• apr11 - jul11
• oct11 - dec11
• may12-
  

• 01jul11: beam2a has 4% jumps 28,29jun11
  
• 23may11: Adjusting beam1 bias voltages fixes  jumps in beam1b cal deflection
• 20may11: beam1b jump happens at the same time as the 20K stage temp diode jumps.

Intro:

• Setup:
• Dome moves 2 to 20 degrees then back down. Az is at the meridian.
  
• mock spectrometer  setup:
  
• two 172 MHz bandwidths centered at 1300 and 1450. the plots below use the 1450 MHz band.
• sample spectra at 1 millisecond integrations.
• winking cal  with 20 milliseconds on and then 20 milliseconds off
• Processing:
• Average calOn, calOff spectra to .1 second each (throwing out the 1 millisecond for each cal transition).
  
• Compute total power for each .1 second calOn, calOff spectra.
  
• compute calDeflctionTp= CalOnTp - calOffTp giving .2 second resolution.
  
• Fit a linear  ramp to calDeflectionTp for the entire nights data. Use this to convert from spectrometer counts to calDeflection units.
• Plotting:
• Page 1: calOn,caloff buffers and calDeflection using spectrometer counts:
• The data for the plots has been median filtered to 1 second.
  
• 1st : PolA calOnTotal power (black) calOffTotal power (red).
  
• 2nd: PolB calOnTotal power (black) calOffTotal power (red).
• 3rd: PolA  calOnTp - calOffTp. the green line is a linear fit to the cal Deflection
  
• 4th : PolB calOnTp - calOffTp
  
• Page 2: CalDeflection/LinearfitToCal.
• Dividing by the linear fit to the cal changes the units from spectrometer counts to cal units.
  
• 1st: polA, 2nd polB
• the black trace has been median filtered to 1 second, the red trace has been median filtered to 12.2 seconds.
• Outliers (< .6cal, > 2.0 cal) were not included in the filtering.
  
• Each title contains the rms of the cal deflection for the entire nite (before any filtering).
  
• CalOn-calOff in spectrometer units
• 3rd polA
• 4th polB
• A linear fit (green line) is done for the entire dataset. This is used in plot 2 to normalize to calDeflection.
• Cal deflection vs Za: rightmost column:
• Plot cal deflection vs za for each beam. black is pola, red is polB. The data has beem smoothed to 12.2  seconds with a median filter.
  

• nov11-dec11:
• bm0b:moving +/- 5%15-18nov11
• bm1b:
  
• 15-18nov11 jumps down then backup by 3-5%
  
• 20,23,26 up 5%.
• 28nov11 5% jump start of run
• 01-02dec11:variations to 5%
  
• bm2a:
•  08nov11. jumped up during one of the cals
• 17nov11: drifts down >5% over about 10 minutes then jumps up +6%
• 28nov11: unstable.  up to 4% changes
• 01-02dec11: drifts then jumps.
  
• 01nov11: started cals. One of the cal runs has a caldeflection jump for all beams.
• This was file 00200 which had the winking cal  start one dump late (phase=1 on the a2130 run table).
  
• In this case, the last 2 dumps of each cal on ,off are dropped rather than just the last.
• The shorter integration is recorded in the exposure keyword in the header.
  
• The plots made on this page were not scaling by the exposure (it was assuming all the integrations were the same length).
  
• For the days after 01nov11 i changed the plotting program to scale to the median(exposure) of each day.
  
• 24oct11: stopped and restarted observing. only plotted the first part send attenuators changed in second part.
  
• 20oct11: beam1a switched to use fiber 6b, beam6b using fiber 1a
• After this, beam1a has 2%amplitude variation with za.
  
• 19oct11: beam1a tsys-> 150 after fiber connectors cleaned.
  
• 13apr11: 1b has instabilities. continues till 23may11.
  
• 14apr11: 4b linear decrease caldeflection with za this continues for many days
  
• 20apr11:2b increase caldefl at low za dip around za=5. this continues for many days
  
• 21apr11:4b caldefl increase za > 16. this continues for many days. linear increase with za has stopped
  
• 27apr11: 2b caldefl is starting to flatten out.
• 01may11:2b caldefl dip around 5 deg back. 4b continues increase at high za.
• 20may11:4b  caldefl linear ramp returns.Still have increase at high za.
• 21may11:2b increase at low za back, linear ramp 4b with no extra increase at high za.
• 22may11: 2b increase low za, decreasing ramp with za. 4b is flat today.
• 23may11: 1b problem is fixed. gate voltage returned to pre 16feb11 values.
• 2b continues with increase low za and ramp
• 4b flat
  
• 05jun11:
  
• 2b caldefl: linear ramp increasing caldeflection with za
• also show an increase in za 14-15 degs but only when coming down in za.
• 4b caldefl linear ramp increasing with za.
• 21jun11:
• 2A 1 4% jump about 400 minutes into run.
• 23jun11: bias card for beam 2 replaced.
  
