Modulation Signal Spectrum Analysis And Calculation Of Occupancy

Radio frequency spectrum is an important national strategic resource.Like land and mineral resources,it is non-renewable.Due to the increasing demand for spectrum from various rapidly developing communications services,the problem of lack of spectrum resources becomes more and more obvious.Radio monitoring is the key to ensuring the stable operation of various wireless services.Radio spectrum detection is an important part of radio spectrum management.Radio monitoring stations can perform tasks such as frequency measurement,signal amplitude and energy distribution,radio positioning,bandwidth measurement,and dynamic spectrum occupancy monitoring.These are inseparable from the spectrum analysis of the signal.It can clearly be seen that spectrum analysis plays an important role in radio monitoring.This paper first analyzes the spectrum of the modulated signal,simulating a carrier frequency estimation method based on the power spectrum,and estimating the carrier frequency and bandwidth of the signal and obtain the range of frequency distribution.Then,Simulation of AM analog modulation,binary and M-ary digital modulation,and signal information obtained from spectrum analysis.Besides,design of a GUI interface to implement multiple digital modulation methods,using power spectrum method to estimate the carrier frequency of various modulation signals,and analysing the simulation performance of the carrier estimation.The performance shows that the accuracy of the carrier frequency estimation is related to the SNR,and the M-ary modulation is more susceptible to the SNR.In addition,experiments on spectrum occupancy calculation are carried out in this paper.Firstly,the methods for solving noise thresholds are analyzed experimentally using offline FM broadcast monitoring data.The results show that the difference comparison method is effective for calculating the noise threshold,and the calculated noise threshold is more accurate.Next,using the data monitored by the spectrum sensor node developed by the laboratory to analyze the occupancy,processes the 24-hour spectrum monitoring data,and analysis the spectrum of several service frequency bands of 20M-3GHz.In order to facilitate the analysis of data,spectrum occupancy images of several service frequency bands are plotted.From the calculation results,we can see that in the monitoring site,the overall occupancy of the FM broadcasting band is not high,and the occupancy situation is relatively decentralized,but several occupied channels are relatively fixed.The spectrum occupancy of the UHF broadcasting TV band is mainly distributed in the 470-In the 560 MHz band.For the GSM 900 service band,uplink and downlink monitoring data differ greatly,but the uplink frequency band is not unoccupied.This is because of the uplink frequency band,the base station always sends the data to the user,but the user sends the uplink to the base station.The signal is sent randomly.Through Django's Web framework,a front-end interface was designed to achieve the visualization of data by reading local data files at regular intervals.