Linear frequency modulation continuous wave radar distance measuring method

Abstract

The invention provides a linear frequency modulation continuous wave radar distance measuring method. According to the method, a discrete Fourier frequency spectrum curve of an intermediate frequency signal is fitted through interpolation to find out a frequency value corresponding to a spectral line number with th maximum value on the frequency spectrum; the frequency value is much closer to the theoretical frequency value. Accordingly, the method is capable of reducing error caused by picket fence effect and greatly improving precision of FMCW (Frequency Modulated Continuous Wave) distance measurement. In addition, the method is capable of mainly concentrating white noise frequency spectrum curves, which are distributed evenly, in a high frequency band through discrete Fourier transform; the frequency of middle-band signal is in a low-frequency band; a frequency spectrum of a high-frequency band has less influence on the frequency spectrum of the low-frequency band, so that the method does not have great influence on calculation precision under a certain noise influence, thus ensuring the reliability of the calculation result.

Description

technical field [0001] The invention relates to the technical field of radar ranging, in particular to a linear frequency modulation continuous wave radar ranging method. Background technique [0002] Radar ranging is a non-contact measurement, so it will not cause damage to the target object, and can be used in many special environments to achieve high-precision measurement. The principle is: send a linearly transformed frequency-modulated continuous wave to the target, return the electromagnetic wave after reaching the target, receive its echo, mix the echo with the local oscillator signal to obtain an intermediate frequency signal, and the distance information is included in this intermediate frequency signal. Signal processing can extract the distance information. [0003] LFM continuous wave radar has many advantages that other radars do not have: no distance blind zone, high distance resolution and low radiation power. Due to the high accuracy required for liquid lev...

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Problems solved by technology

[0004] In the process of realizing the present invention, the applicant found that the existing linear frequency modulation continuous wave radar ranging method has the following defects: due to the need for discrete Fourier transform for ZFFT, CZT and zero-padding spectrum refinement, non-integer values ​​are calculated by interpolation However, the difference between the spectral line amplitudes near the maximum value is small, and due to the influence of spectrum leakage and noise on the spectrum, it is easy to misjudge the maximum value and affect the accuracy of the distance.

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