• beam 2a amp1 drain current had large oscillations.
• putting in new card stopped the oscillations.
  
• 28,29jun11
• 2A jumps up 4% for about 40 minutes then back down.
• October run:
• beam 6b bad
• beam4a has higher Tsys.
• Drain current turned down to keep it from oscillating.
• 
  

Cal deflection vs za. (top)

• Each plot holds the data for 1 day , all 6 beams.
  
• Black is polA, red is polB.

• that looks a lot like the za dependence of the telescope gain and Tsys.
• This was first seen on 21apr11.
• The cal value increases by about 3% at 19 deg za.
• This variation is not caused by the gradient in za at high za.
• Suppose calOn comes before cal Off.
• Going up calOff is taken at a larger za so the cal deflection is smaller because of a za Tsys gradient.
• Going down calOff is taken at a smaller za that calOn so the calDeflection would be larger because of a Tsys gradient.
• The plots show that the cal deflection only increases with za. For a za Tsys gradient it should decease and increase because of the change in za direction.

• 30apr11: The ripple was first seen
  
• 23may11: A low za increase in caldeflection was seen
  
• 05jun11: increase around 14-15 deg za seen.
•  The increase was only seen when  going down in za.
  
• 05jun11 started observing with the dome at 360 degs (looking south). The previous dataset was dome looking north.
  
• beam 2b has a ripple around za=5. This started on 20apr11.

• The amount of cal that gets into the receiver increases with za above 15 (but only in polB)
• the bm 4 polB probe is moving with za?
• Some of the cal  signal goes out the horn and then get reflected back. More of this reflection occurs at high za?
  
• The electronic gain increases with za above 15 degrees.
• Some cables are moving with za? but only for beam 4a,2b?
  
• Higher za does have higher Tsys. (but 2b does the opposite at low za sometimes?)
  
• the gain increases as the signal get stronger?
• Somehow the spectrometer is increasing the output gain as the input level increases?
  
• input level too low?
• It is suspicious that the increase in cal deflection has the same functional dependence as the tsys increase (but only for 4a)
  

 Measurements by date

01jul11: Beam 2a caldeflection has 4% jumps.

• The bias card for beam2 was replaced on 23jun11.
• The beam2a amp1 drain current oscillations went away.
• The Tsys did not get any better.
• On  28 and 29 jun11 the caldeflection measured by a2130 jumped by about 4%. The jump lasted for about 40 minutes before returning.
  
• see 28jun11 beam2 (col 4) in the table above.
• The jump was probably not related to the bias card change since the jump started 5 days after the card was changed (data from 24-27 jun11 was ok.. as well as 30jun11).

23may11: Adjusting beam1 bias voltages fixes  jumps in beam1b cal deflection

• 22may11: beam1 cal deflection before bias change
• 23may11: beam1 caldeflction after bias change

• changing the stage 3 drain voltage level to a lower value on 16feb11 caused bm1b output to jump around. The leds are more sensitive to power supply jumps at the lower voltage.
• restoring the drain voltage to the pre 16feb11 values fixed the problem.
• beam 5b has jumps in the cal deflection (up to 2%). This beam also has a lower stage 3 gate voltage. Maybe if should be adjusted upward (as long is it doesn't cause the oscillations coupling in from dead beam 6 to increase).

20may11: beam1b jump happens at the same time as the 20K stage temp diode jumps.

• Beam 1b showed a jump of 10% in the cal deflection about 40 minutes after 20:00 ast 20may11.
  
• the plot shows that the cal deflection jumped when the Dewar diode temps jumped (.ps) (.pdf):
• frames 1,2 show the cal deflection for alfa beam1a and b.
• Frame 3 shows the temperature diodes for the 20 K stage in the alfa dewar for the same time range.
• The cal deflection is not a jump in Tsys since the calOn,calOff difference is taken every 20 milliseconds.
• The negative slope of the cal deflection from 40 minutes -> 100 minutes also corresponds to the temperature diode values decreasing.
• processing: x101/110520/a2130bm1b.pro