NVIS fast frequency selection system and method based on passive monitoring

Abstract

The invention provides an NVIS fast frequency selection system and method based on passive monitoring. The system comprises an NVIS antenna, a duplexer, a communication device and a real-time frequency spectrum monitoring module, the real-time frequency spectrum monitoring module and the communication device share the NVIS antenna through the duplexer, when the communication device is idle, the real-time frequency spectrum monitoring module receives a radio frequency signal through the NVIS antenna and analyzes the frequency spectrum characteristics of the radio frequency signal, and when the communication device is busy, the duplexer switches the NVIS antenna to a communication device connection state, thereby realizing the integration of frequency selection and the communication device. According to the NVIS fast frequency selection system provided by the invention, on the premise of sending no radio detection signal, the system receives an external ionospheric reflection signal to track the change trend of ionized layer F2 layer critical frequency f0F2, quickly captures ''frequency spectrum holes'' in a communication gap, adjusts the communication frequency in real time, and has the advantages of high frequency selection precision, high speed, high concealment, etc.

Description

technical field [0001] The invention relates to the technical field of short-wave communication, in particular to an NVIS fast frequency selection system based on passive monitoring and a method thereof. Background technique [0002] Sky wave and ground wave are two basic propagation paths of high frequency communication. Under theoretical conditions, the ground wave propagation distance usually does not exceed 80km (in practical applications, this distance will be shorter due to terrain constraints, or even only a few kilometers), while the sky wave propagation distance is usually not less than 200km. Therefore, the area about 80-200km away from the launch point cannot be covered by short-wave radio waves, which is called a "blind area" (quiet area), such as figure 1 shown. [0003] NVIS (Near-Vertical Incidence Sky-wave, near-vertical incident sky-wave) is a propagation mode using high-elevation antennas, such as figure 2 As shown, by adopting a launch elevation angle ...

AI Technical Summary

Problems solved by technology

However, such spectrum monitoring equipment is usually complex and bulky, and is separated from frequency-using equipment. Mobile stations (especially backpack stations) cannot obtain monitoring station data in real time, so it is difficult to meet actual work needs.

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