Intro:

• both mock groups in use (g0 and g1).
• hi res mode to (86, 57 MHz bw) depending on rcvr.
• offset the bands to get rid of Dc spike
• Use new pshift parameter to downshift everyother butterfly stage.
• 1 second dumps
• 240 seconds on and off source and calibrator.
• 165MHz clock freq was used.
  

21apr13: jumps i adjacent bands after processing

    A2765 was doing double position switching on arp220 using 8-9 Ghz of the xband receiver. Both groups of the mock spectrometer were used to cover the 1 Ghz (with 82/8192 or 10Khz resolution). The data was processed with  masdpsp procedure and then plotted.
There were 3 dps patterns taken.

    Chris mentioned that the different bands of given pattern did not have close to the same values.

the plots show the dps results for the 3 patterns (.ps) (.pdf):

• Each frame is a separate dps pattern ( (srcOn-srcOff)/(bpcOn-bpcOff))
• Black is polA, red is polB
• The data has been smoothed by 9 channels
• The green lines are mock group 0, the blue lines are mock group1.
  
• The solid line is the start of a spectra, the dashed line is the end of a spectra.

Summary:

• The first 2 patterns showed a positive slope vs frequency. The 3 pattern did not show this.
• The jumps occurred mainly in the first two patterns.
• PolA and polB had similar jumps and slopes.
  
• The jumps occurred at mixer boundaries, not group boundaries.
• the 2nd if/lo creates 7 separate freq bands.
  
• Each of these bands is then sent to a group 0 and group 1 mock.
• Since the jumps occurred on mixer boundaries, the jumps are not coming from group 0 or group 1 of the mocks.
• The problem is probably not in the mock boxes.
  
• The jumps could come from the mock mixers or the if/lo mixers.
• The dashed blue line shows the end of each mixer band. Reading left to right
• band 1, low, synth 1
  
• band 2, synth 5 , jump from band1)
  
• band 3,synth 2 (no jump from band 2)
• band 4,synth 6, jump from band3
• band 5,synth 3, jump from band 4
• band 6,synth 7, jump from band 5
• band 7,synth 4, small jump from band 6
• The jumps in the 1st two patterns occurred at the same band boundaries.
• Assuming that the freq slope is wrong it could be caused by:
• Something that has a freq dependence that changes over time
• the calibrator was taken before the source.
  
• I wonder if a loose connection has a frequency dependence.
  

04nov12:1 mock with glitches. 1 with ripple in polB for 1 pattern

    04nov12 was the first day. The cband receiver was used. Some problems seen were:

• b1s1g1 polA (grp 1 second box pdev-108) had lots of 1 channel spikes in the spectra.
• These were bits flipping in the fpga.You can tell since the jumps were discrete.
• We've seen this before when hires mode (decimate bw below 172MHz)  was used.
  
• The normal solution to this was to decrease the bandwidth from 172 MHz to around 165 MHz. That would normally stop the jumps
• They were already using165 MHz clock rate so this was not normal
• I ran the diagnostics (rdcomp). b1s1g1 (pdevs-108) failed the diags even at 160MHz.
  
• We replaced this pdev spectrometer and the diags then ran ok.
• Ripple was seen in 1 band of the 1st  dps scan (.ps) (.pdf)
• Page 1: dps spectra for each dps pattern
• The vertical scale is in units of the calibrator.
• Red in polA, green is polB
• The data has been smoothed by 21 channels 10.5 Khz*21=220 Khz resolution.
  
• Each frame overplots the 14 spectra of each dps pattern
• frame 1-3 is dps pattern 1 thru 3
• The red vertical lines around 4200 is the bad mock box (b1s1g1). It was replaced.
• There is lots of rfi 4000-4200 MHz.
• there is a ripple in polB (green) near 4850 MHz of the 1st dps scan. it is not seen in the other dps patterns.
  
• Page 2: blowup of 4850 MHz ripple dps 1 polB
• Top: this shows the ratio of bandPass calibrator on/off
• Bottom: ration of srcOnSpc/srcOffSpc.
• polB is strongest in srcOn/Off 
  
• you can see a little of it in polA
• The period of the ripple is about 10.5 MHz. (about 15 meters in air).
• Page 3: median spectral power vs time for the 300 1 second samples on and off source.
• Top on Source
• bottom Off source.
• PolA seems to wonder more on source than polB and off source.
• PolA was previously giving us stability problems (before the elbow in the dewar was replaced).
• The ripple problem is in polB so whatever the variation is, it isn't causing the ripple.

Summary 04nov12:

• 1 mock box had trouble with bit flips (b1s1g1,pdevs-108, polA). It was replaced 05nov12.
• 1 mock box  (b5s1g1) showed 10 MHz ripple in 1 dps pattern polB
  
• It was mainly in the onSource data
• It did not repeat during the next  2 scans,
• cband polA may be wandering around a bit more than polB (either gain or Tsys).