Texas Instruments MSP430x4xx - Manual (Page 488)

Scan IF Operation
24-28 Scan IF
24.2.6 Using the Scan IF with LC Sensors
Systems with LC sensors use a disk that is partially covered with a damping
material to measure rotation. Rotation is measured with LC sensors by
exciting the sensors and observing the resulting oscillation. The oscillation is
either damped or un-damped by the rotating disk. The oscillation is always
decaying because of energy losses but it decays faster when the damping
material on the disk is within the field of the LC sensor, as shown in
Figure 24−14. The LC oscillations can be measured with the oscillation test or
the envelope test.
Figure 24−14. LC Sensor Oscillations
Damped
Undamped
Envelope
Time
AV
CC
/2