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)
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)
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.
The VCO Sweep ended on 03/28/2019 at 10:22:05.349809 (UTC), 03:22:05.349809 (PT).
Exact sweep times for the ramp from +5V to -5V:
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.