Carrier synchronization system suitable for relay communication platform of unmanned aerial vehicle

Abstract

The invention discloses a carrier synchronization system suitable for a relay communication platform of an unmanned aerial vehicle, comprising: a frequency converter for down-converting a received input signal and then outputting it to a multiplier; a numerically controlled oscillator for generating a carrier and outputting it to a multiplier The multiplier is used to mix the received signal to obtain the mixed frequency signal and output it; the first frequency-locked loop and the second frequency-locked loop are used to discriminate the frequency of the mixed frequency signal and output the frequency discrimination signal; the phase-locked loop It is used to perform phase detection and output phase detection signal on the phase of the mixed frequency signal; the tracking loop is used to judge the frequency detection signal output by the first frequency-locked loop and the second frequency-locked loop and the output of the phase-locked loop according to the preset threshold voltage The phase detection signal switches the connection relationship between the above three loops and itself according to the judgment result, and controls the carrier frequency output to the numerically controlled oscillator. The system provided by the invention can realize large-scale and high-precision carrier synchronization.

Description

technical field [0001] The invention relates to the field of communication technology, in particular to a carrier synchronization system suitable for a drone relay communication platform. Background technique [0002] Information transmission has become an essential part of social life today. However, when there is a war or natural disaster, the damage of communication equipment will cause the appearance of information islands. The UAV-based wireless communication forwarding platform is widely used due to its advantages of flexibility and low cost. However, since the UAV system is a dynamic system, the receiver has a large Doppler frequency shift. In this case, the carrier synchronization system must have a large capture range. At the same time, the wireless communication system requires better communication quality and better carrier synchronization precision. However, a single frequency discrimination system, a phase discrimination system or a traditional combination sy...

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Problems solved by technology

[0004] However, in the existing solutions, although the second-order phase-locked Costas loop has high precision, the capture range is relatively small, and it is difficult to cope with the large-scale frequency deviation of the UAV communication system in a sudden and harsh environment; the second-order The structure system of the combination of cross-product frequency-locked loop and third-order phase-locked loop is simple and high-precision, but due to the relatively small capture frequency range, it is difficult to cope with the Doppler translation introduced under extreme conditions such as high-speed flight or strong wind; use the empirical look-up table The characteristics of the feedback adjustment loop filter can adaptively change the bandwidth and synchronize accurately at any time, but the carrier synchronization algorithm he proposed is based on UAV and satellite communication, and the relative speed between the two is large, so the Doppler effect The system is relatively complex

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