1 / 22

Noise Analysis Tools at Virgo

Noise Analysis Tools at Virgo. Summary. Tools for monitoring non-stationary noises Project for an automatic noise budget tool. Part 1 Non-Stationary Noise Monitor. Compute band-limited RMS Identify lines. Trends Correlation with ITF status. Non Stationary Noise Monitor. Purpose

arden-preston
Download Presentation

Noise Analysis Tools at Virgo

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Noise Analysis Tools at Virgo

  2. Summary • Tools for monitoring non-stationary noises • Project for an automatic noise budget tool

  3. Part 1Non-Stationary Noise Monitor

  4. Compute band-limited RMS • Identify lines • Trends • Correlation with ITF status Non Stationary Noise Monitor • Purpose • Monitor time evolution of noise level in dark fringe • Find correlation with ITF status (alignment, environmental conditions, etc.) • Two parts • Running online: NonStatMoni • Running offline periodically: NonStatMoniOffline

  5. NonStatMoni – Band-limited RMS • Band-limited RMS • Compute short spectra (1, 5, 10 s) every 1 s • Output RMS in bands in the main data stream • Fully configurable (channel, spectrum length, etc.)

  6. Main data stream NonStatMoni – Lines identification 1 • Lines identification • Separate lines from “background” • Band-limited RMS of background • Frequency, height, SNR of main lines (SNR threshold) • Running only during “locked” periods

  7. NonStatMoni – Lines identification 2 • In main data stream • Number of lines found • Background band-limited RMS • Frequency, height, SNR for each line found full RMS full RMS bkg RMS bkg RMS 1.11 kHz 3.88 kHz

  8. Summary of monitored channels Links to locked periods details NonStatMoniOffline - Summary • Run periodically, analyze all locks of last period • Output as web pages

  9. Plot of RMS time evolution Spectrum of RMS evolution NonStatMoniOffline – Lock details 1 • Run periodically, analyze all locks of last period • Output as web pages

  10. NonStatMoniOffline – Lock details 2 • Run periodically, analyze all locks of last period • Output as web pages Time plot

  11. NonStatMoniOffline – Lock details 3 • Run periodically, analyze all locks of last period • Output as web pages Spectrum plot

  12. NonStatMoniOffline – Lock details 4 • Run periodically, analyze all locks of last period • Output as web pages Coherence table and plots

  13. Examples of applications • Enviromental monitoring (seismometers and microphones) • Airplanes Monitor band-limited RMS for seismic sensors in all buildings. One can recover direction and speed F. Fidecaro

  14. Correlation with alignment and freq noise PR yaw BS yaw NE pitch Freq. noise

  15. Modes ring-down • During lock acquisition mirror and violin modes are strongly excited • Extimation of Q factor 3884 Hzt = 106 ± 7 sQ = 1.29 x 106 167 Hzt = 550 ± 20 sQ = 2.89 x 105 Line height [Hz/rHz] RMS between 100 and 200 Hz [Hz/rHz]

  16. Part 2Automatic Noise Budget Project

  17. Automatic Noise Budget • Purpose • To measure precise projection of technical noises into dark fringe (or other channels) • Why • To precisely identify the contribution of the most important noise sources • To track the evolution of noise couplings • To gain data to model noise couplings

  18. Method • Measure transfer function from error/correction signal to dark fringe with noise injection • Project the normal noise using the measured TF SINGLE CAVITY NOISE Interferometer Dark fringe NOISE SINGLE CAVITY Control loop

  19. Full measurement By injecting (white) noise into each channel separately Slow (at least 60s per channel) Precise measurements of TFs Might cause saturation problems or unlocks Need to “shape” the noise TF measurement methods • Fast measurement • Measure once the TFs with full method • Use calibration lines to correct their overall gain • Fast (can inject lots of lines simultaneously) • Might be not very precise • Can easily track time evolution • Lines measurement • Inject several (10) lines for each d.o.f. at different frequencies • Need to know the approximate shape of the TF • Faster than full, more accurate than fast • Less saturation problems

  20. Technical noise sources • Control noises • Longitudinal (DARM, MICH, PRCL) 3 dof • Angular (PR, BS, NI, NE, WI, WE tx & ty) 12 dof • Input beam noises • Frequency noise 1 dof • Laser power noise 1 dof • Input beam jitter (translation & tilt) 4 dof • IMC controls (angular and longitudinal) 3 dof • Modelled noises • Shot noise (need only power measurements) • Dark noise • DAC noise • Phase noise

  21. Outcomes of the tool • Noise budgets • Transfer functions • Using permanent calibration lines • Track time evolution of noise couplings and ITF performances • Better identify non-stationarity sources

  22. Conclusions • Non-stationary Monitor • Developed and tested, already running online • Monitor dark fringe and 25 environmental channels • Automatic generate summary web pages • Automatic Noise Budget • Clear project • Already tested some noise injection in single cavity configuration

More Related