Frequency Offset Estimation Method for HF Communication Based on Maximum Likelihood

Abstract

The invention discloses a method for estimating the frequency offset of short-wave communication based on maximum likelihood. The specific steps of the method are: the transmitting end transmits the data to be transmitted by the user, and the data to be transmitted by the user and the synchronous sequence of the front end form a data frame structure; the data frame structure Through digital up-conversion processing, the transmitted data sequence is obtained; the transmitted data sequence is transmitted through the short-wave channel and synchronously sampled, and the received data sequence is obtained at the receiving end; the frequency offset of the received data sequence is estimated by using the maximum likelihood criterion, and the frequency of the received data sequence is obtained. partial estimate. The invention solves the problems of signal phase rotation caused by large errors, uncorrectable errors, and sharp deterioration of system performance; while improving estimation accuracy, channel estimation is not required, which greatly reduces computational complexity; The frequent change of the crystal frequency of the receiver does not need to increase the equipment cost.

Description

technical field [0001] The invention belongs to the technical field of short-wave communication, and in particular relates to a method for estimating frequency offset of short-wave communication based on maximum likelihood. Background technique [0002] Short-wave communication refers to a radio communication technology with a wavelength between 100 meters and 10 meters and a frequency range of 3MHz-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, shortwave communication, an ancient and traditional communication method, is still widely valued by the 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 , Shortwave is the only mea...

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Problems solved by technology

[0005] In order to solve the above-mentioned problems, the purpose of the present invention is to propose a method for estimating the frequency offset of short-wave communication based on maximum likelihood, which solves the problems such as the rotation of the signal phase caused by large errors, the generation of uncorrectable errors, and the sharp deterioration of system performance; While improving the estimation accuracy, there is no need for channel estimation, which greatly reduces the computational complexity; at the same time, it avoids frequent changes to the crystal oscillator frequency of the receiver, and does not need to increase equipment costs

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