27mar13 spectral channel jumps (top)

• The file with the problem: p2787.20130327.B1726-00.b1s1g0.00200.fits
• The PFB overflows were reported in polB. Looking at the data, there were also jumps in polA (just not as large).
• The mock setup was
• 64 channels, full stokes, 256 usec sampling, using lbw.
  
• 170MHz clock with 85 MHz bandwidth (divide by 2 in the digital filter).
• When the digital filter is used (to reduce the bandwidth) we have gotten these jumps in the data with higher clock rates.
• The problem has to do with the digital filter. When the full bandwidth is used, the jumps never occur.

• top frame: PolA spectra
• each row had been offset by 8000 counts
• there are 3905 spectra in each row
• Bottom frame: PolB spectrra
• The jumps occurred more often in polB

• The bright dots are the jumps

28mar13: running the diagnostics:

    The rdComp diagnostic was run on 28mar13 (see test results) . This test:

• Uses digitally generated noise (in place of the A/D input). This data is the same in each spectrometer.
  
• For each box the signal is processed by the fpga code and then sent to the first spectrometer (pdevs1).
• Each sample from all the spectrometers is compared with the sample from the first spectrometer. If any data value does not match, then that data is flagged as an error.

• The test was run on all 14 spectrometers (group 0 and group 1).
• Clock rates of 172.032, 170.00, 165.00, and 160 MHz were used
• Intermittent  problems occurred at 172.032,170, and 165 MHz.
• 160 MHz never failed.
• many of the failures included the box :b1s1g0 that gave p2787 problems.
  

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