With the rapid development of China's radio industry, the wide application of new radio technologies and new services, the number of radio stations (stations) has increased sharply, and the phenomenon of radio interference has also become increasingly serious.
Five types of interference
Radio interference refers to the phenomenon that electromagnetic energy enters the receiving system or channel through direct coupling or indirect coupling, resulting in the degradation of useful received signal quality, error or loss of information, and even blocking communication. Radio interference is generally divided into co-channel interference, adjacent channel interference, out-of-band interference, intermodulation interference and blocking interference.
Co-channel interference: The frequency of the unwanted signal is the same as the frequency of the useful signal, and the interference caused to the receiver receiving the co-channel useful signal is called co-channel interference.
Adjacent channel interference: The interference caused by the interference channel (station) adjacent channel power falling into the passband of the receiving adjacent channel receiver is called adjacent channel interference.
Out-of-band interference: The interference caused by the harmonics or spurious radiation of the transmitter in the passband of the received useful signal is called out-of-band interference.
Intermodulation interference: Intermodulation interference is divided into transmitter intermodulation interference and receiver intermodulation interference.
Blocking interference: When receiving weak useful signals, it is interfered by strong interference signals in the high-frequency loops on both sides of the receiving frequency, which is called blocking interference. If the receiver sensitivity is lowered, the communication will be interrupted.
Serious harm
The interference of radio interference to safety services such as aviation communications and maritime communications directly threatens social stability, national security and the safety of people's lives and property.
Interference with government departments and the military's communications system, such as the incident that interfered with the communications in Zhongnanhai, the military airport's interference with high-power cordless telephones, etc., seriously affected and disrupted the normal work order of the government and the military. War preparation and training have caused great harm to social stability.
Interference to aeronautical navigation communications and maritime communications, such as interference to the command frequency of a domestic airport tower, caused the aircraft to return to the flight, causing a serious backlog of flights; a certain airport's wireless navigation remote control station was interfered, which affected the safety of flights.
There has also been frequent interference with the Yangtze River radio station on the river. The interference with flood control, fire prevention, meteorology and other systems not only severely affected the command and dispatch during flood seasons and fire hazards, but also caused great losses to people's lives and property. Interference with the railway, transportation, power, telecommunications, radio and television and other industry systems has caused the failure of railway train scheduling, the temporary closure of highways, the delay of power repairs, the interruption of telecommunications services and the impact of people watching TV, listening to radio, etc. .
Monitor and locate interference sources
On the morning of September 6, the Shangqiu Radio Management Bureau removed a privately installed illegal satellite TV jammer in Jiangkou Township, Yongcheng City. After receiving the report, the Shangqiu Radio Management Bureau immediately arranged the relevant technicians of the monitoring station to drive to Jiangkou Township in a mobile monitoring vehicle. The monitoring personnel used a spectrum analyzer to monitor the interference signal and found that there was a strong broadband pulse signal in the 3.7-4.2GHz frequency band. Later, the direction of the interference signal was measured, and the direction was found to be near the township government. Through multiple direction finding and positioning, an illegal satellite TV jammer was quickly found on the top of a communication base station near the township government. The staff removed the illegal satellite TV jammer installed on the top of the communication base station according to law.
Radio monitoring can locate and locate various sources of radio interference, identify and find illegal or unauthorized radio stations, eliminate sources of interference, and ensure normal communication order.
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