8:45a start. Confirmed with Operator that IMC is offline, so no light's on the DCPDs.

8:45 - 8:55a Set up measurement electronics using S2300003.

Physical setup
Measuring transimpedance amplifier by itself.
[1] Actual Board S/N SN 02
[2] In-vac "QPD" Enclosure S/N S2100832
[3] Transimpedance Circuit Schematic D2000592

Measuring using 
[4] D2200215 OMC Whitening Chassis S/N S2300003
[5] D1900068 SR785 Accessory Box S/N S1900266

Following measurement setup defined in 
	/ligo/svncommon/CalSVN/aligocalibration/trunk/Common/Documents/D1900027_CalElectronicsMeasurementDrawings/
    D1900027-v5_aPLUSO4_D2200215-v1_OMCDCPDTransImpAmp_TransImpAmpSetup.pdf

Connecting accessory box SR785 differential drive BNCs to clip-doodles to DB9 breakout pins 1(pos)-6(neg) (with shield connected to chassis GND pin 5), into "From AI/DAC" DB9 port IN THE BACK of the D2200215 chassis.

Be mindful that the BNC back-shells / shields are not touching anything metal, like the rack or chassis as they're fed from the CH1 A & B DUT output of the accessory box through the rack to the AI/DAC input.

Connecting SR785 response comes from the "preamp output monitor" BNC spigots at the front of the D2200215 chassis, "A+" to CH2 A "A-" to CH2 B.


Disconnect SR785 SOURCE from Accessory Box.

Factory Reset the SR785.
System
	Preset
		<ENTER>

Display Setup
	TOP TRACE
	Measure Group: Swept Sine
	Measurement: Freq. Resp
	View: Linear (Magnitude, i.e. not in dB)
	Units: 
		dB Units: OFF
		Pk. Units: OFF
		Phase Units: deg
		dBm. ref impedance: 50

	BOTTOM TRACE
	Measure Group: Swept Sine
	Measurement: Freq. Resp
	View: Phase
	Units:
		dB Units: OFF
		Pk. Units: OFF
		Phase Units: deg
		dBm Ref. Impedance: 50

Freq
	Start: 102.4 kHz 
	Stop: 
		-- 10 Hz Starting for Setup & Confirmation of expected response
		-- 0.1 Hz Final version of Measurement  
	Repeat: Single Shot (don't continuously repeat sweep once done)
	Type: Log (log-spaced frequency vector)
	# of points: 200
	Auto Res.: OFF

Display Options [Both]
	Display: Live
	Format: Dual
	RPM Frequency: OFF
	Grid: ON
	Grid Div: 10
	Phase Suppress: 0.0e+00
	d/dx window (%): 0.5

Source
	Auto Level Ref: OFF
	Amplitude: 4.0 V_pk   << This is key for good low-frequency data!
	Source Ramp Rate 1 V/sec, but
	Source Ramping OFF
	Offset 0.0 V

Input Setup 
	DON'T FORGET :: Auto Offset OFF
	Input Source: Analog
	Input Config:
		CH 1 (Both Channels)
		Mode: A-B (positive legs into A, negative legs into B)
		Coupling: DC	(AC coupling filter is at 0.16 Hz, and we're measuring to 0.1 Hz, so we don't want to be impacted by the response of this filter.)
		AA filter ON
		Wt filter OFF
		Autorange UP ONLY

		Input Range (for 4.0 V source amplitude, 50 ms / 5 cycle integration):
		CH1: +14 dBVpk
		CH2: +16 dBVpk


	DON'T FORGET :: Auto Offset OFF

	Transducer Params: (all as default; unused in this style of measurement)
	Tach Input: (all as default; unused in this style of measurement)
	Playback Config: (all as default; unused in this style of measurement)
	
	DON'T FORGET :: Auto Offset OFF

Average Setup
	Settle Time = 250 ms (250 ms) << This is key for resolving 25 Hz peak!
	Settle Cycles = 2
	Integration Time = 250 ms (250 ms) << This is key for resolving 25 Hz peak!
	Integration Cycles = 7 << This is key for resolving low frequency!

with freq = [0.1 102.4e3] and 200 points, this takes 1.4 kseconds = 23.33 minutes
	(up from 15.24 minutes, mostly because of the 2 settle cycles instead of 1.)
	New crossover frequency is lower 14.95 Hz rather than 29.96 Hz
	Hopefully this helps with the noise at the ~25 Hz resonance.

Output
	Hard Copy Button ASCII Dump
	Bitmap Printer PC X 8 Bit
	Bitmap Area Graphs
	Vector / Plotter PostScript (doesn't matter, unused)
	Destination Disk File
	File Start Number 0

RECONNECT SR785 source to Accessory Box cable.

Make sure "Preamp Test Input Relays" are turned ON
	Diagram shows / says that both can be on during the measurement of each. While I agree it shouldn't matter, since the A and B circuits are different / separate, today it gives me bad joy joy vibes, so start with only DCPD test relay ON.

