NCJ Number
12233
Date Published
1973
Length
62 pages
Annotation
SYSTEMS WHICH AUTOMATICALLY DETERMINE AND MAKE AVAILABLE TO A CENTRAL POINT THE POSITION OF EACH MEMBER OF A GROUP OF VEHICLES.
Abstract
AVM SYSTEMS USED IN URBAN APPLICATIONS ARE BASED ON FOUR BASIC TECHNIQUES--RADIO PROPAGATION TIME, PROXIMITY, DEAD RECKONING, AND TRIANGULATION. LOCATION TECHNIQUES BASED ON RADIO PROPAGATION TIME ASSUME THE DISTANCE BETWEEN A TRANSMITTER AND A RECEIVER CAN BE DERIVED FROM A MEASUREMENT OF THE TIME TAKEN BY THE SIGNAL TO TRAVEL FROM ONE TO THE OTHER. PROXIMITY TECHNIQUES DEPEND ON DETECTING THAT THE VEHICLE IS ADJACENT TO AN OBJECT WHOSE POSITION IS ALREADY KNOWN. TRIANGULATION PROVIDES VEHICLE LOCATION BY MEASURING THE BEARING OF TRANSMISSIONS FROM THE VEHICLE RECEIVED AT A NUMBER OF FIXED SITES WHOSE GEOGRAPHICAL POSITIONS ARE KNOWN. DEAD RECKONING, REFERS TO THE USE OF DISTANCE-TRAVELED AND DIRECTION MEASUREMENTS FOR COMPUTING A VEHICLE'S LOCATION RELATIVE TO A KNOWN STARTING POINT. FOLLOWING AN OPENING DISCUSSION OF AVM APPLICATIONS, THE RELATIVE MERITS OF THE TECHNIQUES ARE DISCUSSED AND, WHERE TEST OR SIMULATION DATA AND COST INFORMATION ARE AVAILABLE, THESE TOO ARE PROVIDED. ALSO INCLUDED IS A DISCUSSION OF SECONDARY SYSTEMS' FUNCTIONS (POLLING, COMPUTATION, TELEMETRY, ETC.) THAT MUST BE ADDRESSED BEFORE A WORKABLE AVM SYSTEM CAN BE IMPLEMENTED. AN APPENDIX SUMMARIZES THE COST FOR ONE SPECIFIC AVM SYSTEM. ADDITIONAL MATERIAL INCLUDES SYSTEM ILLUSTRATIONS AND CHARTS OF TEST RESULTS. (SNI ABSTRACT)