[evlatests] RFI Report -- 0.95 -- 18 GHz

[Rick Perley]

    The wideband tests noted earlier covered the entire band from 900 
through 18000 MHz.  I've reviewed all of the spectra for RFI, and can 
offer the following, semi-complete summary.  Note that the spectral 
resolution is 2 MHz, so sensitivity to narrow-band RFI is not great.  
Also, with the modest fringe-wrapping, the high frequency observations 
are fairly immune to external interference. 

    L-Band. 

    By far the strongest are in the 1520 through 1632 MHz regions.
    Specific frequencies:
   
    954, 974 -- 988, 998 -- 1004
    1025 -- 1150 (this is the DME zone)
    1200
    1216 -- 1252
    1228
    Pulsed signals at 1254, 1338, 1310, 1330 MHz (all radars)
    1522 -- 1560
    1572 -- 1578
    1598 -- 1606
    1618 -- 1632
    1672 -- 1694
    1932 -- 1942
    1980 -- 1986

    S-Band:

    Almost every harmonic of 128 MHz is seen, but the odd numbered ones 
are worst. 
    plus:
    2104
    2184 -- 2202
    2320 -- 2350 (satellite radio)
    2396 -- 2404
    3626
    3700 -- 4000 (satellite downlinks -- seen only on the shortest 
baselines). 

    C-Band:

    Nothing new here -- the following recaps what has been reported before:

    4000 -- 4200 (satellite downlinks, only visible on short baselines)
    5988 -- 6018 (microwave link)
    6242 -- 6270 (microwave link)
    6568 -- 6582 (microwave link)
    6770 -- 6778 (microwave link?)
    7030 (weak)

    X-Band:

    Strong *internal* birdie seen at 8192 MHz on all baselines common to 
antenna 16:  This antenna is radiating strongly!!  The birdie is seen 
weakly on a few other baselines, likely due to common coupling from 16. 
    9344 (pulsed, but weak).

    Ku-Band:

    The expected satellite downlinks are seen, but remarkably weak:  
mostly between 12.21 through 12.69 GHz.
Some baselines show a wide range of signals:  11.9 through 12.7 GHz.  
The RFI is weaker than feared, likely due to a combination of pointing 
to the NW, and significant phase rotation. 

    That's ALL!