Intro
The 12meter xband signal was sampled at 10Hz on
26apr21 around 13:45 for 48 minutes. The setup was:
- telescope tracking blank sky:
- :ra:05:18:00, dec:-08:46:37
- start az el: 120,42
- (the sun had already transited.)
- The sband signal was terminated with 50 ohms
at the input to the postamp chassis.
- 7 x 172 MHz bands covering xband were taken with the mock
spectrometer
- 8192 channels/band, 2 pols .1 second sampling of
spectra.
- data was taken for 2984 seconds (48 minutes).
Plotting the data.
total
power vs time for the 48 minutes (.ps)
(.pdf)
- Black is polA, red is polB
- Each frame is a 172MHz band
- The data has been normalized to the mean value (tsys)
- Most of the variation is happening in all the bands
simultaneously.
- Page 1 bottom:burst from 900 to 1200 seconds is rfi
(8318 to 8346 MHz)
- There seems to be more variation in the total power
than you would expect
Spectra
of the total power time series (.ps) (.pdf)
- The 29840 .1 sec total power samples were
transformed for each freq band
- spc=abs(fft(tptimeseries -meanTp))
- 5 Hz bandwidth, .0003 Hz freq resolution
- The plots were smoothed/decimated by 10 (to .003 Hz
resolution)
- top : polA
- bottom:Polb
- The first and last bands seem to have some artifacts. But
these bands are only half filed with power (from the filter
cutoff).
Summary
- The dropouts seen back on 12apr21 were not present after
terminating the sband input at the postamp chassis.
- The total power varied by about 1% . It is the same
for all the bands.
- Rfi was seen in 8318 to 8346 MHz for about 5
minutes.
processing: x101/210426/xbmontpslow.pro