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610 receiver calibration

Last modified 26aug00


    The 610 receiver was using the same model as the lband narrow receiver (since it was the closest receiver on the rotary floor). I  did a quick check on the pointing and found it to be way off (> 5 arcminutes).  I updated the pointing model and then proceeded to do 5 cross scan pairs to measure the performance (updating the pointing increased the gain by about 5db).The setup was:

  • 611.5 Mhz, 2 Mhz bw (using 30Mhz If butterworth filter) .
  • detected the signal with a 20 millisecond time constant and sampled it at 100 hz . Each polarization was sampled separately
  • A 2 second calOn/off was at the start of the run.
  • 5 sets of total power crosses in az/za on the the source J1347+122 (7.53 Jy at 611.5 ..kuerhl et al) were done. Each strip (az or za) was 30 arcminutes (great circle) and lasted 2 minutes each.
    •     The cal on/off was used to convert a/d counts to kelvins (calvalue:s19.76 ,  15.4 K). Each strip was then fit for a gaussian plus a constant offset. The entire strip was used without editing out any interference. The fives strips were then averaged and the calibration data was computed.
     
     
    SefdA
    SefdB
    TsysA
    TsysB
    GainA
    GainB
    PntErrA
    PntErrB
    beamWdA
    beamWdB
     
    Jy/Tsys
    Jy/Tsys
    K
    K
    K/Jy
    K/Jy
    Asecs
    Asecs
    Asecs
    Asecs
    azSwing
    17.9
    14.2
    143.8
    120.2
    8.1
    8.5
    9.2
    -5.7
    432.7
    419.2
    zaSwing
    17.6
    13.9
    144.0
    119.7
    8.2
    8.6
    -12.8
    -21.4
    476.6
    494.2

    The plot shows The 5 sets overplotted versus pointing error. The solid lines are polB and the dashed lines are polA. The azimuth and zenith angle strips are plotted in different colors (which don't show up to well on the postscript plot!!). The beams widths in azimuth and zenith angle should be different because the beam is ellipitcal (700 za by 776' az). The ratio's for polA are correct while polB are a bit off (probably interference screwing up the fit a little).

    When using this receiver it is important to use a narrow filter because of interference (tv station). The normal output of the system is at 260Mhz. To use the 30Mhz IF filters you need to modify the standard ifsetup to mix down to 30 Mhz (the signals will then come out under the 4 synthesizers in the if/lo rack downstairs).
    ifsetup 610 611.5
    if2 "if2_syndest 1 1 1 1 if2_synfr 290e6 290e6 290e6 290e6"
    The first two outputs will be polA and the 2nd two will be polB (i need to check this since when i did it , polA, and polB were switched). 

    processing: x101/23aug00/gainstrips.pro, datafile: datafile.23aug00.x101.1
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