Data bus: Organizing a data communications system for buses is no easy task - alternatives should be tried before purchase wherever possible

摘要

Citywide deployments of bus location technologies, covering thousands of buses in suburban and dense urban areas, are becoming more common. In the past these used a hodgepodge of bespoke technologies such as beacons and customized analog PMR. Today the emphasis is, very wisely, on using commercial off the shelf (COTS) technologies to reduce the cost of procurement and maintenance. GPS has been flavor-of-the-month for some years and, more recently, packet data over GSM cellular (general packet radio service or GPRS) is starting to be taken seriously as a contender. Neither of these technologies was designed for fleet management GPS was developed for battlefield conditions - good sky view and minimal ground clutter, GPRS and the cellular networks it runs over was developed for consumer grade services - games, email downloads and so on, So using them for fleet management should be approached cautiously Experience in citywide GPS shows that it doesn't always go to plan, though re-cent technological advances have smoothed over some of the rough spots.