Introduction

The line interference can be described as a sum of quasi-monochromatic signal m(t) and stochastic noise n(t) associated with the line The signal m(t) can be regarded as a random process, produced by random modulation of a harmonic oscillation of frequency w
m(t) = a(t) cos(wt + p(t)), where amplitude a(t) and phase p(t) vary in time, in accordance with some statistical low. To qualify this process as a quasi-monochromatic signal the bandwidth of the modulation should be very small compare to the carrier frequency w. The purpose of the task is to study the line noise in the GW channel, e.g quantify the parameters of quasi-monochromatic signal and stochastic noise, including study of correlations and transients associated with lines.

Preliminary Plan

Study the line noise sources including:

60Hz line and it's harmonics
violin modes
mirror vibration modes
other sources, which line noise may be present in the GW channel

The line noise characterization is similar for different sources and includes
the following studies:

measure the line fundamental frequency w and check it's stability.
correlations between harmonics (time-frequency plots)

quantify the amplitude and phase as a function of time

study the statistical properties of a(t) and p(t) (e.g. Rayleigh behavior for violin lines)

estimate stochastic noise n(t)

study correlations with environmental channels and IFO channels

60Hz harmonics - magnetometers, 60Hz line voltage
violin and mirror modes - sismic and control channels

study transients associated with the lines

rate and strength of transients for 60Hz lines
ringdown after the lock for violin and mirror vibration modes
....

software tools:

Multitaper Line Removal
Coherent Line Removal
Quasi-Monochromatic Line Removal
Kalman Filtering
Adaptive Line Removal (?)
Power Line Monitor (?)

questions/concerns:

Add channels EY-V1,EY-V2,EX-V1,EX-V2,LVEA-V1,LVEA-V1,LVEA-V3 into the list .
The software tools listed above are designed to remove lines that is not actually a purpose of the Line Noise Investigation. To adapt them for line monitoring and characterization, the LNI group may need help from the tool developers. Also, the LNI group need help from the developers to install and run the tools on data.
How to deliver data to the LNI group members?.

resources:

Disk space to store the test samples. (5 GB ?)

Last update: November 20, 2000
Klimenko Sergey