Taking the data: (top)

    rfi monitoring data (project x111) is taken whenever there is any unused telescope time. The setup is:

• Use interim correlator to take the data
• 9 level sampling,1 second dumps, 60 seconds of data followed by calon,caloff
• use 4*25 MHz bands at each integration
• Offset the 4 bands in freq by 23 MHz (so there is some overlap).
• The telescope is stationary when the data is taken (so the sky drifts through the beam).
  
• For each receiver start at the lowest frequency and move in  23*4 MHz steps every 65 seconds until the entire band is covered.
• When a band is complete, move to the next receiver.
• continue cycling till the operator aborts the program.
• The information to control the program is in files:/share/obs4/usr/x111
• x111auto.corsu  .. interim correlator setup
• x111auto.proc (in /home/online/Tcl/Proc/astro/cor)  tcl command to run at the vw% prompt in vxWorks to run the program.
  
• x111auto.dat
• file containing all of the receivers and bands to observe.
• The program x111auto just steps through this file.
• x111auto.exc - list of receivers to ignore. Any receiver names in this file will be skipped when they are read in x111auto.dat
• Use this file to temporarily skip over receivers that are out of service.
• x111auto.last
• file containing last line in x111auto.dat that was processed.
  
• x111auto.proc uses this to decide where to start each run.
• x111auto.log
• x111auto.proc writes each scan as it is performed to this file.

Making the images: (top)

    Images of the x111data are made every so often. The images consist of:

• Dynamic spectra (spectral density vs freq and time) are made doing:
• data it taken in 60 second blocks (1 sec recs). There is then a delay before the program cycles around to the next time this freq block is measured.
  
• 4*25 MHz records are input for a specified data range (this may be one or 2 months).
• For each 60 second block of data
• the median spectrum is computed
• a robust harmonic fit is made (1st order linear, 20th order harmonic) and then used to flatten the 60 seconds of data.
• A fit rather than a median is used so we don't get rid of constant tones.
  
• After flattening all of the data, the 4x25 MHz data is interpolated to a constant frequency spacing (getting rid of the freq overlap)
• The image has 1 subtracted and then clipped to +/- .1 Tsys and plotted
•  Some issues with the images:
• horizontal bright lines may be continuum sources drifting through the beam.
• For some receivers is didn't start on a block of 4x25 (because the first few bands may have been cut off by the filters.
• In this case, the 4 bands on one row may have not been taken all at the same time.

x111 dynamic spectra  images: (top)

lband:

• (*0) the bandpass starts to cut off the signal around 1120 and 1745 MHz
  
• (1) the rightmost band 1745-1767 is on the edge of the bandpass filter.
  
• 1175 gps L5
• 1228: gps L2
• 1232,1247,142,1257 : punta salinas radar in modeA
• 1245 - glonass L2
• 1268 - Chinese compass gns
  
• 1270 - remy radar
• 1330,1350 FAA airport radar
• 1381.05 gps L3
• 1530-1550 inmarsat
  
• 1575 gps L1
• 1600 - glonass L1
• 1620 - iridium