Optical-electronic integrated rf leakage interference cancellation system and method for cw radar

An optical-electronic integrated radio frequency (RF) leakage interference cancellation system for the continuous wave (CW) radar, wherein comprising a microwave photonic link, a cable link, an electronic coupler and a feedback control unit;

• the microwave photonic link comprises an electro-optic modulation unit, an optically enabled microwave phase shift unit, an optically enabled microwave time delay unit, an optically enabled microwave amplitude tuning unit, and a photo detection unit, which are connected in sequence by optical fibers or optical waveguides;
• the electro-optic modulation unit is constructed by a direct modulation laser, or by a laser and an electro-optic modulator;
• the electro-optic modulation unit has the function of modulating the reference signal tapped from the transmitter source of continuous wave on the lightwave generated form the laser;
• the electro-optic modulation unit outputs the optically carried microwave signal;
• the optically enabled microwave phase shift unit has the function of tuning the phase of the optically carried microwave signal from the electro-optic modulation unit, which ensures the out of phase relationship between the cancellation signal and the leakage interference signal at the input ports of the electronic coupler;
• the optically enabled microwave time delay unit has the function of tuning the delay time of optically carried microwave signal from the optically enabled microwave phase shift unit;
• the optically enabled microwave amplitude tuning unit has the function of adjusting the amplitude of the optically carried microwave signal from the optically enabled microwave time delay unit;
• the photo detection unit has the function of the optical-to-electronic conversion for the optically carried microwave signal from the optically enabled microwave amplitude tuning unit and the generation of the cancellation signal;
• the cable link connects an electronic circulator and the electronic coupler;
• the electronic coupler has two input ports and two output ports;
• the two input ports are connected with the microwave photonic link and the cable link, respectively;
• for the two output ports, the one port outputs the residual leakage signal after the cancellation between the microwave photonic link and the cable link, which is input to the feedback control unit;
• the other port outputs the target signal after the cancellation between the microwave photonic link and the cable link;
• the feedback control unit monitors the residual leakage signal from the electronic coupler and then generates the control signal of the phase adjustment, the time delay adjustment and the amplitude adjustment to the optically enabled microwave phase shift unit, the optically enabled microwave time delay unit and the optically enabled microwave amplitude tuning unit respectively, which composes the feedback control loop.