Modulator And Demodulator Design Of Telemetry System Based On Software Radio

Telemetry technology is a distance-measurement technology for parameters of the objectto be measured; it is widely used in industry, agriculture, science and national defenseconstruction. In this paper, a system which can fulfill the modulation and demodulation ofFSK, BPSK and QPSK based on the principles of software radio and FPGA is designed tosolve the problems of low spectrum utilization and single modulation mode of the radiotelemetry system and to meet the requirements of baseband multi-mode modulation. Thissystem is conducive to the telemetry system standardization, modularity and rapid design.On the basis of analyzing the relevant domestic and overseas technologies, this paperpresents a program of telemetry modulation and demodulation system based on software radio,and provides the system parameters, technical specifications and system designimplementation. Moreover, this paper also designs a transmitting system using DDS based onFPGA to generate FSK, BPSK and QPSK modulation, and a receiving system usingquadrature demodulation model to complete the demodulation of three modulated signal.The system employs a top-down designing method that the down-level design usesVHDL hardware description language and the top-level design uses schematic diagrams. Thispaper designs the system with encryption and decryption modules, DDS module andmodulator and demodulator and tests the functions of the whole system.Finally, based on the hardware platform of FPGA as the core, system transmission rate,the carrier frequency, bit error rate and other performance indicators are tested and the testresults are provided. Then the problems in the design and debugging are analyzed. Theexperimental results show that not only the bit error rate of system is low, the indicators meetthe expected requirements, but also the system has good stability and flexibility.