Research On U/V Radio Signal Spectrum Monitoring System Based On USRP

"Radio spectrum is a limited natural resource and they must be used rationally,efficiently and economically," according to the radio rules published by the ITU.Due to the rapid development of radio communication technology,the contradiction between the supply and demand of U/V frequency band is increasingly prominent.In order to improve the utilization efficiency of radio spectrum resources scientifically,it is necessary to use advanced monitoring system to maintain the order of electromagnetic environment,so that the limited spectrum resources can be used reasonably and the radio communication can be guaranteed smoothly.This paper mainly studies the sampling theory and orthogonal transformation in software radio,and designs the overall framework of the monitoring system according to the specific requirements of radio spectrum monitoring.The main function modules of the system include:radio signal acquisition module,spectrum diagram and waterfall diagram display module,trigger and alarm module,data storage module,voice monitoring module,remote operation module.This article mainly carries on the modular design to the software platform.Among them,the radio signal acquisition module realized the control of USRP's built-in FPGA through programming,realized the setting of hardware platform parameters,and continuously acquired base band data through the cyclic structure to realize the acquisition of radio signals.The display module of spectrum diagram and waterfall diagram uses FFT power spectrum and PSD sub-vi to perform fast Fourier transform on the orthogonal data in time domain,obtain the spectrum information of the signal,and draw and display it through thewaveform.The data storage module adopts the producer and consumer mode to store the collected data synchronously through file operation.The trigger and alarm module USES the basic level trigger detection sub vi to trigger and alarm the signal data in the waveform whose amplitude is larger than the set threshold,and determines the frequency of the abnormal signal in real time.The speech monitoring module obtains the time domain waveform of the modulated signal through orthogonal demodulation and can play the audio signal by driving the sound card.The remote operation module publishes the software platform to the browser through the Web publishing tool,and realizes the remote operation and control of the system through the Web.This system can realize the monitoring of 50MHz~2.2GHz radio signals,and the maximum real-time processing bandwidth is up to 20 MHz.Finally,the spectrum monitoring system is tested and verified.After testing,all functional modules of the system can work normally.The frequency monitoring error of abnormal detection signals is relatively low,and the system can run stably for a long time.