[evlatests] L-Band data -- Origin of yesterday's reported closure errors identified ...

[Michael Rupen]

>    Frequencies appear to be correct.

Excellent.

>    25R and 26L give perfect (integer) zero amplitudes.

Th Station Boards are claiming all data are invalid for those IFs.

For ea25-A this comes from CRC errors on input C from the deformatter.

For ea26-C the origin is not so obvious, but again the data (in)valid bit
   is being set at the Delay Modules.

>    6, 15, and 20 give only noise on both polarizations

ea06 and ea20 have no L band receivers.

ea15 had some circuit fault I believe.

>    26R and 27L give only noise.

ea26-A is mysterious -- the deformatter fibers were misaligned, but that
   should just give odd data as seen at C band.

ea27-C's deformatter is either missing or brain-dead.

>    Delays are HUGE = +/- 200 nsec.  Indeed, with the relatively coarse
> frequency resolution (1 MHz), the phase gradient across the channel
> width (0.45 turns in the worse case!) is sufficient to explain the
> 'closure' errors I reported on yesterday.

Oh good!  I started wondering about that just when this e-mail arrived :)

               Michael