sband narrow calibration

aug,2002

     The cband  receiver covers 3.95 to 6.05 Ghz. It is a native linear receiver with the option to create circulars using a hybrid in the iflo cabinets.


Sections:

History
Recent system performance measurements
Daily monitoring of Tsys
Dewar temperatures
calibration measurements
Measurements by date
cal values


History:


Calibration measurements:


21apr16: calibration runs after painting shutdown to check pointing, system performance
12mar14: calibration runs made after the m8-4 cable repair
13jan13: calibration results: jun12-dec12. updated pointing offset.
06dec12: compare old,new (out of focus), new (in focus) calibration runs.
23nov12: calibration runs comparing the old and new receiver(out ofocus).
20nov12: cal values fir new sbn receiver  installed
08sep11: sbn,alfa calibration runs after alfa installed.
mar03: sband gain calibration mar03 to feb04. (gain curves.)
mar03: system performance for the data set used to make the gain curve.
sep01: sband gain calibration. (gain curves.)
01aug01: pointing and gain changes from tertiary motor installation.
24may01: pointing and gain on 3C138 (24may01)
jan01: sband gain during and after reflector surface adjusted
aug/sep00: sband narrow calibration(gain curves)


Measurement by date


08may17: sband shutter not opening correctly.
21apr16: calibration runs after painting shutdown to check pointing, system performance
19aug14: reinstalling  the chalmers amplifiers.
12mar14: calibration runs made after the m8-4 cable repair
13jan13: calibration results: jun12-dec12. updated pointing offset.
06dec12: compare old,new (out of focus), new (in focus) calibration runs.
23nov12: calibration runs comparing the old and new receiver.
20nov12: cal values fir new sbn receiver  installed
14feb12: tsys contributions for various receiver configurations.
10aug12: new sbandnarrow polarizer plots (septumS22.jpg) (septumS21.jpg)
08sep11: sbn,alfa calibration runs after alfa installed.
20jan11: rfi appears at 2380 Mhz.
05may06: The performance of the new sband Tx horn.
10apr06: sbn cal values remeasured.
01jul05: sbn warmup during sband radar run.
13oct04 1.2 hz total power ripple.
mar03: sband gain calibration mar03 to feb04. (gain curves.)
mar03: system performance for the data set used to make the gain curve.
dec02: SEFD polarization ratio shows that TsysA,B difference is real. (dec02)
sep01: sband gain calibration. (gain curves.)
01aug01: pointing and gain changes from tertiary motor installation.
24may01: pointing and gain on 3C138 (24may01)
jan01: sband gain during and after reflector surface adjusted
aug/sep00: sband narrow calibration(gain curves)


May03 to Feb04  fit GAIN CURVES to calib data.  (top)

link to gain curve plot

    A gain curve was fit to the sbn gain data  taken between 01mar03 and 29feb04.This data is described below.The plots show the gain data (black) and the fits (red) for 2380 Mhz.This gain equation was installed on 09mar04.


    The routine gainget() or corhgainget() will now return the sbn gain for data taken after 01mar03 using this equation. The coefficients can be found in the ascii file  data/gain.datR12 (this is provided in the AO idl distribution for correlator routines). You can also find a copy of it at AO in /home/phil/idl/data/gain.datR12.

processing: x101/cb/may03/dogainfit.pro


mar03 thru feb04 : System performance of data used to compute gain curves.  (top)

     Heiles calibration scans done from 01mar03 (after shimming) thru 29feb04 were used to measure the  system performance. This data was then used to compute the gain curves used after 01mar03.
    The plot shows the system performance for this dataset.The sources are identified by color.
  • Fig 1 shows the distributions on the dish of the measurements.
  • Fig 2 has the Gain in Kelvins/Jansky. This relies on the cals and the source flux. Ths  next plot is Tsys vs za in Kelvins followed by the SEFD  (System Equivalent Flux density) in Janskies / Tsys. At the bottom is the average beam width in arc seconds.
  • Fig 3 plots the coma parameter, first sidelobe height below the peak, the main beam efficiency, followed by the main beam + 1st sidelobe beam efficiency.
  • Fig 3 has the pointing errors in az,za, and total (added in quadrature) for the data.
  • processing: x101/sbn/mar03/doit.pro


    Miscellaneous section.

    01jul05 dewar warms up during radar run

        On 01jul05 the sbn dewar warmed up during an sband radar run. The plot shows when the warmup occurred (.ps) (.pdf).

    13oct04 1.2 hz total power ripple.

        A  ripple in time was seen in polB  of the sbn receiver. The ripple was there with the horn shutter open or closed so it was not coming from an out of band signal. It was seen in polB only. When the upstairs transfer switch was crossed, then the ripple moved to polA. This shows that it is before the transfer switch. Data was taken on 13oct04  using the radar interface (ri). The setup was: The plots show the pol B ripple (.ps).  (.pdf)     This ripple  looks like it is tied to the 1.2 hz cycle of the dewar refrigerator. The transition from low to high is sharp. In the smoothed data it is taking less than 10 millseconds. This will increase the number of harmonics of the fundamental.
    processing: x101/041013/dori.pro


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