A High Resolution Displacement Measurement System Based on Time-to-Digital Converter

Li, Cunlong; Chen, Weimin; Zhang, Peng; Zheng, Daqing; Chen, Shiyong; Yan, Rong Ge

doi:10.1109/lmwc.2014.2303168

Cited by 4 publications

(1 citation statement)

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“…At present, different kinds of ranging methods, such as continuous wave (CW) interferometry [ 4 ], ultra-wideband (UWB) [ 5 ], and frequency modulated continuous wave (FMCW) [ 6 ], have been proposed to achieve millimeter to sub-millimeter accuracy in the microwave and millimeter wave bands. Among them, CW radar based on interferometry in the time domain allows the measurement of relative change in distance with micrometer-level accuracy, but the unambiguous range limited by the wavelength is only in the order of centimeters [ 7 , 8 , 9 , 10 , 11 , 12 ]. As for UWB radar, the technologies of two-stage sampling, increasing the number of base stations, high-fidelity crystal oscillators, and carrier down conversion demodulation have been used to obtain the absolute distance measurement ability of centimeter accuracy within the range of tens of meters, or millimeter accuracy within the range of several meters [ 13 , 14 , 15 , 16 , 17 ].…”

Section: Introductionmentioning

confidence: 99%

Microwave Absolute Distance Measurement Method with Ten-Micron-Level Accuracy and Meter-Level Range Based on Frequency Domain Interferometry

Tang,

Jia,

et al. 2023

Sensors

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A microwave absolute distance measurement method with ten-micron-level accuracy and meter-level range based on frequency domain interferometry is proposed and experimentally demonstrated for the first time. Theoretical analysis indicates that an interference phenomenon occurs instantaneously in the frequency domain when combining two homologous broad-spectrum microwave beams with different paths, and the absolute value of the distance difference between the two paths is only inversely proportional to the period of frequency domain interference fringes. The proof-of-principle experiments were performed to prove that the proposed method can achieve absolute distance measurement in the X-band with standard deviations of 15 μm, 17 μm, and 26 μm and within ranges of 1.69 m, 2.69 m, and 3.75 m. Additionally, a displacement resolution of 100 microns was realized. The multi-target recognition performance was also verified in principle. Furthermore, at the expense of a slight decrease in ranging accuracy, a fast distance measurement with the single measurement time of 20 μs was achieved by using a digitizer combined with a Fourier transform analyzer. Compared with the current microwave precision ranging technologies, the proposed method not only has the advantages of high precision, large range, and rapid measurement capability, but the required components are also easily obtainable commercial devices. The proposed method also has better complex engineering applicability, because the ten-micron-level ranging accuracy is achievable only by using a simple Fourier transform without any phase estimation algorithm, which greatly reduces the requirement for signal-to-noise ratio.

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