Synchronous capturing method for short-wave multi-carrier signals

Abstract

The invention belongs to the technical field of communication, and particularly relates to a method for synchronously capturing a short-wave multi-carrier signal with a leader sequence. The method comprises the following steps of: performing power spectrum analysis on a signal in a time domain and a frequency domain simultaneously in a sliding window manner by utilizing leading audio frequency information in the signal, and covering frequency offset of a plurality of positive and negative subcarrier intervals on the frequency domain by a time-frequency sliding window which comprises a plurality of multi-carrier symbols on the time domain, taking the leading sound average signal-to-noise ratio of a plurality of symbols in the time-frequency sliding window as a capture judgment standard; if the average signal-to-noise ratio of the leading sound in the current sliding window length is greater than the capture threshold and the number of symbols with high signal-to-noise ratios is greater than a certain value, it is considered that the capture is successful; meanwhile, the time domain position and the frequency domain position corresponding to the current sliding window are respectively the calculation basis of the initial time offset estimation value and the initial frequency offset estimation value; according to the method, the characteristics of the leading sound signals are fully utilized, multi-symbol time-frequency analysis is combined, normal synchronous capture can still be performed under large frequency offset, and the robustness of synchronous capture is improved.

Description

technical field [0001] The invention belongs to the technical field of communication, and in particular relates to a method for synchronous acquisition of short-wave multi-carrier signals with preamble sequences. Background technique [0002] Shortwave communication is an important wireless communication method in the field of long-distance communication because of its simple equipment, flexible communication methods, strong invulnerability, and long communication distance. It is also widely used in military and civilian communications. A series of complex phenomena such as path delay, fading, Doppler frequency shift, frequency shift diffusion and radio interference, and because of the large multipath delay, for most short-wave communication systems, the short-wave sky-wave channel has frequency selectivity, resulting in short-wave Severe fading and symbol interference of communication signals; multi-carrier technology has outstanding advantages in overcoming multipath propa...

AI Technical Summary

Problems solved by technology

[0004] At present, there are mainly two methods for synchronous acquisition of short-wave multi-carrier signals with preamble sequences: 1) synchronous acquisition based on preamble sequences, the premise of this method is The receiving end knows the preamble sequence pattern design rules of the transmitting signal; generally, signal correlation detection is performed based on the periodicity of the preamble sequence, so as to realize the synchronous capture of the signal; 2) use the time domain sliding window to detect the power spectrum of the preamble sequence, Calculate the sum of the signal-to-noise ratios of each preamble, and set the capture threshold for signal capture; method 1 is suitable for cooperative communication, but in the non-cooperative situation, it cannot be used for semi-blind or full-blind states where the receiving end does not know the design rules of the sending end preamble. Use this method for synchronous acquisition; method 2 only uses the time-domain sliding detection window without considering the fact that the power of the leading tone will become relatively low when the received signal is at a large frequency deviation, so that the signal is prone to occur at a large frequency deviation Missed detection makes it impossible to capture synchronously; in addition, this method only roughly detects the starting position of the signal, and does not consider the estimation of the initial time offset and frequency offset; therefore, although these two methods can achieve signal capture in some cases, However, in the case of non-cooperative communication or large frequency offset, there will be limitations, resulting in inability to synchronize correctly

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