Research On Wireless Transmission Technology Of Multiplex Signal

Along with the development of information technology,communication system transmission signal type more and more complex,in order to more accurate and faster transmission multiple parallel signal and multipath signal wireless transmission technology research has been more and more attention,compared with the traditional way of cable transmission,wireless transmission mode can not only reduce the complexity of the layout and cost,to improve communication rate under the condition of also can be applied to the complex work environment,such as nondestructive testing,remote monitoring,such as car navigation environment.The research of low cost and high quality multi-channel signal wireless transmission system has important engineering application value.This paper first summarizes the research background,significance and the research trend at home and abroad,then introduces the multi-channel wireless signal transmission system and the related theory system on the basis of the overall design scheme of system scheme design and implementation of the detailed introduction and analysis of main contains multiplex signals and list/string and conversion circuit design,the transmission circuit,receiving circuit design,chip driver design,and 2FSK orthogonal demodulation algorithm programming implementation;Finally,the whole hardware realization system is tested and analyzed.The circuit design of the hardware part of the system is mainly composed of the multi-channel signal and serial/serial conversion circuit module,transmitting circuit module and receiving circuit module.Among them,the multi-channel signal and serial conversion circuit module connects the multi-channel signal and frames to form a highspeed serial signal,which is used as the modulation signal of the transmitting circuit module.The core of the transmitting circuit is a phase-locked loop with 2FSK modulation function.By changing the frequency division ratio of the phase-locked loop,2FSK modulated signal with continuous phase can be output.The receiving circuit is mainly composed of a down-conversion circuit,a low-pass filter,a digital-to-analog converter,a controllable gain amplifier,an analog-to-digital converter,and an FPGA arithmetic processing circuit.The 2FSK baseband signal is demodulated from the modulated RF signal by using the 2FSK orthogonal demodulation algorithm,and the multichannel signal is restored through a series-parallel conversion circuit.System software part design,mainly composed of signal and strung together,string together and conversion program,2FSK/orthogonal demodulation algorithm and chip driver three parts,first introduced the signal and strung together,string together and conversion program/design train of thought,and gives the simulation results based on verilog language,then detailed introduces a 2FSK principle and implementation method of quadrature demodulation algorithm,finally,this paper introduces the design of each module chip driver,and the simulation results is presented.The results obtained through hardware testing: when the transmitting frequency of 2FSK modulation is 24.002 GHz,it represents the sending data "0";when the transmitting frequency is 23.998 GHz,it represents the sending data "1";moreover,the transmitting output power is greater than 3.25 dBm,and the phase noise at the 24 GHz point frequency is-81.55dBc/ hz@-10 khz.When the system transmits parallel data of 2 channels and the data code rate of each channel is 700 Kbps,the receiver can stably recover the multichannel signal.