Monitoring the system temperature of the various receivers

april,2002

The plots:
    Tsys polA, polB
    Tsys PolA - TsysPolB
    The system temperature of each receiver is measured each day by the operators using the correlator. The telescope is normally sitting at 10 deg za and an azimuth of 270 (although it occasionally may be at a different az,za). The cal is flipped on/off once a second  3 times. The total power is used to compute the cal deflection and then Tsys. There are up to 8 different kinds of cals using 2 diodes on each receiver. The high cals are:
  • high uncorrelated cal with 2 diodes (diode1->polA,diode2->polB)
  • high correlated cal with 1 diode (diode1->polA,diode1->polB)
  • high uncorrelated cal with crossover (diode2->polA,diode1->polB)
  • high correlated cal with 90 deg phase shift (diode2->polA,diode2_90degphase shift->polB)
  •     There is a similar set of low cals (that go through a 10 db coupler). The table below shows the receiver name, frequency range of the receiver, frequency where the system temperature is measured, and the cals that are available.

        For alfa a slightly different method is used:
     

    receiver cals and frequency of measurement
    receiver freq. range 
    Mhz
    cals freq. (Mhz) of 
    measurement
    327 312-347 1 correlated cal 327
    430 425-435 all 8 cals 431
    800
    700-800
    1 correlated cal 740
    lbw 1120-1730 all  8 cals 1400
    alfa
    1220-1520
    1 correlated
    1375-1520
    sbw 1800-3100 all 8 cals 2290
    sbn 2330-2430 1 correlated cal 2380
    sbh 3000-4000 all 8 cals 3500
    cband 3850-6000 all 8 cals 5000
    xband 8000-10000 all 8 cals 8800

    There is a daily ascii output that is stored in the control room. An sample ouput looks like:

    line0: Thu Jan  1 16:19:47 2004 az/za lst: 270.0004 10.0000 22:36:05
    line1: rcv  5 1400.0 6  3 0 if1 -40.78 -40.17  if2 -54.59 -54.28  cor  0.91  0.94 11 11
    line2: 5     hcal  9.550  9.810   27.8   27.2
     
    col descriptions
    line 0 columns line 0 col descriptions
    Thu Jan  1 16:19:47 2004 date 
    270.0004 10.0000 22:36:05 azimuth, zenith angle, lst when data was taken.
    line 1 columns line 1 col descriptions
    rcv 5 receiver numbers: 
    1-327,2-430,3=610,5-lbw,6-lbn,7-lbw,9-cband,11-xband,12-sbn
    1400.0 frequency in Mhz where the data was taken
    6 bandwidth number: 2-25,3-12.5,4-6.25,5-3.125,6-1.5...
    3 integration time in seconds for cal
    0 lbw hybrid. 0 out, 1 in
    if1 -40.78 -40.17 

     

    pwr dbm measured with upstairs power meter.
    -40 is optimal for lbw,lbn,sbn 
    -32 is optimal for cband,sbw,xband, 
    430,327 can have less (say -48) since they are narrower bands.
     if2 -54.59 -54.28 power in dbm from the downstairs power meter.
    cor  0.91 0.94 correlator 0 lag pola,polB. This is the ratio of measured to optimum power. 
    If the value is far from 1 then the power levels were wrong (say 20%)
    11 11 The attenuator values used at the correlator (polA,polB) 
    The attenutaors go 0 to 15 db
    line 2 columns line 2 col descriptions
    5 receiver number
    hcal 
     

     

    H is high cal, L is lowCal, D1 is diode 1,D2 is diode2 
    H/Lcal: uncorrelated cal (two diodes) D1->pola,D2->polB 
    L/Lxcal: uncorrelated cross over (two diodes)  D1->polB,D2->polB 
    H/Lcorcal: correlated cal (one diode). D1->polA,D1->polB 
    H/L90cal: correlate 90deg phaseshift cal. D2->polA,D2+90deg->polB
    9.550  9.810 Calvalue in kelvins used (polA,polB)
    27.8   27.2 Tsys computed in kelvins (polA,polB


    The plots:

        There are now 2 sets of tsys plots. The first set shows Tsys versus date . The second set shows the difference TsysPolA - TsyspolB.

