TGBT14A_912_79 - Bank to bank variations with noise source

Goals

  • test banks E through H with a new, flat-bandpass, noise source.

Details

  • set up the new noise source, through the attenuator, through an 8-way splitter, to VEGAS Banks E-H
  • Start with VEGAS in mode 4, then switch to mode 1
  • John puts in a 300 MHz, low pass filter
  • Configure bank_gain_mode4_cband_nocal
  • setValues 2**27.5
  • attenuator setting 4dB
  • Scan 1 - 10 secs
  • att setting 5dB
  • Scan 2 - 10 secs
  • form ratio Scan 1 / Scan 2 for all four banks (pol 0). Results look extremely similar from bank to bank
  • remove low pass filter, need to set att to 7 dB to get back to -20dBm
  • filtersnap now around -23dBm - SetValues 2**28
  • Scan 3 - 10 secs
  • set attenuator to 8dB
  • Scan 4 - 10 secs
  • form ratio Scan 3 / Scan 4. Again, results look extremely similar.
  • Connect the noise source to the inputs of the VEGAS IF module. Need to remove amplifier, set attenuator to 20dB
  • SetValues 2**27
  • Scan 5 - 10 secs
  • Set attenuator to 21dB
  • Scan 6 - 10 secs
  • Set attenuator to 25dB
  • Scan 7 - 10 secs
  • set attenuator to 15 dB
  • Scan 8 - 10 secs
  • have to stop at this point

  • reconfigure to normal.
  • Bank H now seems to have too much gain in the Converter Rack! Put the 10dB pad back onto the input to VEGAS

-- RichardPrestage - 2015-03-06
Topic revision: r2 - 2015-03-06, RichardPrestage
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