Test of acoustic injection with the ENV_MAIN node

We did several attempts of injecting colored (8-2000 Hz) acoustic noise in the CEB trying to eliminate the problem of the louder spike at the start of the injection.

First we used the automated node. Il seems that the spike appears when the volume of the injected noise goes above 0.001 V (despite each time we manually issued a "reload filter" and "enable filter"). Figure 1 shows one example with the spike (volume at 0.004 V, this one caused an unlock of the ITF). Figure 2 shows one example without the spike (volume at 0.0004V. This is too low for our purposes).

Then we did some trial with the ENVnoise process (but we set off the loudspeaker to be safe). In this case we could inject up to 0.004 V without the spike. This is shown in Figure 3: the two tests done between 10:25 and 10:45 UTC are with a volume of 0.004V and there is no spike.

Test and actual injection of magnetic lines in the range 2 - 25 Hz in CEB, using the ENV_MAIN node

After some tests, at 14:15 UTC we ran the ENV_MAIN node to inject the following magnetic lines with the CEB large coil (in a sequence):

•   2.5 Hz, 3.5 Hz, 4.5 Hz, 5.6 Hz, 6.5 Hz, 7.5 Hz, 9.0 Hz, 10.6 Hz (each for 900 s)
•  12.0 Hz, 13.6 Hz, 15.0 Hz, 19.0 Hz, 22.0 Hz, 24.0 Hz (each for 600s)

The run should end at about 17:15 UTC. The gps of the single injections will be written in the file

/virgoData/NoiseInjections/MagneticInjectionsO4/output/MagneticLine_NOISE_MAG_CEB-1387894545.txt

Indeed it looks that the lines are detected in Hrec. Figure 4 shows the example of the 2.5 Hz line.