A Low Complexity Synchronization Method for Satellite AIS Ship Positioning System
A positioning system, low-complexity technology, applied in satellite radio beacon positioning system, synchronization device, transmission system, etc., can solve the problems of AIS signal time slot conflict, processing inefficiency, estimation accuracy impact, etc., to achieve extended frequency offset Estimating range, solving synchronization problems, low-complexity effects
Active Publication Date: 2018-11-16
SHANGHAI JIAOTONG UNIV
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Problems solved by technology
This algorithm has a large estimation range and good estimation accuracy, but the estimation accuracy of its frequency deviation is affected by the search step size, and because the algorithm requires a large number of FFT / IFFT operations, its hardware implementation complexity is very high, processing very inefficient
[0006] Secondly, due to the large coverage area of the satellite antenna, time slot conflicts will occur when the AIS signals in the coverage area are received, and aliasing and interference will occur to the AIS signals of ships, which will easily lead to the failure of signal synchronization and demodulation
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[0051] Embodiments of the present invention will be described in detail below in conjunction with accompanying drawings and simulation examples: the present embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures have been provided, but the protection scope of the present invention is not limited Examples described below.
[0052] Such as figure 1 Shown is the overall block diagram of the system, the demodulation of multi-channel signals is realized based on the way of serial iterative interference elimination, and the present invention realizes figure 1 Modules involved in synchronization in the block diagram.
[0053] The satellite receives the AIS data signal sent by the ship, and the signal contains the interference of at least two aliasing signals. Taking this as an example, the synchronization method of the satellite AIS system includes the following steps:
[005...
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The invention relates to a low complexity synchronization method of a satellite AIS ship positioning system. The method comprises the following steps that a first step, a satellite receives an AIS data packet sent by a ship; a second step, a packet detection module carries out rapid packet-header-position rough search; a third step, according to a packet header position, an effective signal is intercepted and optimum sampling point search is performed, and the effective signal is input into a frequency offset estimation module; a fourth step, a frequency offset estimation scope expansion module is added into the frequency offset estimation module; a fifth step, the frequency offset estimation module uses a GMSK signal phase property to realize frequency offset estimation; a sixth step, a signal after frequency deviation compensation is input into a time synchronization module so as to carry out time delay estimation; a seventh step, a synchronization result obtained from the fifth step and the sixth step is used to demodulate the signal, a demodulation result is used to carry out serial interference cancellation, the third step is returned to and weak signal synchronization is performed. Compared to the prior art, the method of the invention possesses the following advantages that synchronization of the low complexity and high precision of a system demand is realized and so on.
Description
technical field [0001] The invention relates to the technical field of wireless communication, in particular to a low-complexity synchronization method for a satellite AIS ship positioning system. Background technique [0002] The AIS (Automatic Identification System) system is of great significance to modern navigation. The emergence of AIS makes navigation safer and maritime disasters are easier to monitor. With the advancement of AIS technology, satellite AIS technology has gradually become a research hotspot due to its remarkable advantages: larger coverage, higher quality service and fewer user restrictions. But the characteristics of the satellite AIS system itself also bring new problems to the realization of the system. [0003] First of all, the satellite AIS system needs to solve the problem of data packet synchronization. The scene of high-speed satellite movement will cause the Doppler frequency difference between the starships. In addition, considering the inf...
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IPC IPC(8): H04L7/00G01S19/46
Inventor 蓝威涛丁良辉杨峰钱良李悦
Owner SHANGHAI JIAOTONG UNIV