2023-02-07
OMC DCPD transimpedance amplifier dark noise.

Physical Setup:
IMC to OFFLINE so that no light, guaranteed is hitting the DCPDs.
	by 08:26:00 PST, 16:28:00 UTC
Using new BNC interface on the front of the D2200215 whitening chassis (awesome!)

BNC to SR785 (plugged into the wall, for better or worse),
CH1 A = A+
CH1 B = A-
CH2 A = B+
CH2 B = B-
... but at least with the new system, the shields of the BNC are connected to chassis GND.

SR785 Setup

Display Options
	Display: Live
	Format: Dual
	X-axis: Log
	RPM Frequency: OFF
	Grid: ON
	Grid Div: 10
	Phase Suppress: 0.0e+00
	d/dx window (%): 0.5

Display Setup
	UPPER DISPLAY
	Measure Group: FFT
	Measurement: FFT1 (for channel 1)
	View: Log Mag (really, log amplitude)
	Units: Vrms/rtHz
		dB Units: OFF
		Pk Units: rms
		PSD Units: ON
		Phase Units: (deg)
		dBm Ref Imped: 50

	LOWER DISPLAY
	Measure Group: FFT
	Measurement: FFT2 (for channel 2)
	View: Log Mag (really, log amplitude)
	Units: Vrms/rtHz
		dB Units: OFF
		Pk Units: rms
		PSD Units: ON
		Phase Units: (deg)
		dBm Ref Imped: 50

Freq (Three Spans used)
	Started with
	Span: 400 Hz
	Line Width: 500 mHz
	Acq. Time: 2 sec
	FFT Lines 800
	Base Freq: 102.4 kHz
	Start: 0 Hz
	Center Freq.: 200 Hz
	End Freq: 400 Hz

	Then for the 4 Hz to 3.6 kHz band, just hit "Span Up" three times.
	Then for the 32 Hz to 25.6 kHz band, just hit "Span Up" three more times.

Input
	Source: Analog
	Analyzer Config: Dual
	Input Config ((for BOTH CH1 and CH2)
		Input Mode: A-B
		CH2 Coupling: AC
		CH2 Input Range: -50 dBVpk
		AA Filter: ON
		A-Wt Filter: OFF
		Ch2 Auto Range: Up Only (though auto range was OFF)

Average
	Compute Avgs: Yes
	Averaging Type: Linear/ Fix Len
	# Avgs: 50
	Display Avg: RMS
	Time Record Incr.: 100%
	(All else as default)

Output
	Hard Copy Button: ASCII Dump
	Destination: Disk File