[evlatests] ea28 reflection

[Rick Perley]

     A short test was run yesterday, to check the status of the strong 
reflection on ea28, on the RCP side.  The reflection is there, although 
perhaps not as bad as during some of my recent observations.

     Attached are three .eps bandpass plots, showing the severity of the 
problem.  The spectral resolution is 500 kHz.  Ringing, with a period of 
10 ch = 5 MHz, is seen in all spectral windows, although the effect is 
much reduced in the highest frequencies. this frequency corresponds to a 
(free-space) distance between reflection points of 30 meters.

     Plot 1 shows the lower eight spectral windows, plot 2 the upper 
eight, and plot 3 is spw11 alone (this is the SPW with the strongest 
effect).

     No other antenna shows anything close to this.  For those 
interested, I can provide plots for any, or all, other antenna.

     Because this high frequency ringing is highly time variable, these 
oscillations cannot be easily calibrated out (likely, not at all).  My 
opinion is that this problem needs to be adequately addressed, or the 
monitor should be disconnected.

     Rick

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