[evlatests] Ku-Band Wideband Sensitivity

[Rick Perley]

    Last night's test run with the 3-bit system has been calibrated to 
show the antenna sensitivity.  It is very convenient to use the 
autocorrelation products for this -- fortunately, all are available for 
the 7 antennas now fully equipped. 

    Properly calibrated autocorrelations will give a good estimate of 
the antenna SEFD, in Jy.  Review of the data show:

    1) Most antennas are providing the expected sensitivity:  210 to 300 
Jy in SEFD.  (Unfortunately, we don't have a parallel 8-bit experiment 
to show the expected degradation). 

    2) The 'phenomenon' is easily seen on most antennas.  (This is the 
resonance that each sampler has).  As usual, it is time-variable (in 
frequency), and quite narrow -- a few channels.  It does not correlate 
between antennas, so is of minor consequence to most uses. 

    3) Some antenna/basebands have real problems.  Here is the list:

    ea05-D1:  The SEFD in this IF (baseband) is 400 to 1000 Jy, with an 
irregular variation with frequency. 
    ea13-D2:  The SEFD is 500 to many thousands of Jy.  Something truly 
wrong here.  In addition, the spectra in C1 and C2 are filled with 
'spikes', (like RFI), but not seen on other antennas. 
    ea19-C2:  This one has the 13 MHz 'digital ripple'.
    ea23-A1:  Same as above.
    ea25-A2/C2 and B2/D2:  the SEFD values are 500 to 1000 Jy, with 
highly irregular variation with frequency. 

    Otherwise, the AC products look very good!