[evlatests] Autocorrelation Spectra -- no tones?

[Rick Perley]

    I looked at the autocorrelation spectra which came with last 
Thursday's wideband test.  We have data for all four antennas and both 
polarizations.  The test spans 2048 MHz, centered at 6500 MHz. 

    I was surprised to see that the only strong non-RFI 'tone' visible 
was in subband 10 for antenna 22R.  Weaker 'tones' are seen on some 
other antennas, but nothing like what we saw in the spectra taken 2 
weeks ago... 

     Although all subbands show plausible autocorrelation spectra, some 
are negative!  The features within the spectrum are normal, the the 
entire spectrum is depressed below zero -- an offset.  These are

    subband 2 on antenna 15R
    subband 11 on antenna 15L
    subbands 2 and 12 on antenna 22L
    subband 2 on antenna 28L. 

    Also for reference:  The three microwave link RFI bands are clearly 
seen at:

    5994 -- 6020 MHz
    6242 -- 6272 MHz
    6610 -- 6622 MHz

    The last one is *by far* the strongest.