Combined dual-beam and reference beam LDV for vehicle inertial navigation system

In order to adapt to the complicated environment of ground for the vehicle, a combined dual-beam and reference beam LDV is presented. It is made up of a single dual-beam subsystem and a single reference beam subsystem. Each optical head detects its own backscattering, and then the signal processing unit chooses one of the signals from the two detectors according to the validity of signal to extract the Doppler frequency and calculate the vehicle's velocity. Measurement results of combined LDV show good agreement with data obtained using DZL-1 electronic speedometer. The relative measurement error is less than 1.5%, which shows the reliability of the technique and potential for it to be applied to inertial navigation system.