Method for estimating cycle slope and starting frequency of hyperbolic frequency modulated signals

Abstract

The invention discloses a method for estimating the cycle slope and the starting frequency of hyperbolic frequency modulated signals. The method comprises the following steps of first, acquiring a data sequence, second, initializing parameters, third, calculating the power spectrum of data in the ith short time window, fourth, estimating the instantaneous frequency fi of the data in the ith short time window by using a maximum gammagraphy method, fifth, estimating the zero crossing point interval gi = 1 / fi of the data in the ith short time window, sixth, judging whether the data of all the short time windows are processed, executing the third step if not processed, otherwise executing the seventh step, seventh, sliding median filtering is conducted on a zero crossing point interval estimating sequence {gi, i = 1, 2, ..., I}, eighth, calculating the kth time interation weight, ninth, judging whether an interation stopping condition is met or not, if not, executing the eighth step again, otherwise executing the tenth step, and tenth, calculating the cycle slope and the starting frequency. According to the method, complex calculating and parametric search are of no need, the stability is strong, and quick and high-precision estimation of the parameters can be achieved.

Description

technical field [0001] The invention belongs to the field of signal processing, and in particular relates to a method for estimating the period slope and initial frequency of a hyperbolic FM signal. Background technique [0002] The hyperbolic FM signal has Doppler invariance, which makes it especially suitable for detecting high-speed small targets, which makes the hyperbolic FM signal widely used in the fields of underwater acoustics and radar. The cycle slope and the initial frequency are two basic parameters that characterize the frequency characteristics of the linear hyperbolic FM signal. If these two parameters can be estimated, the obtained hyperbolic FM signal can be recovered under the condition of known signal pulse width , which is of great significance to underwater acoustic countermeasures and radar countermeasures, so its estimation problem is an important research content in the field of underwater acoustic and radar signal processing. [0003] At present, t...

AI Technical Summary

Problems solved by technology

Both the maximum likelihood method and the nonlinear least squares method need to solve nonlinear equations, but for hyperbolic FM signals, the nonlinear equations that these two methods need to solve do not have analytical solutions, so numerical solutions need to be used, which is Increased the difficulty of solving and the complexity of calculation

The method of combining time-frequency analysis and image processing requires repeated use of time-frequency filters in order to achieve better estimation results, which greatly increases the calculation amount of the algorithm and limits its engineering practicability

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