High Precision Opto-Acoustic BPSK-CDMA Distance Measurement for Object Tracking

Esslinger, Dominik; Rapp, Philipp; Sawodny, Oliver; Tarín, Cristina

doi:10.1109/smc.2018.00493

Cited by 9 publications

(6 citation statements)

References 20 publications

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“…It has the same advantages in multiple access and is easy to implement in ultrasonic systems. OOK [5,32], PSK [33,38], and FSK [39,40] are used to modulate and demodulate digital codes into analog signals.…”

Section: Existing Keying Code Division Multiple Accessmentioning

confidence: 99%

“…Faster R-CNN [33,42] consists of a convolutional neural network (CNN) backbone to obtain the features of segmented spectrogram signals, a region proposal network (RPN) to propose a time-frequency domain region, and a classification network to classify the code and heterogeneous signal. The CNN backbone receives the segmented spectrogram of the received ultrasonic signal as the input and extracts the spatial features through convolution.…”

Section: Code Classification Using Faster Region-based Cnnmentioning

confidence: 99%

“…The performance of the frequency sweep keying method using the Faster R-CNN proposed in this paper was compared with the traditional modulation methods OOK, FSK, and PSK and the correlation-based frequency sweep keying method previously proposed by our research team. For comparison with other modulation methods, OOK used the modulation/demodulation method of [5], FSK used the modulation/demodulation method of [33], and PSK used the modulation/demodulation method of [34]. The root mean square (RMS) and standard deviation of the TOF error were measured in the millisecond scale.…”

Section: Robustness Comparison For Homogeneous Signal With Other Modu...mentioning

confidence: 99%

“…These methods offer robust decoding against environmental noise, but lead to the deterioration of the orthogonality of the code due to demodulation errors occurring when signals from different nodes overlap. The authors of [33] used BPSK to measure indoor distance. A cross-correlation-type demodulator was applied to improve the decoding performance.…”

Section: Introductionmentioning

confidence: 99%

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Improved Frequency Sweep Keying CDMA Using Faster R-CNN for Extended Ultrasonic Crosstalk Reduction

Park,

Baek

2023

Sensors

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Ultrasonic sensors are inexpensive and provide highly accurate measurements, even with simple hardware configurations, facilitating their use in various fields. When multiple ultrasonic sensors exist in the measurement space, crosstalk occurs due to other nodes, which leads to incorrect measurements. Crosstalk includes not only receiving homogeneous signals from other nodes, but also overlapping by other signals and interference by heterogeneous signals. This paper proposes using frequency sweep keying modulation to provide robustness against overlap and a faster region-based convolutional neural network (R-CNN) demodulator to reduce the interference caused by heterogeneous signals. The demodulator works by training Faster R-CNN with the spectrograms of various received signals and classifying the received signals using Faster R-CNN. Experiments implementing an ultrasonic crosstalk environment showed that, compared to on–off keying (OOK), phase-shift keying (PSK), and frequency-shift keying (FSK), the proposed method can implement CDMA even with shorter codes and is robust against overlap. Compared to correlation-based frequency sweep keying, the time-of-flight error was reduced by approximately 75%. While the existing demodulators did not consider heterogeneous signals, the proposed method ignored approximately 99% of the OOK and PSK signals and approximately 79% of the FSK signals. The proposed method performed better than the existing methods and is expected to be used in various applications.

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Section: Existing Keying Code Division Multiple Accessmentioning

confidence: 99%

Section: Code Classification Using Faster Region-based Cnnmentioning

confidence: 99%

Section: Robustness Comparison For Homogeneous Signal With Other Modu...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Improved Frequency Sweep Keying CDMA Using Faster R-CNN for Extended Ultrasonic Crosstalk Reduction

Park,

Baek

2023

Sensors

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show abstract

“…Although this device is triggered electronically, the sound generation mechanism is governed by fluid turbulences and cannot be controlled precisely, resulting in jitter in the 10–100

s range. Additionally, if the reference signal is insufficiently modeled, the correlation result gives erroneous information about the actual ToF [ 30 , 31 ]. Direct measurement is then the appropriate method for obtaining an accurate reference signal.…”

Section: Introductionmentioning

confidence: 99%

Development of an Accurate and Robust Air-Coupled Ultrasonic Time-of-Flight Measurement Technique

Bühling

Küttenbaum

Maack

et al. 2022

Sensors

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Ultrasonic time-of-flight (ToF) measurements enable the non-destructive characterization of material parameters as well as the reconstruction of scatterers inside a specimen. The time-consuming and potentially damaging procedure of applying a liquid couplant between specimen and transducer can be avoided by using air-coupled ultrasound. However, to obtain accurate ToF results, the waveform and travel time of the acoustic signal through the air, which are influenced by the ambient conditions, need to be considered. The placement of microphones as signal receivers is restricted to locations where they do not affect the sound field. This study presents a novel method for in-air ranging and ToF determination that is non-invasive and robust to changing ambient conditions or waveform variations. The in-air travel time was determined by utilizing the azimuthal directivity of a laser Doppler vibrometer operated in refracto-vibrometry (RV) mode. The time of entry of the acoustic signal was determined using the autocorrelation of the RV signal. The same signal was further used as a reference for determining the ToF through the specimen in transmission mode via cross-correlation. The derived signal processing procedure was verified in experiments on a polyamide specimen. Here, a ranging accuracy of <0.1 mm and a transmission ToF accuracy of 0.3μs were achieved. Thus, the proposed method enables fast and accurate non-invasive ToF measurements that do not require knowledge about transducer characteristics or ambient conditions.

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Simultaneous Opto-Acoustic 3D Pose Estimation of Multiple Objects with Near-Far Mitigation for Economical Indoor Localization

Esslinger

Rapp

Sawodny

et al. 2019

2019 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM)

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High Precision Opto-Acoustic BPSK-CDMA Distance Measurement for Object Tracking

Cited by 9 publications

References 20 publications

Improved Frequency Sweep Keying CDMA Using Faster R-CNN for Extended Ultrasonic Crosstalk Reduction

Improved Frequency Sweep Keying CDMA Using Faster R-CNN for Extended Ultrasonic Crosstalk Reduction

Development of an Accurate and Robust Air-Coupled Ultrasonic Time-of-Flight Measurement Technique

Simultaneous Opto-Acoustic 3D Pose Estimation of Multiple Objects with Near-Far Mitigation for Economical Indoor Localization

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