PRN-FSK System Target Detection Signal Processing Technology

With the increasingly complex battlefield electromagnetic environment, the performance of radio detector has to meet strict demands. Under the circumstance of the presence of interference signal, target detection system can still get the speed and distance information of the target. Pseudo-Random Noise Code-Frequency-shift keying target detection system has the same spectrum characteristics of pseudo-random noise code spread and frequency hopping signal. What is more, it also adopts the related processing in fixing distance. So the system has strong anti-interference ability, which would be widely used in the radio fixed distance system.That is to say, this is a promising method of radio target system.PRN-FSK target detection system utilizes a pseudo random code to control the carrier frequency. The pseudo random code chooses different carrier signals to transmit. After mixing the transmission signal and the echo signal, we can extract the Doppler signal through a low-pass filter and measure the speed of the target through the Doppler signal. What is more, we can get the distance by utilizing the autocorrelation properties of the pseudo random code.Firstly, the principle of PRN-FSK target detection system was analyzed in this paper. Two different methods to extract the target speed and distance information were proposed in this paper. The complete simulation model was established to verify the correctness of the signal processing method. The two signal processing methods were compared and the best methods of signal processing were proposed. The solution is that extract the Doppler signal from the low-frequency signal and extract the division code signal from the intermediate frequency signal.Based on the success of theoretical simulation, the hardware circuit diagram has been designed and debugged. The power supply, the low-pass filter amplifier circuit, AGC circuit, voltage shaping circuit, ADC modules were included in the design.The verification of algorithm was completed on FPGA. The algorithm of the speed module in the frequency domain and fixing distance algorithm in time domain have been implemented. At last verify the validity of the hardware circuit board through the Chipscope.