IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 48, NO. 3, JUNE 1999 773 Distributed Data Processing in a Telemetric System for Monitoring Civil Engineering Constructions Ali Iraqi, Student Member, IEEE, Roman Z. Morawski, Member, IEEE, Andrzej Barwicz, Member, IEEE, and Wojtek J. Bock, Senior Member, IEEE Abstract— The selected aspects of design methodology of a telemetric system for monitoring civil engineering constructions—using fiber-optic strain sensors—are considered. Particular attention is paid to the design decisions concerning the choice of a method for sensor calibration and measurand reconstruction, resulting requirements for computing power and their consequence on the distribution of data processing in the considered telemetric system. The results of this study may be applied for designing a specific telemetric system with fiber-optic sensors of strain. I. INTRODUCTION T HE continual monitoring of the distribution of strain in such civil engineering constructions as water dams, bridges, highways or landing surfaces in airports is of vital, technical and economic, importance. For example, there are today 187 000 deficient bridges in the National Bridge Inven- tory [1], this number steadily increases with age and about 1% (5000 bridges) become deficient each year. Techniques of nondestructive evaluation should be used effectively and efficiently to collect quantitative data about the condition of bridges and other elements of civil infrastructure. Many measurement techniques may be used for this purpose, e.g., magnetic-flux-leakage systems [2], strain gages and clinome- ters [3], or quantitative acoustic emission techniques [4]. In this paper, selected aspects of the design methodology of a telemetric system for monitoring civil engineering construc- tions, using fiber-optic strain sensors, are considered. Particular attention is paid to design decisions concerning the choice of a method for sensor signal processing, as well as to the resulting requirements for computing and telecommunication means. In Section II, the design methodology of telemetric systems is outlined. In Section III the configurations of telemetric systems are considered. The sensors and the selected procedures for measurement data processing are characterized in Section IV, and telecommunications links - in Section V. Section VI sum- marizes the obtained results, and Section VII contains some preliminary conclusions concerning the practical applicability Manuscript received May 21, 1998; revised February 22, 1999. This work was supported by the Natural Science and Engineering Council, Canada, and the State Committee for Scientific Research (KBN), Poland. Hewlett-Packard, Canada, contributed with equipment support. A. Iraqi and A. Barwicz are with the Department of Electrical Engineering, University of Qu´ ebec at Trois-Rivi` eres, C.P. 500 Trois-Rivi` eres, P.Q., G9A 5H7 Canada. R. Z. Morawski is with the Faculty of Electronics and Information Technol- ogy, Institute of Radioelectronics, Warsaw University of Technology, 00-665 Warsaw, Poland. W. J. Bock is with the Computer Science Department/Optoelectronics Laboratory, Universit´ e du Qu´ ebec ` a Hull, Hull, P.Q., J8Y 3X7 Canada. Publisher Item Identifier S 0018-9456(99)04983-9. Fig. 1. A two-level telemetric system for monitoring civil engineering constructions. of the obtained results in telemetric systems for monitoring civil engineering constructions. II. DESIGN METHODOLOGY OF TELEMETRIC SYSTEMS The design methodology of telemetric systems for mon- itoring civil engineering constructions is based on general principles of designing measuring systems—cf. [5]—and on several specific key decisions concerning the choice of the number and type of sensors, the scheme of their deployment on the monitored construction, the method for their calibration, the structure of the system, the type of telecommunications means and the method for data fusion and imaging. These decisions should be based on the analysis of the data streams to be processed in order to attain the objectives of monitoring, i.e., to provide the operator of the system with the desired information. Given the specification of this information, a de- signer has to make decisions to meet the requirements concern- ing accuracy and speed of measurement. The environmental parameters—such as temperature, humidity, etc.—influence the characteristics of sensors, and—consequently—the com- plexity of data processing required for attaining an acceptable accuracy of measurement. In this paper, two model situations are considered: • Case 1: Monitoring of indoor constructions (e.g., inside a building, a mine, or a tunnel) temperature of which is in the range 0 C–35 C. • Case 2: Monitoring of outdoor constructions (e.g., bridges or dams) temperature of which is in the range 50 C–50 C. III. TELEMETRIC SYSTEM CONFIGURATION A simple telemetric system for monitoring civil engineering constructions consists of a set of sensors deployed on the construction to be monitored, linked—via telecommunication means—with a computer-based central control unit (Fig. 1). 0018–9456/99$10.00  1999 IEEE