This morning, from about 7:40 to 8:10 UTC we performed a measurement of the magnetic noise in the rack hosting the environmental monitoring electronics in DAQR, in different conditions:
- at about 7:42 UTC the probe was placed in the selected position, between the ENV-NI and ENV-BS slow monitor modules;
-at 7:51 UTC all the envmon electronics in the rack was switched off;
-at 8:00 the two PCB amplifiers were switched on;
-at 8:02 the Nexus amplifier was switched on;
-at 8:04 the slow monitoring modules far from the magnetic probes (ENV-IB,PR,DT,SR,WI) were switched on
-at 8:06 the remaining modules were switched on.
In figure 1 the evolution of the measurement is shown, while in figure 2 the spectra of the noise measured in different period of the test are reported: magenta=All OFF, cyan=PCB and Nexus ON, green=Far modules ON, blue=All ON.
It is evident that the measurement is mainly dependent from the distance between the probes and the source, indeed about a factor 10 of noise increase is observed between the two last conditions.