idea - I dont know if new or already well known.  When I was in  Thailand in 
1964 (as HS1L) we had a research lab for Stanford Research  Institute.  Lots of 
communication research.  One project was recording  satellite Faraday rotation 
data.
The Bangkok noise and our ionospheric sounders made that difficult.   We had 
a good technician (engineer?), Bob Daniels (sk) - Fred K3ZO may remember  his 
W6 call, who built a noise reduction system.
I cant remember the details and wonder if topbanders might see if this  would 
work for topband.
 
We used two receivers, and used the IF outputs from those to drive a  
comparator.  In one input was N; and in the other input was S+N, and the  output was 
the difference or S.  We got good recordings and could not have  without that 
system.  It requires the same phase thru both paths for the  comparator to 
work.
 
I have two TS-850's, which have an 8.83 MHz IF output.  I wonder about  the 
comparator circuit and what circuitry to use beyond that, or whether to try  
and insert that back somewhere into the 850?
 
This system may be one used by Motorola in some of their equipment.   It 
requires finding a "clear" noise frequency near the desired signal  frequency.  It 
is a lot more effective than a noise blanker which tries to  blank out noise 
pulses.  
 
Thailand was fun - highlights were visiting the ancient jungle temples of  
Angkor Wat in Cambodia, and the annual elephant roundup in Thailand.   Pileups 
with HS1L were like those from VQ3,4,5 in 1948.
I enjoyed too the chance to help found RAST in Thailand.
 
Here's for low noise and lots of good signals in 2007.    73  Bob W7LR