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  Sun Mar 28 17:28:26 2010, matt, kiwamu, Update, Green Locking, frequency discriminator for green PLL 6x
    Reply  Mon Mar 29 15:19:33 2010, mevans, Update, Green Locking, frequency discriminator for green PLL 
       Reply  Wed Mar 31 02:57:48 2010, kiwamu, Update, Green Locking, frequency counter for green PLL FCnoise.png
          Reply  Wed Mar 31 12:30:31 2010, rana, Update, Green Locking, frequency counter for green PLL 
          Reply  Thu Apr 1 15:21:12 2010, rana, Update, Green Locking, frequency counter for green PLL 
Message ID: 2737     Entry time: Wed Mar 31 02:57:48 2010     In reply to: 2728     Reply to this: 2741     2751
Author: kiwamu 
Type: Update 
Category: Green Locking 
Subject: frequency counter for green PLL 

Rana found that we had a frequency counter SR620 which might be helpful for lock acquisition of the green phase lock.

It has a response of 100MHz/V up to 350MHz which is wide range and good for our purpose. And it has a noise level of 200Hz/rtHz @ 10Hz which is 1000 times worse than that Matt made (see the entry).

The attached figure is the noise curve measured while I injected a signal of several 100kHz. In fact I made sure that the noise level doesn't depends on the frequency of an input signal.

The black curve represents the noise of the circuit Matt has made, the red curve represents that of SR620.

Attachment 1: FCnoise.png  73 kB  | Show | Show all
ELOG V3.1.3-