In recent years, with the rapid development in wireless communication, especially the rapid development in public mobile communications, the number of mobile base stations is increasing rapidly with the number of users growing.Base station antennas can be found everywhere in the city. In order to use the spectrum resource efficiently and maintenance the electronic wave in order, radio management organizations have built many radio monitoring net works in all area of city. During the "12th Five-year Plan" more radio monitoring stations will be built in Zhejiang Province to improve the distribution of the radio monitoring net work.According to the requirements of choosing location of monitoring stations released by National Radio Monitoring Center in1997, there should be no strong emission sources around VHF/UHF radio monitoring stations within500meters. In fact, it is so difficulty to find such kind of area in modern city with so many mobile base stations. Radio monitoring stations will be affected by the nearby mobile base stations, what is the regulation of the affect the distance between the two is changed, how much is the minimum protection distance?In this paper, After analysing the principle of superheterodyne, receiver, a series of experiments have been designed to simulate the working case of monitoring system next to the base station. How the parameters such as signal distortion and the accuracy of directing finding of a routine monitoring system changing when the distance between radio monitoring station and mobile base station changed have been studied.The results of this study can help radio management organizations when they are looking for the new proper site of radio monitoring station. Also this results can give the reasonable protect distance when new mobile base station will built near the monitoring station which is already there. When the radio monitoring station is close to the mobile base stations, the distortion signal found in the monitoring process may be caused by the strong signal emitted from the base station, so, appropriate technical means should be taken to reduce the impact of external strong signal on the monitoring results. |