TGBT14A_912_86 - VEGAS Bank Discrepancy Problems
Goals
- Perform the definitive "with DCR" tests
Setup
- Inputs to either ADCs directly, or VEGAS Analog IF module inputs
- connect power meter to E1 splitter cable (ADC inputs) or Analog IF monitor output for EI
- terminate E1 ADC when there is no input
- Configure the system as follows:
- Configure the IF Rack so that the two polarizations of the X-band receiver are connected to two low DCR ports (I don't know what numbers they will be now, but should be in range 1-8)
- Connect seven of the VEGAS Analog IF module monitor points for banks E through H to DCR ports 9-15
- Connect E0 (i.e. first pol) one of the VEGAS Analog IF module monitor points to the power meter. .
- Configure VEGAS for alternately Mode 1 and 4.
- Take a series of Off/On Low/On High/Off/On Low/On High/Off total power no cal data (so single phase), switching noise source on and off manually between scans.
- Recorded data will be:
- Receiver RF power straight into DCR (first two ports)
- VEGAS Analog IF monitor outputs into DCR (next eight ports)
- VEGAS ADC measpwrs
- VEGAS filtersnap_nogain measpwrs (from filtersnap_nopgain sampler)
- VEGAS filtersnap measpwrs (from filtersnap samplers)
- VEGAS spectra. Convert VEGAS spectra into total power by summing over channels, and normalizing by some useful number.
- For each automated data source, for each scan, form mean and std deviation for the ~ 60 good 1sec samples (ignoring obviously discrepant values).
- power meter reading, plus error in reading, will have to be entered by hand in some convenient way (maybe CSV file with scan, power, error).
- For a given pair of input scans, for the RF power into the DCR (two values), and all other quantities (eight values; can just be labelled 1 through 8 on X-axis) plot:
- "On" value with errors
- "Off value with errors
- "On-Off" with propagated errors
- "Off/(On-off)" with propagated errors
- Repeat for Mode 1 and Mode 4
Details
X-band RF / IF tests
- VEGAS J16 (H2) has a dodgy cable for these tests.
- 10:30am. Galen connects up IF monitor outputs. Module E1 is connected to power meter.
- run bank_gain_mode4_xband_nocal
- run balance. Three inputs won't balance - why not?
- have an LO power level error from X-band receiver. Manually increase LO power level.
- System still won't balance. Problem seems to be in Converter Rack (attenuators are at zero). Why is this?
- Try swapping around between modes and balancing; things seem to improve a bit, not sure why (I think I changed receivers...) *
- Setup
- Archivist
- bank_gain_mode4_xband_dcrIF - sets up DCR channels 2 and 4 to connect straight to Rx, 1280MHz filter in IF rack. DCR power is 5.75V for channel 2. Hope this stays this way.
- bank_gain_mode4_xband_vegas_dcr_config check what receiver is selected
- DCR banks 2 and 4 seem the same - need to turn them back on manually.
- DCR channel 9 has no input (as expected); remainder are around 10v.
- Power meet reads -2.23926857E+001 dBm).
- Manually tweak converter rack attenuators to:
9 3.25
10 2.125
11 0.0 - VEGAS at -22.2dBFS
12 4.0
13 6.25
14 10.0
15 4.75
16 0 - - VEGAS read -25dBFS
- Try toggling noise source. Do all values change as expected?
- All values change. Pol 1 change seems much stronger than Pol 2 (1.5dB c.f. 0.5dB). Power meter changes from -22.36 to -20.90
- DCR port 2 changes from ~5 to ~ 8
- Toggle back and run a scan
- scan 1 60 sec scan, no noise - Aborts, Antenna in scan coordinator
- scan 2. Power meter -22.345, -22.320, -22.3245, -22.338. Seems stable to around 0.01dB. All data looks good. Go to lunch at this point.
