On Saturday, May 31, 2014 11:05:34 AM UTC-4, haitic...@gmail.com wrote:   
   > FIX CR's   
   >   
   >   
   >   
   > Suppose we have two channels, a + B, which are neighboring wavelengths in   
   > spectrum. Suppose there is a signal buried down in channel B but not in A   
   > Say the signal is 1/1000 the strength of A-B.   
   >   
   Are you assuming that the noise in A is the same, (correlated) with that in B?   
   In general that is not the case.  (maybe only when the source is laser noise?)   
      
   There are some neat tricks to get rid of uncorrelated noise in two channels.   
   (But this assumes there is also a signal in both channels.)   
   So imagine two opamps looking at the jonhson noise of a single resistor.   
   If those tow signals are multiplied together then the uncorrelated opamp noise   
   goes away (in time) and the correlated johnson noise in each channel remains.   
      
   George H.   
   >   
   > So we just add the signals in A,B 10,000 times. Then the buried differential   
   >   
   > signal in B can rise above the concomitant noise in A,B. We see the signal   
   by subtracting the value in A.   
   >   
   >   
   >   
   > The question is, can this work under some circumstances? Can it work as a   
   blind   
   >   
   > heuristic where we don't know where a signal is, nor where A,B are? This can   
   be   
   >   
   > run in  "supervised" pattern recognition mode, where we are looking for   
   >   
   > correlations to some external thing. It could also be run in "unsupervised"   
   >   
   > PR mode, where a signal emerges by itself, and you say "this is interesting.   
   >   
   > It might mean something."   
   >   
   > >   
   >   
   > > "If you subtract the killings, DC has one of the lowest crime rates in the   
   >   
   > >   
   >   
   > >  country." - Mayor Berry, DC.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)