40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log  Not logged in ELOG logo
Entry  Tue May 14 01:56:20 2013, Jenne, Update, Green Locking, Xend Green tweaked 
    Reply  Tue May 14 02:19:13 2013, Koji, Update, Green Locking, Xend Green tweaked 
    Reply  Tue May 21 18:18:23 2013, Manasa, Update, Green Locking, Xend Green aligned 
       Reply  Tue May 21 23:29:57 2013, Manasa, Update, Green Locking, Xend Green aligned 
          Reply  Tue May 28 19:35:17 2013, Manasa, Update, Green Locking, Still searching for the X green beat note 
             Reply  Thu May 30 01:02:41 2013, Manasa, Update, Green Locking, Found it! IMG_0598.JPGIMG_0599.JPG
                Reply  Mon Jun 3 21:09:55 2013, Manasa, Update, Green Locking, X green beatnote through beatbox IMG_0608.JPG
                   Reply  Tue Jun 11 22:16:56 2013, Manasa, Summary, Green Locking, ALS for X arm 
                      Reply  Thu Jun 13 22:31:12 2013, Manasa, Summary, Green Locking, X arm ALS IMG_0659.JPGALS_stabilized_13June2013.png
                         Reply  Fri Jun 14 07:06:19 2013, Koji, Summary, Green Locking, X arm ALS 
Message ID: 8703     Entry time: Thu Jun 13 22:31:12 2013     In reply to: 8694     Reply to this: 8708
Author: Manasa 
Type: Summary 
Category: Green Locking 
Subject: X arm ALS 

Stabilized ALS and beat frequency sweep realized.

Procedure:

1. Enable appropriate filter modules and set appropriate servo gains.

Servo module

Filters Gain
C1:ALS-BEATX_FINE_I   FM2 FM3 1.0
C1:ALS-BEATX_FINE_Q FM2 FM3 1.0
C1:ALS-BEATX_FINE_PHASE FM1   300.0
C1:ALS-BEATX_FINE_OFFSET - 1.0
C1:ALS-XARM FM4 FM5 -0.25
C1:ALS-ETMX - 1.0


2. Clear history of C1:ALS-BEATX_FINE_PHASE

3. Enable the servo loop. I had set limits on the servo loop and ramp time for gain switching so that I don't kick the ETMY hard.
Gains were decided such that the error signal C1:ALS-BEATX_FINE_PHASE_OUT was minimized.

4. Beat frequency sweep is realized by stepping up on C1:ALS-BEATX_FINE_OFFSET_OFFSET (from 0 to 2100 in this case).

Video1 shows the difference that can be seen at the RF spectrum analyzer when ALS is enabled.

Video2 shows the beat frequency sweep as seen on the spectrum analyzer.

I could not get 'getdata' to work as I wanted. So I have attached the error signal trend before and after the ALS servo loop is enabled.

Thank you Jenne for helping retrieve more sensible data!

More info:
The beat note is very strong and we can clearly see its harmonics as well. Attached is the picture showing the several harmonics.
________________________________
Peak frequency(MHz)    Power(dBm)
________________________________
 47                                    -2.77
 93.5                                -27.56
 139                                 -32.75
 185.4                              -45.64
 231.9                              -57.10
 278.4                              -59.42
________________________________

To do:
1. Obtain IR resonance.
2. Check the digital anti-whitening filter after the beatbox.
3. The effect of the harmonics should be figured out.
4. Write scripts to enable ALS and findIRresonance.

Attachment 1: IMG_0659.JPG  6.824 MB  Uploaded Thu Jun 13 23:32:51 2013  | Hide | Hide all
IMG_0659.JPG
Attachment 2: ALS_stabilized_13June2013.png  131 kB  Uploaded Thu Jun 13 23:50:19 2013  | Hide | Hide all
ALS_stabilized_13June2013.png
ELOG V3.1.3-