During the test injection, the sensor with the best Signal to Noise Ratio is ENV_CEB_ELECTRIC, followed by ENV_CEB_GROUND_CURR_MON and ENV_CEB_GROUND_MAG.

The magnetometers near the towers all detect the Comb signal, in some cases up to three orders of magnitude above the noise floor.

This is expected: the cable running from the TIRA BAA-120W power amplifier output toward the NI suspension rack and, in parallel, toward the SR tower forms a large loop, which generates a significant magnetic field.

This must be considered when evaluating the effect in Hrec: coupling may arise from the magnetic field rather than from currents in the grounding connections, as the field can act directly on the mirror magnets.

When only real ground-current flow is present, this effect should be absent or strongly suppressed, since no large loop is formed.