01jul21 monitoring xb spectra for 16 hrs



   The  polB 20db xband hub amplifier had a problem with the power connection. Both of the 20db xband hub amplifiers were replaced on
29jun21 with 2 11.5 db amplifiers. The short rf cables were added to the input so the input cables were no longer stretched.
    On 01jul21 the xband receiver was monitored for 17hours. The setup was:

This page looks at the spectral density function for the 16 hours. The monitoring of the total power can be found
The original intent was to look at rfi for the 16 hours. The ripples in the band pass made it hard to be very sensitive. Instead, we looked at the standing wave.

Processing the data

Plotting the spectra.

    The  first plots show the average spectra  (.ps) (.pdf) :

Plotting the rms/mean by frequency channel

    For each hour of data (3600 seconds), the rms/mean by freq channel was computed for each 172 MHz band.
The 7 bands were then interpolated to a single rms/mean by channel covering 975 MHz.

The plots show the rms/mean by channel  for the 16 1 hour data sets.

rms/mean by channel for polA (.ps) (.pdf)

rms/mean by channel for polB (.ps) (.pdf)

Tracking the location of the ripple with the acf

     A sine wave in the spectra is a spike in the acf (autocorrelation function). To track the location of the peak in the acf:

The plots show the results of the gauss fit to the acf vs hour of day (.ps) (.pdf)


processing: x101/210701/xbspcrfi.pro

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