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History:

• 23mar17: Tsys PolB jumps by 10K (more info)
  
• 13jan13: updated pointing offsets.
  
• 29sep08: installed new cal values. backdated to 18aug05.
  
• 10oct04: installed new cal values. backdated to 15aug04.
• 10sep04: new gain curve installed and back dated to be valid from 15may04.
• 14may04: cal diodes replaced.
• 14may04:  horn moved down in focus direction to put it in focus.
• 29apr04: horn moved x,y direction after feed survey (focus motion not yet done).
• 1999-14may2004  The measured system temperature drifted from 1999 thru 14may2004. This was caused by the cal diodes drifting. On 14may04 the diodes were replaced and the measured system temperature stabilized.

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Calibration measurements: (top)

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Miscellaneous (top)

170817:Tsys polB > Tsys polA, SEFDB/SEFDB (top)

    The Tsys for sbw polB has been higher than Tsys PolA since 23mar17

plot of sbw tsysA,B difference 01jan17 thru 17aug17 (.ps) (.pdf)

• top: tsys (hcorcal) . black polA, red polB
• bottom: TsysA - tsysB
• Looking at the daily tsys output,
  
• 12mar->19mar No tsys measurements (hf heating campaign)
• 20mar17 : tsys, receiver is warm
• 22mar17:  tsys polA 36K, polB47K, but some cal configurations giving unrealistic values (tsys 16k)
• 23mar17:  tsys PolA36k, polB 50K .. all cal configs stabl
•  I looked in the electronics receiver/instrumentation log page to see why the receiver was warmed up,  but the last entry entry in the log was oct 2016  :)...

    To see if the problem was the cal, or a real problem with the system temperature, i looked at the calibration runs for sbw during 2017. Unfortunately, calibration runs were only done in june and july  of 2017

• i  usually check the dewar temperatures of a receiver  before scheduling a calibration run
• The dewar temp for sbw has been 999 for the entire year. Turns out this was a problem with the temperature diode, and not a problem with the receiver....

The gain and Tsys both use the cal value to convert to Kelvins. For the SEFD (Tsys/Gain) the cal dependence cancels out.

• It the cal was a problem, Both Tsys and the gain for polB would be high, but the SEFD for polB  was be the same as polA

The plots show Tsys,gain, and sefd for the jun,july, sbw calibration runs (.ps) (.pdf)

• Page 1: tsys and gain
• top frame: Tsys vs Za.
• + is polA, * is polB
• The colors are different frequencies: 2212:black,2380:red,2690:green, 2850:blue
• TsysA looks higher than tsysB
• 2nd Frame: TsysB/TsysA vs za
• The colors are different frequencies
• the purple line is a ratio of 1.
• Tsys Polb is 20 to 40% higher than polA
• The daily system temperature plots are taken at 2725MHz. So the green + are the closest set.
• 3rd frame: Gain vs Za.
• + is polA, * is polB.
• The different colors are the different frequencies.
• bottom frame: GainB/GainA vs za
• the ratio looks to be greater than 1.
• The median values for the ratios:
• 2212: 1.02
• 2380: 1.09
• 2690: 1.04
• 2850: 1.08
• So the ratios are not close to the Tsys change (25%).
• Page 2: SEFD
• Top frame: SEFD polA,B
• + is polA, * is polB
• The colors are the different frequencies.
• Bottom frame: Ratio SEFD_B/SEFD_A vs za
• The median ratios are:
• 2212:  1.22
• 2380:  1.12
• 2690:  1.24
• 2850:  1.33

SUMMARY:

• Tsys polB for sbw increased from 40 to 50 K on 23mar17.
• This was after a receiver warm up, cool down.
• looking at the SEFDs:
• The ratio of the SEFD_B/SEFD_A is 1.24. This matches the 25% increase in Tsys.
• So the problem is an increase in Tsys (not a problem with the cals).

processing: x101/170817/sbw.pro

30may17 testing the correlated cal on sbw (top)

    Joanna rankin reported trouble with the low correlated cal  on sbw. Her data set was:

• sbw high band
• low correlated cal, 25 hz winking cal
• puppi
• 21apr14  (56768) and 04may14 (56781)

    The data showed the winking cal was present, but there was no correlation between polA and polB (as if the  2 diode cal was used).

    I checked the cima log files, and the low correlated cal was requested...

On 30may17 i took some data using the mock spectrometer:

• sbw with high band filter installed
• rf centered at 2800 Mhz
• hcorcal with hardware winking cal selected.
  
• mock spectrometer:
• full stokes, 1024 channels, 1ms dumps,172 Mhz bw.
  
