Recovery method of coherent carrier wave and timing of burst mode GMSK

Abstract

The invention discloses a recovery method of a coherent carrier wave and timing of burst mode GMSK. The recovery method comprises alternatively performing forward operation and reverse operation on same GMSK signals in a square loop feedback loop of a receiving machine. The square loop feedback loop comprises a phase error detection module, a loop filter and a numerically controlled oscillator which are successively connected; an output of the numerically controlled oscillator is further connected with the phase error detection module; and the forward operation is operation performed on a GMSK signal flow arranged according to a receiving time sequence, and the reverse operation is operation performed on the GMSK signal flow arranged according to a receiving time inverted sequence. A real value is gradually approached through the forward operation and the reverse operation, which are alternatively performed on limited-length burst packet data, in the method, and then estimation precision of a frequency of a carrier wave and estimation precision of a phase of the carrier wave are improved. The method is used in an AIS receiving machine, can improve recovery performance of a carrier wave and timing of a signal, can improve receiving performance and can simplify structure of the receiving machine.

Description

technical field [0001] The invention belongs to the technical field of ship communication, and in particular relates to a coherent carrier and timing recovery method of burst mode GMSK (Gaussian filter minimum shift keying). Background technique [0002] With the development of the shipping industry, the trend of large-scale and high-speed ships is obvious, the number of ships and their load capacity continue to increase, and maritime traffic is becoming increasingly dense and busy. The ship-borne automatic identification system (AIS) is used to establish effective communication between the base station and the ship and between ships, thereby improving the safety and efficiency of navigation, while protecting the maritime trade environment. All AIS-equipped ships regularly send information, including ship identification, position, heading, speed, and other information, to achieve information interaction. The satellite-based AIS system (SAT-AIS) can improve coverage and secu...

AI Technical Summary

Problems solved by technology

Existing algorithms directly perform FFT transformation or estimation on the burst packet data. Due to the limited length of the burst packet, the phase and frequency estimation accuracy is limited, which is much lower than the carrier and timing recovery accuracy of continuous mode GMSK, so it is difficult to use coherent Demodulation method

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