PolA ripple 2011-2012

Mar 2012-Dec12



    The 430 dome receiver has had trouble with polA during 2011 and 2012. There have been:


History and Measurements in reverse order: (top)

19nov12: take data while switching radio -> radar mode switch

    On 19nov12 spectra were taken while the radar, radioastronomy switched was moved from radio astronomy -> radar mode -> radio astronomy.

The plots show the spectra while the switch was moved (.ps) (.pdf):


processing: x101/121119/430ripple.pro

nov12-dec12:A2704 430 continuum mapping. polA ripples.

    Project a2704 is doing continuum mapping at 430 Mhz using the dome receiver. Their setup is:

Images showing spectral averages for each strip
To get an idea of the amplitude of the ripples, the spectra for each day were averaged and then over plotted (.ps) (.pdf):


processing: x101/121116/a2704_430ripples.pro

430 x111 data from oct,nov 12  (top)

    x111 rfi monitoring data from  oct,nov12 was examined to see when the 430 polA ripple was present.

Data processing:
 The plots show the the average spectra for each 60 sec scan (.ps) (.pdf):


processing: x101/121119/gr430ripple_x111.pro

30mar12 - terminate input to dewar at various spots. (top)

    On 30mar12 we terminated the input to the dewar at various locations and then took measurements looking for ripple.
The measurements consisited of:

The sections before the dewar are:

The sequence of terminations was:
The plots show the on/off-1 for various termination locations (.ps) (.pdf):
Dynamic spectra were made for the 530 seconds of scan 73 (.gif):


processing: x101/120330/chk430ripple.pro

26mar12- PolA ripple with 430 on load.  (top)

    On 26mar12 data was taken with the Gregorian dome on load to check out the polA ripple. It had been noticed previously that the Jennings relay for polA (that switches between load and sky) gave non-repeatable results when switched from load to antenna and then back to load.
 The setup was:

The first set of plots shows the total power stability vs time (.ps) (.pdf):
The 2nd set of plots shows the frequency baseline stability (.ps) (.pdf):


processing x101/120326/chk430.pro.

processing x101/120326/chk430.pro.

17mar12 - a2599 has bad ripple in polA  (top)

    a2599 reported bad  ripple in polA.
The plots show a 300 second average spectra using the wapps (.ps) (.pdf)

processing: x101/120317/chk430.pro

x111 data showing polA ripple mar11 to jun11 (top)

   The 430 dome polA bandpass has shown variations in its bandpass. They  first appeared on 30mar11. The x111 rfi monitoring data was used to check when it occurred. The x111 data processing was:
The plots show the 430 dome x111 rfi monitoring data for mar thru 22jun 2011 (.ps) (.pdf):
processing: x101/110428/430polAripple.pro