The Design Of Distributed Electromagnetic Spectrum Real-time Monitoring System

The rapid development of radio technology has led to an exponential increase in the number of frequency devices.In order to alleviate the conflict between limited spectrum resources and a large number of wireless services,scientific and effective spectrum monitoring is needed to detect spectrum holes and provide support for dynamic spectrum access.At present,the spectrum monitoring methods adopted by relevant departments are to use professional spectrum detection equipment for one-time mobile testing or fixed-point long-term testing.The input of this method is high and the timeliness of obtained spectrum data is poor.It cannot accurately characterize the spectrum usage in the current environment.This paper presents a distributed electromagnetic spectrum real-time monitoring system.In the monitoring area,multiple detection nodes are set up.Each node selects the portable embedded system as the main control module and the software radio module as the spectrum data acquisition module.The host computer realizes spectrum visualization by analyzing and processing the spectrum data of the detection nodes.The monitoring network uses a self-organizing network based on the blank TV frequency band for implementing communication between the detecting node and the upper computer.First,the master module of each node drives the software radio module to collect spectrum data,and stores the collected data in the local spectrum database.Then,each node separately performs data pre-processing,calculates spectrum occupancy,and transmits the occupancy result to the upper computer by means of multicast communication.When accessing the single detection node data,the C/S architecture is adopted,the main control module is used as the server,and the upper computer is used as the client,and the socket communication protocol is used to realize data transmission between the two.Finally,the upper computer comprehensively analyzes the multi-dimensional spectral data in the time domain,frequency domain and spatial domain,and draws waterfall map,real-time spectrum map and spectrum map to realize spectrum visualization.When the system analyzes a large amount of spectrum data,the distributed calculation method is adopted,which reduces the calculation pressure of the upper computer and improves the data processing rate.In order to improve the calculation accuracy,when calculating the spectrum occupancy,the forward difference algorithm is used to smooth the noise threshold curve.This paper tests the spectrum detection error,the throughput and stability of the communication network and the spectrum visualization effect.The test results show that the designed system can basically realize the real-time monitoring of the electromagnetic spectrum,visually display the use of the electromagnetic spectrum in the current environment.