Next Article in Journal / Special Issue
Real Time Cascade Impactor Based On Surface Acoustic Wave Delay Lines for PM10 and PM2.5 Mass Concentration Measurement
Previous Article in Journal
Social Incentive Mechanism Based Multi-User Sensing Time Optimization in Co-Operative Spectrum Sensing with Mobile Crowd Sensing
Previous Article in Special Issue
Single Interdigital Transducer Approach for Gravimetrical SAW Sensor Applications in Liquid Environments
Article Menu
Issue 1 (January) cover image

Export Article

Open AccessArticle
Sensors 2018, 18(1), 246; https://doi.org/10.3390/s18010246

Acoustic Transducers as Passive Cooperative Targets for Wireless Sensing of the Sub-Surface World: Challenges of Probing with Ground Penetrating RADAR

1
Franche-Comté Électronique, Mécanique, Thermique et Optique—Sciences et Technologies (FEMTO-ST), 15B Avenue des Montboucons, 25000 Besançon, France
2
SENSeOR SAS, 505 route des Lucioles, 06560 Valbonne, France
3
Frec|n|sys SAS, 18 Rue Alain Savary, 25000 Besançon, France
*
Author to whom correspondence should be addressed.
Received: 20 November 2017 / Revised: 2 January 2018 / Accepted: 15 January 2018 / Published: 16 January 2018
(This article belongs to the Special Issue Surface Acoustic Wave and Bulk Acoustic Wave Sensors)
Full-Text   |   PDF [7532 KB, uploaded 17 January 2018]   |  

Abstract

Passive wireless transducers are used as sensors, probed by a RADAR system. A simple way to separate the returning signal from the clutter is to delay the response, so that the clutter decays before the echoes are received. This can be achieved by introducing a fixed delay in the sensor design. Acoustic wave transducers are ideally suited as cooperative targets for passive, wireless sensing. The incoming electromagnetic pulse is converted into an acoustic wave, propagated on the sensor substrate surface, and reflected as an electromagnetic echo. According to a known law, the acoustic wave propagation velocity depends on the physical quantity under investigation, which is then measured as an echo delay. Both conversions between electromagnetic and acoustic waves are based on the piezoelectric property of the substrate of which the sensor is made. Investigating underground sensing, we address the problems of using GPR (Ground-Penetrating RADAR) for probing cooperative targets. The GPR is a good candidate for this application because it provides an electromagnetic source and receiver, as well as echo recording tools. Instead of designing dedicated electronics, we choose a commercially available, reliable and rugged instrument. The measurement range depends on parameters like antenna radiation pattern, radio spectrum matching between GPR and the target, antenna-sensor impedance matching and the transfer function of the target. We demonstrate measurements at depths ranging from centimeters to circa 1 m in a sandbox. In our application, clutter rejection requires delays between the emitted pulse and echoes to be longer than in the regular use of the GPR for geophysical measurements. This delay, and the accuracy needed for sensing, challenge the GPR internal time base. In the GPR units we used, the drift turns out to be incompatible with the targeted application. The available documentation of other models and brands suggests that this is a rather general limitation. We solved the problem by replacing the analog ramp generator defining the time base with a fully digital solution, whose time accuracy and stability relies on a quartz oscillator. The resulting stability is acceptable for sub-surface cooperative sensor measurement. View Full-Text
Keywords: acoustic transducer; surface acoustic wave; cooperative target; wireless sensing; ground-penetrating RADAR acoustic transducer; surface acoustic wave; cooperative target; wireless sensing; ground-penetrating RADAR
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
SciFeed

Share & Cite This Article

MDPI and ACS Style

Friedt, J.-M.; Martin, G.; Goavec-Mérou, G.; Rabus, D.; Alzuaga, S.; Arapan, L.; Sagnard, M.; Carry, É. Acoustic Transducers as Passive Cooperative Targets for Wireless Sensing of the Sub-Surface World: Challenges of Probing with Ground Penetrating RADAR. Sensors 2018, 18, 246.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Sensors EISSN 1424-8220 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top