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. The carrier synchronization system comprises a frequency converter used for performing down-conversion on a received input signal and outputting the input signal to a multiplier; a numerically controlled oscillator used for generating carriers and outputting the sameto the multiplier; the multiplier used for mixing the received signal to obtain a mixing signal and outputting the mixing signal; a first frequency locking loop and a second frequency locking loop used for performing frequency discrimination on the frequency of the mixing signal to output frequency discrimination signals; a phase locked loop used for performing phase discrimination on the phase ofthe mixing signal to output a phase discrimination signal; and a tracking loop used for judging frequency discrimination signals output by the first frequency locking loop and the second frequency locking loop and the phase discrimination signal output by the phase locked loop, switching the connection relation of the three loops with the tracking loop according to the judgment result and controlling the frequency of the carriers output to the numerically controlled oscillator. The system provided by the invention can achieve large range 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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