Gabriele Vajente

ILIAS WG1 meeting - Frascati 21.03.06

Noise Analysis Tools Noise Analysis Tools at Virgoat Virgo

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 2

SummarySummary

Tools for monitoring non-stationary noises

Project for an automatic noise budget tool

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 3

Part 1Part 1Non-Stationary Noise MonitorNon-Stationary Noise Monitor

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 4

Non Stationary Noise MonitorNon Stationary Noise Monitor

PurposeMonitor time evolution of noise level in dark fringe

Find correlation with ITF status (alignment, environmental conditions, etc.)

Two partsRunning online: NonStatMoni

Running offline periodically: NonStatMoniOffline

Compute band-limited RMS

Identify lines

Trends

Correlation with ITF status

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 5

NonStatMoni – Band-limited RMSNonStatMoni – Band-limited RMS

Band-limited RMSCompute short spectra (1, 5, 10 s) every 1 s

Output RMS in bands in the main data stream

Fully configurable (channel, spectrum length, etc.)

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 6

NonStatMoni – Lines identification 1NonStatMoni – Lines identification 1

Lines identificationSeparate lines from “background”

Band-limited RMS of background

Frequency, height, SNR of main lines (SNR threshold)

Running only during “locked” periods

Mai

n da

ta s

trea

m

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 7

NonStatMoni – Lines identification 2NonStatMoni – Lines identification 2

In main data stream

Number of lines found

Background band-limited RMS

Frequency, height, SNR for each line found

full RMS

bkg RMS

full RMS

bkg RMS

1.11 kHz

3.88 kHz

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 8

NonStatMoniOffline - SummaryNonStatMoniOffline - Summary

Run periodically, analyze all locks of last period

Output as web pages

Summary of monitored channels

Links to locked periods details

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 9

NonStatMoniOffline – Lock details 1NonStatMoniOffline – Lock details 1

Run periodically, analyze all locks of last period

Output as web pages

Plot of RMS time evolution

Spectrum of RMS evolution

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 10

NonStatMoniOffline – Lock details 2NonStatMoniOffline – Lock details 2

Run periodically, analyze all locks of last period

Output as web pages

Time plot

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 11

NonStatMoniOffline – Lock details 3NonStatMoniOffline – Lock details 3

Run periodically, analyze all locks of last period

Output as web pages

Spectrum plot

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 12

NonStatMoniOffline – Lock details 4NonStatMoniOffline – Lock details 4

Run periodically, analyze all locks of last period

Output as web pages

Coherence table and plots

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 13

Examples of applicationsExamples of applications

Enviromental monitoring (seismometers and microphones)

Airplanes

F. Fidecaro

Monitor band-limited RMS for seismic sensors in all buildings.

One can recover direction and speed

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 14

Correlation with alignment and freq noiseCorrelation with alignment and freq noise

PR yaw BS yaw

NE pitch

Freq. noise

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 15

Modes ring-downModes ring-down

During lock acquisition mirror and violin modes are strongly excited

Extimation of Q factor

3884 Hz

= 106 ± 7 sQ = 1.29 x 106

167 Hz

= 550 ± 20 sQ = 2.89 x 105

Line

hei

ght [

Hz/

rHz]

RM

S b

etw

een

100

and

200

Hz

[Hz/

rHz]

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 16

Part 2Part 2Automatic Noise Budget ProjectAutomatic Noise Budget Project

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 17

Automatic Noise BudgetAutomatic Noise Budget

PurposeTo measure precise projection of technical noises into dark fringe (or other channels)

WhyTo precisely identify the contribution of the most important noise sources

To track the evolution of noise couplings

To gain data to model noise couplings

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 18

MethodMethod

1. Measure transfer function from error/correction signal to dark fringe with noise injection

2. Project the normal noise using the measured TF

Interferometer

Control loop

Dar

k fr

inge

NOISE

NOISE

SINGLE CAVITY

SINGLE CAVITY

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 19

TF measurement methodsTF measurement methods

Full measurementBy injecting (white) noise into each channel separatelySlow (at least 60s per channel)Precise measurements of TFsMight cause saturation problems or unlocksNeed to “shape” the noise

Fast measurementMeasure 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 measurementInject 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

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 20

Technical noise sourcesTechnical 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

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 21

Outcomes of the toolOutcomes of the tool

Noise budgets

Transfer functions

Using permanent calibration linesTrack time evolution of noise couplings and ITF performances

Better identify non-stationarity sources

ILIAS WG1 meeting, Frascati 21.03.06 – Gabriele Vajente 22

ConclusionsConclusions

Non-stationary MonitorDeveloped and tested, already running onlineMonitor dark fringe and 25 environmental channelsAutomatic generate summary web pages

Automatic Noise BudgetClear projectAlready tested some noise injection in single cavity configuration