The Research On Communication Ranging And Time Synchronization

With the development of spread spectrum communication technology, timesynchronization requirements of modern warfare, communications ranging and timesynchronization technology based on the principle of spread spectrum communication havebeen widely used in military and civilian applications. More and more military equipmentand handheld terminal system requires high-precision time synchronization.Firstly, this paper study the principle of uncoherent ranging used in rangingsynchronization, made a detailed analysis of the use of the two terminals send each othermutual income, calculat the system clock difference and distance between devices, aswell as analysize the basic structure of the system model. Secondly, papers make a detaileddiscussion of the increasing of the bandwidth to improve the system to achieve theimmunity of spread spectrum communication based on the Shannon theorem. And papersmake researches on the pseudo-random sequence, including M sequence, Gold sequence,their generation process, and their characteristics, also shows a block diagram of the DSsystem, explores the working process of the system model.This paper make deep research on the specific algorithms-in time synchronizationtechnology, including code acquisition, code tracking and carrier tracking, is the keytechnologies of system functions. In the capture algorithm, this paper in turn compares theserial, parallel, and serial and parallel hybrid capture, and finally adopt the more advancedfast FFT capture technology. In the code tracking algorithm, papers particularly study thecode delay lock loop and a phase detector, the realization of the phase of thesynchronization code based on the principle of the delay lock loop, and in the carriertracking algorithm, this paper specifically study the frequency pulling, FLL frequencytracking and PLL phase tracking to achieve the tracking of the carrier frequency, the carrierphase alignment, and to eliminate the influence of the doppler shift of the system.In the system design, this paper use FPGA and DSP to made the system, FPGA isxilinx’s XC4VSX5, software is ISE12.3, logical language is veilog and VHDL, and DSPchips, along with the completion of PC software to capture and track the pseudo-codesignal. After commissioning of the system, with a short computation time, easy operationand high precision time synchronization. Ns can be achieved initial level timesynchronization.