Synchronous head capturing method under extremely low signal-to-noise ratio of short-wave communication

Abstract

The invention belongs to the technical field of short-wave communication, and discloses a synchronous head capturing method under an extremely low signal-to-noise ratio of short-wave communication. The method comprises the following steps of: intercepting a receiving sequence by using any sampling point, and respectively carrying out isometric segmentation on the intercepted receiving sequence anda local sequence; carrying out correlation on each section of receiving sequence and a corresponding section of local sequence and carrying out FFT (Fast Fourier Transform) to determine the maximum amplitude value of the FFT sequence so as to obtain the maximum amplitude value of Q sections; summing the maximum amplitude values of the Q sections, and taking the summed value as the peak value of the intercepted receiving sequence; traversing each sampling point of the receiving sequence to obtain a peak value corresponding to each sampling point so as to obtain a peak value curve, and selecting the sampling point corresponding to the maximum peak value in the peak value curve as a synchronous starting point of the whole receiving sequence. According to the synchronous head capturing method, the synchronous point can be accurately found, the change condition of the frequency offset of the receiving section and the transmitting section can be mastered, and synchronous capturing can be achieved under the conditions of the extremely low signal-to-noise ratio and the large frequency offset.

Description

technical field [0001] The invention relates to the technical field of short-wave communication, in particular to a method for capturing a synchronous head under extremely low signal-to-noise ratio in short-wave communication. Background technique [0002] Shortwave communication refers to a radio communication technology with a wavelength of 10 meters to 100 meters and a frequency range of 3MHz to 30MHz. The radio waves emitted by short-wave communication must be reflected by the ionosphere to reach the receiving end. The communication distance is relatively long, and it is the main means of long-distance communication. Despite the continuous emergence of new radio communication systems, short-wave communication, an ancient and traditional communication method, is still widely valued by the whole world. Not only has it not been eliminated, but it is still developing rapidly. Because it has advantages that other communication systems do not have: First, short-wave is the on...

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Problems solved by technology

[0006]However, in the prior art, synchronous acquisition is mainly carried out under the condition that there is no frequency offset or fixed frequency offset between the transmitting and receiving parties, and it is rarely aimed at the harsh communication environment (extremely low signal-to-noise ratio) for simultaneous acquisition in the presence of varying frequency offset

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