• A standard on was done with hardware winking cal, followed by a cal on, off (not winking)

Processing the data:

• masgethwcal()  was used to read the winking cal data.
  
• the cal on,offs were split into separate arrays (bwon,bwoff)
• the calon, caloff (10sec) files were input and the two recs were stored in bcal[2]
• the winking cal data (1ms resolution) was stored in bdat=[bwon,bwoff]
• masstokes() was used to use the calon,off to intensity and phase calibrate the data.
• the cal values are used to intensity calibrate the data
• the polA,B phase differences from the system were fit and removed using the atan of stokesU,stokesV ratio
  

The plots show the results of the test (.ps) (.pdf):

• page 1. calon - calOff
• black is stokes I
• green is stokes Q
• red is stokes U
• blue is stokes V
  
• top: cal diff from the 10sec calon, caloff
• bottom: cal diff from the average of the 25hz winking cal data (sampled at 1ms).
• Since the cal diode has the same path to polA and polB (through couplers) it is the same as injecting the cal at an angle of 45 degrees from the polA,polb pickups. So all of the cal power should show up in stokes U...It does,..
• page 2:
• frequency average the calibrated 1ms sampled spectra.. giving total power time series.
• Top: stokes I
• Bottom: Stokes Q (green), stokes (U) red, stokes(V) blue
• You can see the 18K winking cal (9K  polA,9KpolB).
• the green stokes q should be at zero, not  -13K. This is probably a result of bad cal values.
• the current cal values are from 2005. We remeasured sbw back in 2016, but i never finished reducing the cal data (too much rfi..)

Summary:

• The correlated cals are working on the  sbw receiver
• the constant , and the winking cal were both tested.
• I need to update the cal values for sbw.

processing: x101/170530/sbwcal_mock.pro

22sep15: final notched filter for aws rfi (top)

• Top frame: S21, S11 measurements of the two filters
• s21 (filter transmission):black  filter a, red  filter B
• they are down 60db by 2110
• at 2155 they are still down by 55 db
• S11 (filter reflection). Black is filterA, red is filterB

11may15: notched filter for aws rfi (top)

    We received the notched filter to remove the AWS rfi around 2130 (more info on the rfi)
The plots show the results of  Dana's 2 port measurement using the agilent network analyzer (.ps) (.pdf)

• S21 is the loss passsing through the filter
• S11  is the reflected power.
• S22, and S12 were similar
• I also plotted the phase (in deg) for S21

May04 to Sep04  fit GAIN CURVES to calib data.  (top...)

    Gain curves were fit to the sband wide  calibration gain data using  15may04 through 01sep04.  The start of this epoch was after the cals were replaced and the horn had been lowered put it in focus.  The plots show the gain data (black) and the fits (red) for 2212, 2380, 2690, and 2850 Mhz. These gain equations were installed on 10sep04 and back data to be valid starting on 15may04.

• Fig 1 shows the az,za distribution for the data. The fit used a linear fit in za up to za=14. Above 14 degrees terms in (za-14)^2 and (za-14)^3  were included. The fit also included  1az, 2az, and 3az sin, cos terms.
• Fig 2 plots the gain data and the fit to za.  The fit equation is printed with the sigma for the fit (in K/Jy).
• Fig  3 plots the fit residuals (data-fit) vs za.

    The routine gainget() or corhgainget() will now return the sbw gain for data after 15may04 from these
equations. The coefficients can be found in the ascii file  data/gain.datR7 (this is provided in the AO idl
distribution for correlator routines). You can also find a copy of it at AO in /pkg/rsi/local/libao/phil/data/gain.datR7.
Be careful using these routines for data before 15may04. There is not gain curve and the routine should return and
status reflecting that...

may04 to sep04 : System performance of data used to compute gain curves.  (top...)

     Heiles calibration scans done from 15may04 (new cals, horn lowered) thru 01sep04 were used to measure the
system performance. This data was then used to compute the gain curves for use on data taken after 15may04.

    The first set of plots show the system performance with all frequencies overplotted. The sources are identified
by symbol and the frequencies 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. The  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 4 has the pointing errors in az,za.

• Fig 1 2212Mhz Gain,Tsys . 260 points
• Fig 2 2212 Mhz sidelobes,beam efficiencies
• Fig 3 2380 Mhz Gain,Tsys 260 points.
• Fig 4 2380 Mhz sidelobes,beam efficiencies.
• Fig 5 2690 Mhz Gain,Tsys 151 points.
• Fig 6 2690 Mhz sidelobes,beam efficiencies
• Fig 7 2850 Mhz Gain,Tsys 259 points.
• Fig 8 2850 Mhz sidelobes,beam efficiencies

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