[evlatests] Some other curiosities

Rick Perley rperley at nrao.edu
Tue Oct 9 18:57:31 EDT 2007


       The aliasing tests I reported on were in fact made at a variety 
of bandwidths -- 12.5, 6.25, 3.125, 1.56, and 0.78 MHz.  For three of 
these bandwidths, the data looked completely normal (other than the 
aliasing, just noted).   For the other two, two worrisome problems were 
seen. 

    a) All was normal at 12.5, 3.125, and 0.78 MHz bandwidths. 

    b) At 6.25 MHz bandwidth, a 'global' delay error between the EVLA 
and VLA of 200 nsec (exactly!) was seen.  This is easily visible in all 
the bandpass spectra. 

    c) At 1.56 MHz bandwidth, the EVLA and VLA were completely incoherent! 

 



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