Synchronization method based on PN sequence in NAVDAT (Navigational Data)

Abstract

The invention discloses a synchronization method based on a PN sequence in NAVDAT (Navigational Data). The method comprises following steps of (1), inserting the known PN sequences of a receiving end on the subcarriers of OFDM symbols as synchronization headers, at a NAVDAT sending end; (2), carrying out time synchronization by using a method correlated to local PN sequences, at a NAVDAT sending end; (3), using the ratios of current correlation values and intra-window correlation values as the measurement standards of correlation peaks; (4), finishing frequency synchronization through adoption of a same PN sequence frequency domain conjugate correlation method. According to the method, the time synchronization is carried out by using the PN sequences with synchronous frequencies fully, the time synchronization accuracy is improved, the ratios of the current correlation values and the average value of the intra-window correlation values are taken as the measurement standards of the correlation peaks, the influences of the amplitude of the actually received signals on the correlation peak values are eliminated, the frequency synchronization is finished by using the frequency domain conjugate correlation method, and the synchronization method provided by the invention has the advantages of simple realization, low calculation complexity and high synchronization accuracy.

Description

technical field [0001] The present invention relates to a synchronization head design and synchronization method for a wireless mobile digital communication system, in particular to using a PN sequence to simultaneously complete time synchronization and frequency synchronization with relatively low computational complexity when there is no integer frequency offset. A synchronization head design and synchronization method applied in NAVDAT (Navigational Data, navigation data) digital communication system. Background technique [0002] The NAVDAT digital communication system is a digital broadcasting system that works in the 500KHz frequency band and is used for maritime mobile services to ensure maritime safety and secure transmission of relevant information from the shore to the ship. This digital communication system provides broadcast transmission services for various types of messages and is encrypted. The messages broadcast include but are not limited to navigation safe...

AI Technical Summary

Problems solved by technology

When there is no frequency offset, the sub-carriers of the OFDM system are orthogonal to each other, there is no inter-carrier interference, and the system performance is good; when there is a frequency offset, the orthogonality between sub-carriers will be destroyed, causing inter-carrier interference. A small frequency offset results in a large performance loss

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