Total power and spectrum ratios ADC / filtersnap / HPC spectra
Identical ratios for varying input power
Do this with noise source on inputs to ADCs, inputs to VEGAS IF Modules, and with real (converter rack) signals, with these Teed off to DCR.
Using the new noise source, 300MHz highpass filter, amplifier, attenuator and 8-way splitter
Details
Set up at 8:00am, Jason connects noise source to ADCs
Set up lbw_gain. From Randy, empirically the digital filter requires a gain of 5.664 to get -20dBFS into each of real and imag separately, for a -20dBFS input.
So, set lbw_gain to 2**16 (unity in BOF) * 2**8 (Ray correction for old config_tool)*5.664
Output power for filtersnap will be 3dB above input power, since real and imag powers are summed together.
Mode 4 - noise source to ADC input
bank_gain_mode4_cband_nocal
archivist
setValues with 5.664 * 2**24
Attenuator setting of 0dB corresponds to ~ -15.8dBFS. filtersnap goes to around -12.5 dBFS - close enough
Change attenuator by 8dB seems to change ADC value by 8dB also - is this what I saw before? Start from attenuation of 0dB, and set in powers of 3dB.
Run 60 second tracks
Scans 1-6 = 0,3,6,9,12,15 dB attenuation
quick exploration with GBTIDL; everything seems to be working perfectly!
Mode 1 - noise source to ADC input
bank_gain_mode1_cband_nocal
archivist
SetValues is irrelevant
Scans 7-12 = 0,3,6,9,12,15 dB attenuation
Looks sensible, but slightly off, e.g. ratio between 7 and 9 looks like 3.5 (should be 3.98) = 5.44dB iso 6dB
Mode 4 - noise source to VEGAS Analog IF input, and VEGAS IF monitor output to DCR
Need to remove the amplifier from the noise source, as the VEGAS IF module has gain. Nominal -20dBFS corresponds to 18dB on the attenuator
bank_gain_mode4_cband_nocal
archivist
setValues with 5.664 * 2**24
Manually set up the Analog Filter Rack and the DCR to send the VEGAS IF module monitor output to the DCR
On Analog Filter Rack, set 1.6 GHz samplers to have SGfilters set to "external". This is where Galen will hook in.
Can monitor at All Samplers / SG Power
Outputs go to DCR A9 - A16
Do a test scan to see whether DCR samplers will start toggling. Add DCR to Scan Coordinator
Note, Bank H pol 2 (J16) seems to have a dodgy connector out of VEGAS IF module to ADCs; value was jumping around until Galen poked at it.
Scan 13 60 sec track. No sign of DCR values updating..
DCR FITS file has no rows...
Try a quick pointing scan - scan 14
Turns out it seems like DCR has to be the switching signal master, even for no switching
Do all of the above setup. Set DCR to 1 sec integratgions, DCR as master, no switching. Include in scan coordinator
attenuator at 18 dB gives ~ -20dBFS. Ratio of ADC to filtersnap is now around 6dB (filternsap = -14dB) - presumably because of different passband
or something? I don't really understand this...
Scan 15 12 dB attenuation. DCR is now around 22 counts. DCR FITS file is around 4.39e+06, VEGAS is around 1.5e+11
Scan 16 15dB attenuation. DCR is now around 12 counts. DCR FITS file is around, VEGAS is around 2.17e+06 0.75e+11
Scan 17,18,19,20 = 18,21,24,27dB attenuation
switch to mode 1
Mode 1 - noise source to VEGAS Analog IF input, and VEGAS IF monitor output to DCR
bank_gain_mode1_cband_nocal
archivist
SetValues is irrelevant
re-include DCR
Scans 21-26, attenuations 12 - 27dB
Mode 1 - C-band - receiver IF to VEGAS with VEGAS IF module monitor output to DCR
bank_gain_mode1_cband_nocal
archivist
balance - to get IF input levels around -20 dBFS
SetValues is now irrelevant
Not getting the values I expect in the IF Manager - for example, IF Manager is now showing 800MHz filter.... resend and everything is ok.
Suspect CLEO IF Manager may not be updating somehow?
Balance to -15dB
DCR now showing ~ 26V
Scan 27 -15dB into VEGAS ADCs. But DCR didn't read any data... Somehow SSS got switched back to VEGAS!
Scan 28 - 15dB
Scan 29 - 18dB - approx factor of two difference from 28, not exact as converter rack attenuation change is not exact
Scans 30-32, -21,-24,-27 dB
Scan 32, only 4 of 8 channels seemed to balance properly... Balance manually
Scan 33 -27dB
Mode 4 - C-band receiver IF to VEGAS with VEGAS IF module monitor output to DCR
Config tool puts in a 320MHz filter, so system is being overdriven to get ADC to -20dBFS. Need a smaller lbw_gain.
By experiment, need a value of 2 * sqrt(2) smaller - don't really understand this value.
Scan 34 -15dB into VEGAS ADCs.
VEGAS Bank H aborted due to invalid data..., twice...Turn Bank H off and on again. Doesn't cure it. Call Ray. Now it is worse... then cures itself
Scan 39 -15dB - DCR got no data, not SS Master
Scan 40 -15dB Now we are in business.
Scans 41 - 44 -18, -21, -24, -27 dB. Ratio of scans is huge! What on earth is going on here....?
Mode 1 - X-band receiver IF to VEGAS with VEGAS IF module monitor output to DCR
bank_gain_mode1_xband_nocal
Archivist
can't balance to -15dB again in one input, but proceed anyway.
SetValues is irrelevant
Scans 45-49: -15 - -27 dB
Mode 4 - X-band receiver IF to VEGAS with VEGAS IF module monitor output to DCR
bank_gain_mode4_xband_nocal
archivist
balance to -15dB fails, -18dB is close; start from here.
need same value of lbw_gain as for C-band (not too surprising)
Scan 50-53, -18 - -27dB
Mode 1 - X-band, tp with cal with DCR running also.
band_gain_mode1_xband - high Tcal
archivist
balance -20dB
tell VEGAS that the DCR is the switching signal master
DCR is not happy. Configure for DCR, then add VEGAS. See if that works? Not sure how to set it up...
Scan 55 configure with bank_gain_mode4_xband_dcr. Then add VEGAS back in. Need to check IF filters. Runs at least, takes data
Scan 56 low tcal
Mode 4 - X-band, tp with cal with DCR running also.
Configure VEGAS with bank_gain_mode4_xband, then dcr with above