Design And Implementation Of Multi-mode And Multi-symbol Rate Adaptive Transmitter System

With the rapid development of communications,especially satellite communications,data transmission rates are getting higher and higher,and general transmitters are no longer able to meet design requirements.In order to solve this problem,the industry has proposed an adaptive communication method.Because adaptive communication requires good anti-interference,it is of great significance to study its evasion interference.In the avoidance of interference,a variety of modulation methods and a variety of symbol rates are adopted,and the system adaptively transforms according to different requirements to solve this problem.In adaptive communication,the transmitting end needs to detect the occupancy of the channel to select the manner in which the data is transmitted.If the channel is idle,it can be designed with full bandwidth.If the available bandwidth of the channel is small,a narrowband design is employed.This paper studies adaptive transmitters in the field of communications.Firstly,the research background and significance are introduced,and the implementation of adaptive transmitter is proposed.Then the existing multi-rate and spectrum sensing technologies are introduced,and the advantages and disadvantages of adaptive transmitters are compared and analyzed.When communicating,the transmitter can select the symbol rate and modulation mode of the transmitted data based on the perceived different available bandwidth.The optional symbol rates are 250 Msps,31.25 Msps and 3.90625 Msps.The modulation methods are BPSK,QPSK and 8PSK.The transmission signal is subjected to constellation mapping and shaping filtering,and is transmitted to the target sampling rate by up-conversion and interpolation filtering,and then transmitted through the DA end.In this paper,there are five channels of 0,31.25 MHz,-31.25 MHz,62.5MHz and-62.5MHz for channel switching.The transmitted signal has a sampling rate of 2Gsps and a center frequency of 1.5GHz.In hardware implementation,FPGA is used to implement the system architecture to implement multi-mode,multi-symbol rate adaptive transmitter system.This topic is based on Xilinx's Virtex-7 series of chips,using Verilog HDL hardware description language to achieve programming.The development platform used is ISE 14.7,which is combined with Modelsim and MATLAB for simulation verification.