An Ultrasonic Object Detection Applying the ID Based on Spread Spectrum Technique for a Vehicle†
1
Department of Electrical and Computer Engineering, Pusan National University, 2, 63beon-gil, Busandaehakro, Geumjeong-Gu, Busan 46241, Korea
2
Department of Naval Architecture and Ocean Engineering, Pusan National University, 2, 63beon-gil, Busandaehakro, Geumjeong-Gu, Busan 46241, Korea
*
Author to whom correspondence should be addressed.
†
This paper is an extended version of two conference papers published in: Donghee Yi; Jaehan Joo; Suk Chan Kim. Implementation of DPSK-based Obstacle Detection System using UItrasound for Vehicles. In Proceedings of the 11th International Conference on Ubiquitous and Future Networks (ICUFN 2019), Split, Croatia, 2–5 July 2019; Donghee Yi; Jaehan Joo; Zewen Piao; Heetae Jin; Suk Chan Kim. Ultrasound-based Obstacle Detection System for Vehicles under Interference Environment. In Proceedings of the 25th Asia-Pacific Conference on Communications (APCC 2019), Ho Chi Minh City, Vietnam, 6–8 November 2019.
Sensors 2020, 20(2), 414; https://doi.org/10.3390/s20020414
Received: 15 December 2019 / Revised: 3 January 2020 / Accepted: 8 January 2020 / Published: 11 January 2020
(This article belongs to the Special Issue Selected Papers from the 3rd Global IoT Summit)
When an ultrasonic sensor generates an ultrasonic wave and detects an obstacle from a reflected wave, a signal transmitted by other ultrasonic sensors would be interference. In this paper, to overcome the interference, a transducer transmits a signal with a unique ID modulated. The interference is ignored by verifying that the reflected signal includes its ID. The ID verification process uses a correlation between the received signal and the ID. Therefore, the ID is selected from orthogonal codes with good cross-correlation. Long code has the advantage of being more robust to interference. However, the reflected wave from nearby obstacles might return before the transmission ends. Therefore, the 7-bit Barker code is applied for near obstacle detection and a 31-bit Gold code is used for distant obstacle detection. The modulation technique is DQPSK, which is available in a narrow bandwidth and has a simple receiver structure. In ID recognition based on correlation, a near–far problem occurs due to a large amplitude difference between the received wave and interference. The addition of a zero-crossing detector solves this problem. The hardware is implemented based on the algorithm proposed in this paper. The simulation showed a detection rate of at least 90% and the the result of the real measurement represented a detection rate of 97.3% at 0.5 m and 94.5% at 2 m.
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Keywords:
ultrasound; detection; DSSS; orthogonal code; DQPSK
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MDPI and ACS Style
Yi, D.; Jin, H.; Kim, M.C.; Kim, S.C. An Ultrasonic Object Detection Applying the ID Based on Spread Spectrum Technique for a Vehicle. Sensors 2020, 20, 414. https://doi.org/10.3390/s20020414
AMA Style
Yi D, Jin H, Kim MC, Kim SC. An Ultrasonic Object Detection Applying the ID Based on Spread Spectrum Technique for a Vehicle. Sensors. 2020; 20(2):414. https://doi.org/10.3390/s20020414
Chicago/Turabian StyleYi, Donghee; Jin, Heetae; Kim, Moon C.; Kim, Suk C. 2020. "An Ultrasonic Object Detection Applying the ID Based on Spread Spectrum Technique for a Vehicle" Sensors 20, no. 2: 414. https://doi.org/10.3390/s20020414
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