Simulation And Design Of Pseudo - Random BPSK RF Circuit

Pseudo random BPSK modulation technology uses m-sequence to make carrier frequency have 0/Ï€ phase modulation, reducing the transmission signal units with energy, making the enemy hard to detect, reducing the chance of a captured. When modulated carrier signal detect a target, it will have echo signal reflected, mixing with emission signal, the frequency of intermediate frequency signal through the low-pass filter, the signal is delayed pseudo-code signal and the product of the doppler signal; This signal associated with the local pseudo-code signal as processing, if appear peak, then related, realizing the distance function; After detection to extract the doppler signal, the speed of the target can be calculated, we can realize the function of speed.This paper first analyzes some basic theory of the pseudo random BPSK modulation, on the basis of that the pseudo random BPSK RFsystem has carried on the theoretical research and analysis, the structure diagram of the system are given, this paper expounds the working principle, and based on ADS simulation software simulation, analysis was carried out on the radio frequency system, analyze the RF circuit modules and design parameters is given.In this article, using the element width 100ns pseudo-code signal to control the microwave switch, make the signal transmission in the two different length of transmission line, distance difference decided the phase difference, so it can realize the modulation of the signal phase 0/Ï€. Based on ADS software to design the circuit structure of each module, and do the simulation, by analyzing the simulation results, modify the design circuit and make the comply with the design index of each RF module; In the process of the simulation, if the result is not very ideal, analyze and find out why,modification measures are put forward, such as when designing circulator by modifying the circuit, makes the circulator design into a round shape.Then based on the Altium Designer software drawing PCB map of RF circuit, after the completion of the system board welding and debugging for the RF module; In the process of debugging, the RF oscillator, the microwave switch are the important debugging, and debugging the result conforms to the anticipated target, to ensure that the circuit can meet the design requirements. Finally, the results of debugging is analyzed, and improvement measures are put forward.