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Open AccessArticle

A Method of FPGA-Based Extraction of High-Precision Time-Difference Information and Implementation of Its Hardware Circuit

by Jian Li 1,2,*, Xinlei Yan 1, Maojin Li 1, Ming Meng 1 and Xin Yan 1
1
Shanxi Key Laboratory of Information Detection and Processing, North University of China, Taiyuan 030051, China
2
National Key Laboratory of Electronic Measurement Technology, North University of China, Taiyuan 030051, China
*
Author to whom correspondence should be addressed.
Sensors 2019, 19(23), 5067; https://doi.org/10.3390/s19235067
Received: 29 September 2019 / Revised: 17 November 2019 / Accepted: 18 November 2019 / Published: 20 November 2019
(This article belongs to the Section Sensor Networks)
The positioning technology to find shallow underground vibration sources based on a wireless sensor network is receiving great interest in the field of underground position measurements. The slow peaking and strong multi-waveform aliasing typical of the underground vibration signal result in a low extraction accuracy of the time difference and a poor source-positioning accuracy. At the same time, the transmission of large amounts of sensor data and the host computer’s slow data processing speed make locating a source a slow process. To address the above problems, this paper proposes a method for high-precision time-difference measurements in near-field blasting and a method for its hardware implementation. First, based on the broadband that is typical of blast waves, the peak frequency of the P-wave was obtained in the time–frequency domain, taking advantage of the difference in the propagation speed of the P-wave, S-wave, and the surface wave. Second, the phase difference between two sensor nodes was found by means of a spectral decomposition and a correlation measurement. Third, the phase ambiguity was eliminated using the time interval of the first break and the dynamic characteristics of the sensors. Finally, following a top-down design idea, the hardware system was designed using Field Programmable Gate Array(FPGA). Verification, using both numerical simulations and experiments, suggested that compared with generalized cross-correlation-based time-difference measurement methods, the proposed method produced a higher time-difference resolution and accuracy. Compared with the traditional host computer post-position positioning method, the proposed method was significantly quicker. It can be seen that the proposed method provides a new solution for solving high-precision and quick source-location problems, and affords a technical means for developing high-speed, real-time source-location instruments. View Full-Text
Keywords: time difference; distributed source location; first break arrival time time difference; distributed source location; first break arrival time
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Li, J.; Yan, X.; Li, M.; Meng, M.; Yan, X. A Method of FPGA-Based Extraction of High-Precision Time-Difference Information and Implementation of Its Hardware Circuit. Sensors 2019, 19, 5067.

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