What is the Sensor used for Gap Monitoring via IRD7100?

For Gap Monitoring via IRD7100 Machinery Protection Transmitter (MPT) a Non-Contact Eddy Current based Sensor is used. With change in Gap - the DC Voltage Output of the Sensor changes. This change is monitored by IRD7100 and interpreted as Gap.
For example, if a Non-Contact Sensor of Sensitivity 8mV/micron or 8V/mm is used and the Full Scale range of Gap Transmitter IRD7100 is +/- 1mm - then the outputs of IRD7100 vary as shown below:
- When Sensor Nearest to Target - Voltage from Sensor becomes -2 V DC; IRD7100 live display shows -1.00 mm as Gap; 4-20 mA output becomes 4mA; 0-5 V DC output becomes 0V; Reverse Relay Contacts of both Alarm and Trip get energised
- When Sensor at Neutral Position (Zero position) - Voltage from Sensor becomes -10 V DC; IRD7100 live display shows 0.00 mm as Gap; 4-20 mA output becomes 12mA; 0-5 V DC output becomes 2.5V; Relay Contacts are not in energised state
- When Sensor Farthest away from Target - Voltage from Sensor becomes -18 V DC; IRD7100 live display shows +1.00 mm as Gap; 4-20 mA output becomes 20mA; 0-5 V DC output becomes 5V; Forward Relay Contacts of both Alarm and Trip get energised
The Display, 4-20mA, 0-5V DC - all are linear in response to Full Scale