Abstract
A time-domain ranging algorithm is proposed for a frequency-modulated continuous wave (FMCW) short-range radar sensor with high accuracy and low complexity. The proposed algorithm estimates the distance by calculating the ratio of the beat frequency signal to its derivative and thereby eliminates the restriction of frequency bandwidth on ranging accuracy. Meanwhile, we provide error analysis of the proposed algorithm under different distances, integral lengths, relative velocities, and signal-to-noise ratios (SNRs). Finally, we fabricate FMCW sensor prototype and construct a measurement system. Testing results demonstrate that the proposed time-domain algorithm could achieve range error within 0.8 m. Compared with the conventional fast Fourier transform (FFT) estimation scheme, the proposed method performs ranging without the requirement of complex multiplications, which makes it reasonable to be implemented in real-time and low-cost systems.
Highlights
Frequency-modulated continuous wave (FMCW) radars have been widely used for short range measurements benefiting from their high ranging resolution
The FMCW proximity radar sensor was extensively applied in industrial community, such as liquid level measurements [1], direction of arrival (DOA) estimation [2], radar altimeters [3,4], mechanical vibrations [5], and biomedical measurements [6]
To analyze the influence of the signal-to-noise ratio (SNR) on the range error, we conducted simulations for the time-domain ranging method based on derivative ratio with ∆F = 50 MHz, Tm = 10 μs, f c = 8.2 GHz, vr = 10 m/s, and N = 20
Summary
Frequency-modulated continuous wave (FMCW) radars have been widely used for short range measurements benefiting from their high ranging resolution. Distinct methods for estimating the spectral peak of beat frequency signal in frequency-domain have been proposed to improve the range resolution. Kim et al [18] proposed a low-complexity algorithm using two random beat signals to perform one-dimensional FFT for range detection Unlike those conditions presented in the above works, the ranging system and the target in our application are moving with a relative velocity and the range calculation time allowed is limited, requiring a real-time high-resolution estimation method. We proposed a time-domain ranging algorithm, essentially by calculating the ratio of the beat frequency signal to its derivative, and analyzed the inherent error of the proposed estimation in the case of spectral dispersion. The rest of this paper is organized as follows: In Section 2, we introduce the ranging model with beat frequency signal and propose a time-domain ranging method with detailed theoretical derivations.
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