spectral jumps at 2^n channels


  Spectral jumps have been seen at power of 2 channels previously. The jumps correlate with the input power levels. Higher input levels make the jumps go down. Not doing the first down shift in the butterfly stages also makes the jumps smaller.  They may be an underflow in the butterfly processing. Computing the rms values in counts when the jumps occur seems to leave values that should not be underflowing.

20may10: high res decimation test
23apr10: spectral jumps for adpwr=30,45,120 and pshift=0x1ff5, 0x0ff5.

08jul08: spectral jumps vs A/D and pshift levels.

23apr10: spectral jumps with noise source.

    Data was taken using the if2 noise source. The setup was:
The plots show the spectral jumps for this test (.ps) (.pdf):
processing: x101/100423/mockdlp.pro

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