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: http://www.naic.edu/~phil/calsbn/sbn.html
Дата изменения: Wed Aug 20 22:36:01 2014
Дата индексирования: Sun Apr 10 02:17:17 2016
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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:
- xxjul14:polB amp (in the dewar) sband hi, was replaced by a
new chalmers amp.This is polA on the outside.
- 01aug13: first stage of amps (both pols) burned up..
- had an sband experiment. ao19 was installed. may receivers
taken down. When trying to bypass the shutters for the missing
receivers, they reversed open and closed. So the tx
transmitted with the shutters open.
- polA in the dewar was replaced with the spare sbn chalmers
amps
- polB in the dewar was replaced one of the sbh amps
- The cables from amp to dewar output are swapped...so
- polAAmp (sbn spare) is polB outside
- polBAmp (sbhi amp) is polA outside.
- 13jan13: updated pointing offsets (after focus move).
- 26nov12: sbn moved up 1.2 inches along focus. (date may have
been 28)
- 20nov12:
cal values fir new sbn receiver installed
- 09nov12: circulator postamp chassis was reversed.
- 28oct12: new sbn receiver installed. sbTx horn also replaced.
- 15mar06: sbn
cal
values remeasured at 2380 and 2280. Installed 10apr06,
backdated to 14oct03.
- 14oct03 turstile stubs switched. Also reversed rf cables
so polA is still polA downstairs. This is to put the "better"
amplifier for the OC echo for the radar experiments.
Calibration
measurements:
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
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.
- Fig 1 shows the az,za distribution for the data. The fit uses
a linear fit out to a za of 14 degrees. Above 14 degrees it
includes a za^2 and za^3 term. It also has 1az, 2az, and 3az
sin, cos terms.
- Fig 2 top plots the gain data and the fit to za. The fit
equation is plotted with the sigma for the fit (in K/Jy). T
- Fig 2 bottom plots the fit residuals (data-fit) vs za.
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:
- shutter closed
- upstairs transfer switch crossed
- 260 IF used
- detect the 100 Mhz band with a 20 usecond time constant.
Do this separately for polA and polB.
- Sample the data at 10 usecs.
The plots show
the pol B ripple (.ps). (.pdf)
- Top figure. This is total power versus time for polA (black)
and polB (red). The polarization's are referred to the dewar
(not the downstairs signal since the xfer switch was in). The
data was smoothed to 10 milliseconds. You can see the jumps in
polB. It is not a sine wave. The signal stays low for .55
seconds and then jumps up (about 2% Tsys) for .28 seconds. The
entire duration is .83 seconds or 1.2 hz.
- Bottom Figure: The 48 seconds of 10 usecond
sampled data was transformed and then the magnitude taken. There
are a set of spikes spaced at .6 hz (with a few harmonics
missing).
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
home_~phil