Research And Design On Enoding And Decoding Module Of RF Setting System

The RF setting technology is a technology which sends control commands to the flightobjective by wireless communication in the rear section of a flight, and goals to achieveprecise control of the flight status. Currently, RF setting systems are becoming miniaturized,low-power, and intelligent, but there is still a problem that the setting accuracy is susceptibleaffected by the noise and interference. To solve this problem, this paper will carry out aresearch and design on encoding and decoding module of the RF setting system, which willimprove the anti-interference ability of the system.On the basis of the research on the domestic and international status quo about settingtechnology and spread spectrum technology, and according to the anti-interference principleof error control coding technology and spread spectrum technology, this paper presents thegeneral planning of coding and decoding module of the RF setting system, which includeserror control coding sub-module, spread spectrum and despread spectrum sub-module, QPSKmodulation and demodulation sub-module. Meanwhile, the error control functions of （7,4）cyclic code and the anti-interference function of direct sequence spread spectrum wereanalyzed.Secondly, according to the general planning of the system, we design and simulate eachsub-module by FPGA. In the design process, coding the operating command into the （7,4）cyclic code can implement the function of finding and correcting an error bit; the design ofdual channel balanced Gold code generator can provide the duplex quadrature signals withdifferent PN code sequence, also will enhance the confidentiality of the system; based on thedesign of the sinusoidal signal generator in look-up table method, conducting QPSKmodulation in choice method, which has a simple structure and easy to realize. For experimental verification of the system, this paper finally design the circuit ofdownloading and configuration, the circuit of clock module, the circuit of power module, thecircuit of D/A and A/D converter, build hardware platform which is required for the systemexperiment, and conduct experiments for clock frequency, coding block, spread spectrumblock and QPSK block. The experimental results show that the error of each block are within2%and the error rate is2.29×10^-6,which meet the design requirements of the system.