40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  PSL  Not logged in ELOG logo
Message ID: 1524     Entry time: Thu Sep 18 22:13:35 2014
Author: Evan 
Type: DailyProgress 
Category: RFAM 
Subject: RAM coherence 

I used the auxiliary 1811 as an out-of-loop RAM monitor. The RF from the 1811 is mixed with the PDH LO, and then low-passed at 1.9 MHz.

I'm not sure about the RAM calibration here. I took the raw spectrum (in V/rtHz), multiplied by 10^(4/20) (assuming 4 dB conversion loss in the mixer), then divided by the measured dc voltage (about 20 mV), then divided by 40 (because of the different dc/ac tranimpedances).

Anyway, the point is that the 200 Hz hump we see in the beat seems to be from the north RAM.

Attachment 1: ramCoherence.zip  73 kB
Attachment 2: ramCoherence.pdf  206 kB  Uploaded Thu Sep 18 23:28:11 2014  | Hide | Hide all
ramCoherence.pdf
ELOG V3.1.3-