PRMI Noise budget
Measurements
- 7/Mar/2012 by KI
Sensor in use
- AS55_Q for MIHC
Gain of whitening filter = 30 dB for both the I and Q.
Demodulation phase = 5.4 deg (at which the I signal doesn't respond to the Michelson displacement).
- ~ very tiny DC light is on the RFPD
- REFL33_I for PRCL
Gain of whitening filter = 42 dB for both the I and Q.
- clear
DC light
port name
DC power [mW]
AS55
~0
REFL
1.9 mW
Sidebands
- The values noted here were estimated from the OSAs at the AS and REFL ports.
Optical gains
Parameters
description
values
notes
Estimated Optical gain
80 uW/m
Measured pk-pk Michelson error signal
1000 counts
Michelson was freely swinging
Raw optical gain
5.9052 x10^9 [counts/meter]
= 4 * pi / lambda * (pk value of the error signal)
Conversion loss of mixer
6.5 dB
from the spec sheet of JMS-1H
ADC conversion
1638.4 counts / V
16 bit, +/-20 V
Trans impedance at 55 MHz
556.3 Ohm
Responsibity of diodes
0.8 [A/W]
from the spec sheet of CS3102
Attenuation in the AS path
Servo filters
- UGF = 55 Hz
- Only FM5 (10:1000) was activated.
- G = -2
- No limiter in the digital path.
- Feeding the signal back to BS.
- Dewhitening filters in BS are ON.
- Assumption : BS actuator has a pole at 1 Hz with Q = 5
- Time delay = (without considering the effects from the analog circuits and the down sampleing filters.)
RAM effects
- There is a big RAM signal in the I signal. The signals float from -100 counts to 0 counts as the Michelson freely swings.
- The amount of the RAM looks changing as a function of time.
- The Q signal looks having not so much RAM effect.