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Communications Handbook for Traffic Control Systems

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Communications Handbook for Traffic Control Systems Communications Handbook for Traffic Control Systems NOTE TO READER: THIS IS A LARGE DOCUMENT Due to its large size, this document has been segmented into multiple files. All files separate from this main document file are accessible from links (blue type) in the table of contents or the body of the document. Communications U.S Department of Transportation Handbook for Traffic Federal Highway Administration Control Systems TRANSMISSION LINK OR CHANNEL (PHYSICAL CONNECTION OR AIR PATH MEDIA) TRANSMITTERTRANSMITTER RECEIVERRECEIVER (DISTORTION) MODULATORMODULATOR DEMODULATORDEMODULATOR NOISENOISE SOURCESOURCE INFORMATIONINFORMATION DESTINATIONDESTINATION SOURCESOURCE (CONTROLLER)(CONTROLLER) (COMPUTER)(COMPUTER) Publication No. FHWA-SA-93-052 April 1993 Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. FHWA-SA-93-052 4. Title and Subtitle 5. Report Date April 1993 Communications Handbook for Traffic Control Systems 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Robert L. Gordon, Robert A. Reiss, Walter M. Dunn and David R. Morehead 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Dunn Engineering Associates 66 Main Street 11. Contract or Grant No. Westhampton Beach, NY 11978 AT&T Bell Laboratories, Holmdel, NJ 07733 DTFH71-91-C-00038 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Office of Technology Applications Final Report - Oct 1991-Feb 1993 Federal Highway Administration 14. Sponsoring Agency Code 400 Seventh Street, SW Washington, DC 20590 15. Supplementary Notes FHWA Contract Manager (COTR): Jeffrey Lindley (HPD-09) 16. Abstract This handbook was written to enable transprotation engineers to plan, select,design, implement, operate maintain communication systems for traffic control. It has been designed to aid: - Transportation officials overseeing traffic control systems; - Communications engineers; and - Traffic control systems engineers. The handbook provides information on communications media, system architectures, decision-making processes, and trade-off analyses. The handbook will serve as a guide for agencies wiching to: - Initiate a traffic control system that incorporates functional, effective, realiable and economical communications. - Update and modemize an existing communications system for traffic control. 17. Key Words 18. Distribution Statement Communications, traffic control, fiber optic, No restrictions. This document is available coaxial cable, twisted wire pair, to the public through the National Technical communications standards Information Service, Springfield, VA 22161 19. Security Classif. (of this report) 20.Security Classif. (of this page) 21. No of Pages 22. Price Unclassified Unclassified Form DOT F 1700.7(8-72) Reproduction of completed page authorized TABLE OF CONTENTS CHAPTER 1 - INTRODUCTION COMMUNICATIONS......................................................................................................1-1 NEED FOR HANDBOOK................................................................................................1-1 PURPOSE OF HANDBOOK............................................................................................1-2 ORGANIZATION OF HANDBOOK..................................................................................1-2 CHAPTER 2 - FUNDAMENTALS INTRODUCTION..............................................................................................................2-1 NEED ..............................................................................................................................2-1 PURPOSE........................................................................................................................2-2 ORGANIZATION..............................................................................................................2-2 ELEMENTS......................................................................................................................2-2 INFORMATION SOURCE..............................................................................................2-2 Information..........................................................................................................2-2 SIGNALS..........................................................................................................................2-6 MODULATION.............................................................................................................. 2-8 Amplitude Modulation........................................................................................ 2-8 Frequency Modulation...................................................................................... 2-8 Phase Modulation............................................................................................ 2-10 TRANSMISSION LINK OR CHANNEL...................................................................... 2-10 Bandwidth, Attenuation and Power Budget.................................................... 2-10 MULTIPLEXING ........................................................................................................ 2-14 Frequency Division.......................................................................................... 2-14 Time Division.................................................................................................... 2-14 Code Division.................................................................................................. 2-19 NOISE AND INTERFERENCE.................................................................................... 2-19 Noise................................................................................................................ 2-19 Interference...................................................................................................... 2-19 Signal to Noise Ratio and Bit Error Rate........................................................ 2-20 ERROR DETECTION AND CONTROL .................................................................... 2-20 Automatic Repeat Request.............................................................................. 2-20 Forward Error Control...................................................................................... 2-23 DATA TRANSMISSION AND LINK CONTROL.......................................................... 2-23 Modes.............................................................................................................. 2-23 Techniques...................................................................................................... 2-23 Link Control...................................................................................................... 2-25 HISTORICAL PERSPECTIVE.................................................................................... 2-25 CHAPTER 3 - FIELD EQUIPMENT INTERFACES INTRODUCTION..............................................................................................................3-1 NEED ..............................................................................................................................3-1 PURPOSE........................................................................................................................3-2 ORGANIZATION..............................................................................................................3-2 ELECTROMECHANICAL CONTROLLERS....................................................................3-2 ELECTRONIC AND NEMA TS1 CONTROLLERS........................................................3-2 Remote Communications Unit............................................................................3-5 NEMA TS2 CONTROLLERS..........................................................................................3-5 TYPE 170/179 CONTROLLERS....................................................................................3-5 ADVANCED TRAFFIC CONTROLLERS...................................................................... 3-8 CHANGEABLE MESSAGE SIGNS (CMS).................................................................. 3-8 DETECTION DEVICES................................................................................................ 3-9 HIGHWAY ADVISORY RADIO (HAR).......................................................................... 3-9 CHAPTER 4 - COMMUNICATIONS REQUIREMENTS INTRODUCTION..............................................................................................................4-1 NEED ..............................................................................................................................4-1 PURPOSE........................................................................................................................4-2 ORGANIZATION..............................................................................................................4-2 REQUIREMENTS FOR DATA COMMUNICATION...................................................... 4-2 Short Polling Cycles and Limited Field Storage Capability ................................4-2 Long Polling Times and Robust Field Storage Capability.............................. 4-10 Contention Techniques.................................................................................... 4-12 Trunking and Distribution System.................................................................... 4-15 Communication Overhead Burdens................................................................ 4-17 COMMUNICATIONS REQUIREMENTS
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