    Tsys Vs date:

        These plots are updated at 3 am each morning. There is a set  for the last 30 days, the year to date, and for previous years. For those receivers with multiple cals, only the high cals are plotted. Pol A is the solid line while pol B is the dashed line. The tsys from each cal type is plotted in a different color.
     


    Tsys for the various receivers by year

    327,800
    gr430,ch430
    lbw
    alfa
    sbn,sbw
    sbh,cband
    cbh,xband
    YearToDate
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    2016
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    2015
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    2014
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    2013
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    2012
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    2011
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    2010
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    2009
    327,800
    gr430,ch430
    lbw
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    sbn,sbw
    sbh,cband
    cbh,xband
    2008
    327,610
    gr430,ch430
    lbw

    sbn,sbw
    sbh,cband
    cbh,xband
    2007
    327,610
    gr430,ch430
    lbw

    sbn,sbw
    sbh,cband
    cbh,xband
    2006
    327,610
    gr430,ch430
    lbw

    sbn,sbw
    sbh,cband
    cbh,xband
    2005
    327,610
    gr430,ch430
    lbw

    sbn,sbw
    sbh,cband
    cbh,xband
    2004
    327,430,610
     
    lbw,lbn

    sbn,sbw
    sbh,cband
    cbh,xband
    2003
    327,430,610
     
    lbw,lbn

    sbn,sbw
    sbh,cband
    xband
    2002
    327,430,610
     
    lbw,lbn

    sbn,sbw
    sbh,cband
    xband
    2001
     327,430,610
     
    lbw,lbn

    sbn,sbw
    cband
    xband
    2000
    327,430,610
     
    lbw,lbn

    sbn,sbw
    cband
     
    1999
    430,610
     
    lbw,lbn

    sbn,sbw
    cband
     

    TsysPolA - TsysPolB:

        Each plot has:     The difference plots show receiver variation more clearly than the Tsys plots.  Some of these differences could be attributed to polarized power from the sky  for the linearly polarized feeds.  The circularly polarized feeds (430, sbn, xb) should not be affected by linearly polarized power.  The plots are made by year. For the current year they are updated at 3am daily. For each pol, Tsys is the median of all non-zero cal measurements (hcal,hcorcal,hxcal, etc..).

        The system temperature is taken daily and then recorded. If the cals are changed, then it may take awhile for the new cal values to be measured. So there may be periods of time when old cal values are being used on new cal diodes. When the new cal values are installed , you could see a jump in the system temperature. You should be able to identify these jumps by going to the cal values page and looking to see when the new cal values were installed. Gradual drifts in TsysA-TsysB are probably problems with the cal diodes drifting.
     
    TsysPolA -TsysPolB by Rcvr and Year
    year
    327
    430gr
    430ch
    800
    lbw
    alfa
    sbn
    sbw
    sbh
    cb
     cbh
    xb
    2017
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    2016
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    2015
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    2014
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    2013
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    2012
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    2011
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    2010
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    2009
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    2008
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    2007
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    2006
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    2005
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    2004
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    2003
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    2002
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    notes:

    2010:


    2006

    2005

    2004


    2003


    2002

  • 04apr02 sbw -updated hcorcal to be measured value from absorber cal measurement sep01. other cal values unchanged
  • 06apr02 lbw - left vacumn pump running on lbw dewar. 70K temp went 120=>80K Tsys dropped by a view degrees . must be  a leak in the dewar.
  • 11jul02 - lbn cals values changed. Tsys jumped.
  • processing: x101/tsys/monitor/tsysmondaily.pro,  tsysmonyears.pro
     home_~phil