- Back from lunch - everything still looks good. Run a series of of/lo/hi scans
scan noise power meter ( /10)
3 off -2.2430
4 lo -2.2232
5 hi -2.1001
6 off -2.2425
7 lo -2.2219
8 hi -2.0945
9 off -2.2379
10 lo -2.2219
11 hi -2.0962
12 off -2.2382
- Manually set Converter Rack attenuators, so VEGAS power levels are as close as possible to -17dBFS (can't reach any higher).
- Remove 3dB of attenuation from Converter rack - doesn't appear exactly right...
scan noise power meter ( /10)
13 off -1.9472
14 lo -1.9198
15 hi -1.7784
16 off -1.9181
17 lo -1.8959
18 hi -1.7673
19 off -1.8938
20 lo -1.8211
21 hi -1.7575
22 off -1.8759
- Set converter racks to -23dBFS (all but H2 make it)
scan noise power meter ( /10)
23 off -2.5360
24 lo -2.5323
25 hi -2.4028
26 off -2.5579
27 lo -2.5426
28 hi -2.4238
29 off -2.5646
30 lo -2.5458
31 hi -2.4214
32 off -2.5502
- Reconfigure as close as possible to -20dBFS
- Manually set up both VEGAS and DCR for switching (1 sec swper), and run scans with low and high cal diodes.
- Scan 33 - low power
- Scan 34 - high power
- scan 35 - low power
- scan 36 - high power
- Scan 37 - low power
- Scan 38 - high power
Noise source Into VEGAS IF tests
- CLEO hangs up on me, Bank A Accessor seems to have died, then comes back...
- Connect E0 line of splitter to noise source, to monitor the attenuator levels
- VEGAS H2 (J16) is discrepant from all the rest...
- Configure VEGAS J9 to be connected to no input if possible.... turn off power to laser, and sett attenuator to 31dB. Reads -43dB
- Galen fiddles with J16 VEGAS Analog output to ADC, and manages to get it back - had to replace the cables
- Power meter readings seem slightly out of whack with VEGAS, but continue regardless
- No amplifier on the noise source for this test.
- attenuator setting of 17dB corresponds to VEGAS level of -20dBFS. Run from 0 to 31db in 1 dB steps
- When I change the power level into E2, the power measured by VEGAS in E1 changes!!
- Galen says there is not infinite attenuation between the two channels
Power meter can jump around by ~ 0.1dB, but sometimes 1dB (e.g.
Scan Att Power Meter
39 0 -2.5558
40 1 -2.6564
41 2 -2.7627
42 3 -2.8403
43 4 -2.9447
44 5 -3.0330
45 6 -3.1388
46 7 -3.2448
47 8 -3.3486
48 9 -3.4453
49 10 -3.5519
50 11 -3.6833
51 12 -3.8306
52 13 -3.9781
53 14 -4.0421 -noisy
54 15 -4.2950 - noisy
55 16 varying by 3dB....
56 17
57 18
58 19
59 21 <- Ray called me!
60 20
61 22
62 23
63 24
64 25
65 26
66 27
67 28
68 29
69 30
- Swap noise source to input of ADCs
- amplifier back in
- attenuator of 4 is approx -20dBFS
- Seems like H2 is not connected now.
Scan Att Power Meter
70 0 -5.0910
71 1 -6.0818
72 2 -7.0967
73 3 -7.8520
74 4 -8.8359
75 5 -9.6529
76 6 -1.0634 * 10
77 7 -1.1648
78 8 -1.2629
79 9 -1.3411
80 10 -1.4391
81 11 -1.5411
82 12 -1.6391
83 13 -1.7453
84 14 -1.8438
85 15 -1.9451
86 16 -2.0446
87 17 -2.1529
88 18 -2.2528
89 19 -2.3580
90 20 -2.4579
91 21 -2.5436
92 22 -2.6452
93 23 -2.7562
94 24 -2.8865
95 25 -2.9643 -40dBFS
96 26 -3.0916
97 27 -3.2098 - Jason starts disconnecting here...
Analysis
See:
CICADAGreenBankSpectrometer2015Apr02Analysis
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RichardPrestage - 2015-03-30