There is inevitable unbalance in the dual-rotor system of the aero-engine, the beat vibration will occur to engine when two rotors are operating at approximately the same speed.

Trent reverse reflection device is adopted to offset the effect caused by beat and cross sliding during displacement or vibration and to enhance measurement sensitivity and accuracy nearly one time.

The horizontal decanter centrifuge is a dual rotor system with small rotating speed difference, of which unbalanced vibration is a "beat" signal.