Linear frequency-modulated parameter estimating method and implementing device thereof

Abstract

The invention belongs to the technical field of digital signal processing and provides a linear frequency-modulated parameter estimating method with high precision, low complexity, high speed and high efficiency and an implementing device thereof. The invention adopts a technical scheme that: by means of an energy barycentre interpolation estimation and Radon ambiguity transformation (RAT) based modulating frequency estimating method, the method mainly comprises the following steps of: for a given input signal s(n), calculating an ambiguity function AFs(tau, xi) of the input signal s(n); exchanging scanning straight lines xi=k tau continuously; figuring out the projection of AFs(tau, xi) on the scanning straight lines by means of Radon transformation; recording all projection values; constructing a panorama discrete spectrum; searching out the peak position of the panorama discrete spectrum; estimating the projection value of the actual peak value; obtaining the estimated value of thesignal modulating frequency; searching out the peak value spectrum of a fractional order Fourier spectrum; and figuring out the energy barycentre position of the spectrum so as to estimate the signalbarycentre frequency. The method is mainly applied to the linear modulating frequency signal parameter estimation in the digital signal processing.

Description

technical field The invention belongs to the technical field of digital signal processing. In particular, it relates to a method for estimating two most basic parameters of a chirp signal with high precision—modulation frequency and center frequency, that is, a chirp signal parameter estimation method and an implementation device thereof. Background technique A linear frequency modulation (LFM) signal is a non-stationary signal with special significance. As a spread spectrum signal with large time-bandwidth product, LFM signal is widely used in various information systems. In detection systems such as radar and sonar, the Doppler frequency of the target is approximately proportional to the speed of the target. When the target is moving at constant acceleration, the echo is a chirp signal. Echoes from maneuvering targets can also be approximated with LFM signals for a short period of time. In communication systems, chirp frequency modulation can be used as a means to reali...

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Problems solved by technology

However, in practical applications, only discrete FRFT spectra of finite samples can be obtained, which inevitably leads to energy leakage due to time-domain truncation, which makes the peak value of the spectrum smaller and the resolution lower.

In addition, discrete spectrum analysis will inevitably be affected by the fence effect, which will cause the position of the peak spectral line to deviate from the real position. If the spectral peak position is estimated directly by the method of discrete spectral peak scanning, the maximum estimation error may reach 50% of the spectral line interval

In applications where the accuracy of LFM signal parameters is relatively high, it is only possible to refine the scan step size and increase the sampling rate of the signal, but this will increase the amount of calculation in series, which is not conducive to engineering realization

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