Laser Doppler velocimeter with differential detection for anti-jamming

In order to suppress occasional jamming signal and to improve the use of the local oscillator power, a differential detection method is proposed in LDV scheme employing two photodetectors, where the main detector receives the Doppler signal while the auxiliary one detects outside jamming signals. The effectiveness of the method is verified through jamming signal rejection experiment. Theoretical analysis and simulation indicate that the SNR of the system is sacrificed to eliminate jamming signal. The differential detection decreases the SNR of the system since the noise yielding in two differential currents are mutually independent and cannot be eliminated. The jamming signal rejection experiment shows that the differential detection is capable to reduce nearly 90% of the amplitude of the occasional jamming signal, thus improving the measurement accuracy of the Doppler frequency and further improving the velocity measurement precision.