[evlatests] WIDAR-0: phase jump is associated with slot location, not antenna

[Michael Rupen]

Kerry swapped the input fibers to antennas 25 and 28 yesterday, so we
could check whether the phase jumps track antennas or Station Boards
(presumably actually slot locations).

Before the swap, on 8jun09, we had the following groups of antennas which 
tracked one another but showed 180 degree phase jumps compared to the 
antennas in the other group:

   Group A:  ea01=r1s1 ea03=r2s3 ea23=r3s1           ea25=r2s1
   Group B:  ea02=r1s2 ea18=r3s0 ea19=r1s0 ea24=r2s2 ea28=r2s0

   [rXsY --> StB in rack X, slot Y]

i.e., the two groups correspond to the odd and the even StB slots.

After the swap, on 12jun09, I find the following:

   Group A:  ea01=r1s1 ea03=r2s3 ea23=r3s1           *ea28=r2s1*
   Group B:  ea02=r1s2 ea18=r3s0 ea19=r1s0 ea24=r2s2 *ea25=r2s0*

i.e., the phase jump tracks the slot number rather than the input antenna.

            -- Michael