| Since China’s department in charge of railway officially has determined to fully introduce GMS-R technology from Europe for network construction from 2000, up to the end of 2013, the China’s high-speed railway revenue kilometers have reached more than 10,000 km, owing to which China has become a country with most comprehensive high-speed railway system technology, strongest integration capability, highest operating speed, longest operating mileage and largest scale under construction in the world; therefore, the GSM-R network is widely applied. Along with continuous development of operators’ network(such as Telecom, UNICOM, China Mobile, etc.), increase of network density, low-cost equipment use(serious indicator degradation), and due to wide application of other wireless facilities and even illegal use, the electromagnetic environment around railway GSM-R network is getting more complicated increasingly, a trend of spreading from few hot spots to full line exists. Such situations have seriously interfered with the normal operation order of high-speed rail, jeopardized the driving safety, and even caused greater negative effect on the railway image. The railway bureau, which undertakes the maintenance task of high-speed rail operation, even more urgently needs for real-time monitoring and positioning of electromagnetic interference around GSM-R network, maintains a good electromagnetic environment of GSM-R network operations and carries out the real-time monitoring of the tower status, so as to maintain normal operation of railway wireless communication equipment and driving safety. Under such background, it’s necessary to research and develop a real-time GSM-R interference monitoring system.In the development of such system, this paper have mainly studied the online interference monitoring technology of GSM-R network, and conducted the experimental verification for such technology. As for study of network interference monitoring technology and timeliness, the long-time, uninterrupted, real-time and online continuous monitoring, network data collection, spectrum scanning and analysis are mainly conducted for signals in GSM-R uplink frequency 885MHz~889MHz, and downlink frequency of 930MHz~934MHz(total 8M bandwidth), including signals of the operators within such bandwidth(China Mobile, China Unicom, Telecom); all received signals are monitored and acquired(24h) in real-time and recorded and stored in the base station, the synchronous signal analysis is used to demodulate, separate and measure the interference signals and GSM-R signals, so as to obtain the signal strength, direction and angle; by use of characteristics of antenna, such as directivity, and multidimensional orientation, the synchronous positioning is conducted in two base stations to determine the location of interference source, in order to achieve early warning and alarm. In experimental verification, the interference test machine is used for simulation range interference, then the portable spectrometer is used for scanning and comparing the scanned results with the results scanned in real-time by such system to verify the conformity of overall amplitudes of effective signals and interference signals in the uplink and downlink spectrum segments collected in the center platform(software interface) with those measured by the spectrometer, so as to eventually determine whether the system can measure the spectrum on site in real-time.Through study of above GSM-R online interference monitoring technology and on-site experimental verification, it has been verified that the system under support of such technology can work stably and reliably, monitor the interference signals in GSM-R frequency band in real-time, realize the remote supervision and judgment of electromagnetic environment; and the GSM-R base station does not need to be shut down during interference investigation by such system, which does not cause influence on normal operation and safety of the railway, overcomes the problems of inefficiency and low accuracy of manual acquisition by waiting on the site, promotes the regular maintenance working efficiency of grass-roots unit, and creates better safety and economic benefits, thereby having good popularization application prospects. |
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