9:00a ran a quick check with

Freq
	Start: 102.4 kHz 
	Stop: 
		-- 10 Hz Starting for Setup & Confirmation of expected response
	Repeat: Single Shot
	Type: Log (log-spaced frequency vector)
	# of points: 200
	Auto Res.: OFF
and also with
	Start: 10 Hz 
	Stop:  0.1 Hz	Repeat: Single Shot 
	Type: Log (log-spaced frequency vector)
	# of points: 10
	Auto Res.: OFF

to check that I've got the phase right. 
Ran test frequency vector set up again, and phase that matches expectation.

Switching frequency vector back to final measurement configuration.

Freq
	Start: 102.4 kHz 
	Stop: 0.1 Hz 
	Repeat: Single Shot (don't continuously repeat sweep once done)
	Type: Log (log-spaced frequency vector)
	# of points: 200
	Auto Res.: OFF

9:05a started DCPDA measurement!
	1.4 ks / 23.3 minutes.



9:28 measurement done.
	Checking the data.
	Data is 3-5% noisy below 1 Hz.
	I think it's because there's tons of people walking on and over the power cord due to the film crew.

9:36a restarting DCPDA.
	Put up caution sign to make sure no one steps on the power cord.
	Overhead crane is still running around through the low frequency region (it's always the low frequency region 'cause that's what takes the 1.4 ks).
	At least from the cursor, the data looks cleaner.
	Looking for 2.2e-3 V/V varying only at the 0.005e-3 V/V level.
	That's right, we're asking for 5 [uV/V] level precision here. 
	It's kind of ridiculous to expect that, but *we seem to get it* if no one steps on the power cord!

9:59a DCPDA measurement done.
	Checking the data!
	Data looks much better.
	Wow and sad all at the same time.
	But, good to know!

10:01a Switched to DCPD B and started measurement.
	And just FYI, we get to 2 Hz by 10:03a.
	So, it really is 20 minutes spent on the 0.1 to 2 Hz region.

10:24a DCPDB done.
	Checking the data
	Data looks great!
	
10:27a Switched OFF preamps, connected drive signals into DB25 breakout pins 5+ / 18-
10:28a CHA measurement setup started
	so far first two minutes down to 2 Hz look good -- 1.001 V/V across the entire band!
	eeeee so excited. don't jinx it, don't jinx it, don't jinx it...

10:50a CH measurement setup done.
	Checking the data
	Data looks great!
	Noise is at the 1 [V/V] +/-20 [uV/V] level.
	Very good!

10:52a CHB measurement setup started

11:16a CHB measurement setup done
	Checking the data
	Data looks great!

11:18a DB25 ISC_307 reconnected, DCPDs powered back ON.


11:23a Because I have the time, let's check the noise of the measurement.
Leaving the differential amp +/- BNCs connected to CH1 A&B.
	the TIA monitors CHB connected to CH2 A&B

Changing only the following settings:
Display Setup
TOP Display
	Measurement Group : FFT
	Measurement : FFT1
	Units :
		dB Units : OFF
		Pk. Units : RMS
		PSD Units : ON
		Phase Units : deg
		dBm Ref Impedance : 50
BOTTOM Display
	Measurement Group : FFT
	Measurement : FFT2
	Units :
		dB Units : OFF
		Pk. Units : RMS
		PSD Units : ON
		Phase Units : deg
		dBm Ref Impedance : 50

Input setup -- doesn't change, but it's important, so I requote it here:
Input Setup 
	DON'T FORGET :: Auto Offset OFF
	Input Source: Analog
	Input Config:
		CH 1 (Both Channels)
		Mode: A-B (positive legs into A, negative legs into B)
		Coupling: DC	(AC coupling filter is at 0.16 Hz, and we're measuring to 0.1 Hz, so we don't want to be impacted by the response of this filter.)
		AA filter ON
		Wt filter OFF
		Autorange UP ONLY

		Input Range (for 4.0 V source amplitude, 50 ms / 5 cycle integration):
		CH1: +14 dBVpk
		CH2: +16 dBVpk

Average Setup
	Compute Avgs : Yes
	Averaging Type : Linear / Fixed Length
	# Avgs : 25
	Display Avg : RMS
	Time Record Increment: 100%
	More :
		Overload reject OFF
		Trigger Avg Mode : OFF
	Avg Preview 

 


Things to do after we get this measurement suite:
- Send the data to Louis for fitting.
- Create/install new V2A filters for A0 / B0 bank
- Switch over to these filters and accept in SDF
- Run dark offsets for DCPDs -- do we need to?
- Update pydarm parameter file with new super-Nyquist poles and zeros.
- Measure compensation performance with remote DAC driven measurement of TIA*Wh*AntiWh*V2A
	confirm bitterness / flatness
	make sure binary IO still functions

When to push new calibration?

Once IFO is back up, running, (does it need to be thermalized?)
- Measure balance matrix, 
	Remember -- SQZ OFF
	confirm better-ness / flatness
- Install new balance matrix
- Accept Balance Matrix in SDF

Once IFO is thermalized
- grab a new sensing function.