Sband signal with pads installed



    On 12apr21 we found that the sband signal rfi was so strong that it was causing glitches in the xband signal. The 12meter multiplexes the sband and xband rf signals onto the fiber optics and sends them down to the rcvr room. The udc (up down converter) then selects either the sband or xband signal to convert to 1-2 GHz. The measured power levels showed that the fiber optics was not saturating (fiber output was about -30 dbm, with about 24db loss in fiber the input was less than -5 dbm.. The 1db compression for the fiber is 10dbm.). Later measurements showed that the udc's 1db compression was -35dbm.. So the compression we were seeing in apr21 with the sband signal was probably in the  udc .

    On 7dec21 we placed pads in front of the sband inputs to the rf box in the 12meter pedestal. We tried 10db and then 15 db pads. The current 12meter config also has [15,20] db pads (polA,polB) before the UDC inputs.

Data taking setups used:

    The 12meter tracked blank sky while the data was taken.



Looking at the data:

    The first plots shows the sband spectra (.ps) (.pdf)

    The second plots show 300 second of xband total pwr while sband connected (.ps) (.pdf)


processing: x101/211207/,

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