Displaying report 1-1 of 1.
Reports until 19:44, Wednesday 27 March 2019
H1 DetChar
jenne.driggers@LIGO.ORG - posted 19:44, Wednesday 27 March 2019 - last comment - 11:17, Thursday 28 March 2019(47954)
IMC VCO sweep tonight

As suggested by alog 47939, I've written a script that will slowly sweep the IMC VCO while we're in Observe.  Patrick has instructions on how to run it, and he (or the Owl operator) will alog the times that the sweep has run.

Comments related to this report
patrick.thomas@LIGO.ORG - 23:17, Wednesday 27 March 2019 (47959)
Link 

06:16 UTC Started script as controls on zotws3.
jeffrey.bartlett@LIGO.ORG - 03:34, Thursday 28 March 2019 (47965)DetChar
Link

The VCO Sweep ended on 03/28/2019 at 10:22:05.349809 (UTC), 03:22:05.349809 (PT).

andrew.lundgren@LIGO.ORG - 05:11, Thursday 28 March 2019 (47970)DetChar, ISC
Link 

Here's a quick analysis, we'll do a more thorough one later. The attached plot shows glitches in DARM as a function of VCO frequency. There are many different lines that give beatnotes. The widest clean area is around 78.8 Mhz, with 79.75 MHz second best. It would be best to spend another hour doing more restricted sweeps over any proposed areas we plan to use.

If the calibration from the VCO tuning offset to the frequency is needed, Detchar can fit this data and provide that.

(Edit: New plot uploaded without the axis labels cut of.)
Images attached to this comment
daniel.sigg@LIGO.ORG - 09:45, Thursday 28 March 2019 (47977)
Link

Exact sweep times for the ramp from +5V to -5V:

  • Start: 3/28/19 07:32:45 UTC / GPS 1237793583
  • Duration: 10107 sec
  • Stop: 3/28/19 10:21:12 UTC / GPS 1237803690
  • VCO tune offset channel: H1:IMC-VCO_TUNEOFS
  • VCO frequency channel: H1:IMC-VCO_FREQUENCY
daniel.sigg@LIGO.ORG - 11:17, Thursday 28 March 2019 (47980)
Link

Plot 1 shows Frequency against tune voltage. The VCO frequency is offset by 79.2 MHz.

Plot 2 shows a histogram of the VCO frequencies during ramping in 5 kHz bins. Looks like we covered the full range.

The VCO frequency can be estimated by VCO frequency = 79.2 MHz – 44 kHz + v 140.3 kHz – v3 0.4447 kHz, with v the tune voltage.

For 78.8 MHz we get –2.59 V, and for 79.75 MHz we get +4.53 V. The full range of this VCO is from 77.9 MHz to 80.4 MHz. With the full tune voltage range of ±10 V, we can access frequencies from ~78.0 MHz to ~80.3 MHz.

Non-image files attached to this comment
Displaying report 1-1 of 1.