[evlatests] L302 phase jumps

[Vivek Dhawan]

Here is a list of problem units from a test done July 31 evening.
I'm working to make the test ~10 minutes, we can run it often.

ea11  L302-3,  L302-4.                  ea12  L302-2.
ea15  L302-3.                           ea22  L302-1,  L302-4.
ea27  No L302 problems found. But there were delay jumps yesterday.
       This makes a differential phase jump on an IF pair (deltaA
       does not equal deltaC).  An LO jump makes identical phase
       changes on both of a pair.

I am pretty sure after talking to various engineers that this is the
'128MHz cable adjustment' problem, where the relative timing of the
128MHz and 20Hz edges changes with time or temperature. Sometimes it
is the 20Hz into the L302 which is weak or jittery. Both these things
should be checked.

I had a thought that it may be triggered by something else, but came
up empty on 2 counts:

1. No correlation with L302-x MIB versions (from Hichem.)

2. L305 modules are being deployed with updated FPGA firmware to change
    the DTS Timecode from 19.2 to 20 Hz. Below is the list from Leon, I
    see no correlation with antennas or dates of deployment.

    ea04 - no date recorded.               ea13 - 5/28/2014
    ea16 - <5/15/2014   ea14 - 6/11/2014   ea06 - 6/19/2014
    ea10 - 6/19/2014    ea12 - 7/2/2014    ea23 - 7/9/2014
    ea25 - 7/23/2014    ea05 - 7/10/2014
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