LBN SEFD across the reciever band


     The source B0831+17 was tracked rise to set with the lbn system doing 1 minute on off position switching. The receiver is circularly polarized but rapidly moves to linear polarization over a 100 Mhz. The source is < .6% polarized (from the nvss data). The frequency bands used were:
band frequencies
#1 1150,1200,1290,1415
#2 1340,1415,1500,1560
    Frequency band 1 was used rise to 14 degrees za and then the program began alternating between band 1 and band 2. The SEFD was computed for each measurment using chris salters fit to the source flux. A 6.25 Mhz bandwidth was recorded. The radar blanker was not used (so the point at 1340 Mhz may have been affected). The plots shows the SEFD vs frequency and zenith angle.  The figures are: Conclusions:
  1. The SEFD for lbn stays below 4 at low za for 1260 to 1530 Mhz.
  2. Polarization A SEFD is 10 to 20% worse than pol B. The daily system temperatures measured using the cals at 1415 Mhz give TsysA=30 and TsysB=26. The difference 4./26 is 15% and agrees with the SEFD ratio at 1415 Mhz. So the discrepancy is being caused by the difference in Tsys and not the gain (it also means that the calratio at 1415 is probably correct).
processing: x101/020514/