Research On Digital Signal Processing Of TACAN Receiver

TACAN is an advanced system of aviation navigation.Its distance measurement relies on the traditional secondary radar ranging principle,and its azimuth measurement is completed by the special structure of the antenna on the ground and the pulse pair in a unique code.With the development of aerospace technology and increase need of more advanced navigation system,TACAN is a suitable subject because it has lots of chance for development in the digital level.In this paper,the algorithm research and improvement are carried out for TACAN receiver based on the digital signal processing.This paper focuses on the digital preprocessing filter after the sampling,peak extraction process,envelope extraction process and azimuth solution.The main content is the following five aspects:First,this paper puts forward using HackRF One to produce TACAN ground signal.Second,this paper adds a FIR filter to reduce the influence of adjacent channel interference on the TACAN system.Third,this paper proposes a peak extraction method using multiple dynamic thresholds to solve the interference of strong signal ringing.Fourth,this paper optimizes the Kalman filtering process based on the characteristics of the Kalman filter matrix in the envelope extraction of the TACAN system and reduces the amount of computation by using matrix symmetry.Fifth,this paper built a complete set of TACAN receiver experimental verification system by using a variety of software in combination with FPGA and software radio sets,and this system makes the whole test operation process of digital receiver complete by software.This system can simulate the ground signal of TACAN system in different cases,and also can upload the data processed by FPGA directly to PC,in which way the data can be easily processed and observed.Programs within the FPGA can also be easily adjusted on PC by using this system.The results of this paper show that the improved TACAN receiver still meet the precision requirement of TACAN system.After improvement,the peak information is extracted accurately,and the efficiency of computing for azimuth is also improved.