Vehicle tracking, communication and fleet management system

摘要

A vehicle fleet management information system for identification of location and direction of movement of each vehicle in the fleet in real-time and automatic communication directly with management offices to report its location and heading, and status of predetermined events in which the vehicle may be engaged. Each fleet vehicle is assigned a unique time slot to transmit its reporting information over a communications network without substantially interfering with transmissions from other vehicles in their own respective time slots. Precise time synchronization is provided by a timing control PLL which provides timing corrections as necessary from GPS based time reference. The network includes a dual band full-duplex interface with TDMA on one-half of the interface and broadcast on the other half. Additionally, time processing units of microprocessors in components throughout the network perform precise clock synchronization. A protocol is established for entry by vehicle transmitters into the network in the assigned time slots for periodic transmission of messages, and space diversity is performed on messages received from the vehicle transmitters to avoid data corruption. Different periodic transmission intervals are provided for different vehicles in the network by dynamically allocating the slots for various update rates. And auxiliary reporting slots are provided to allow prompt reporting of important data by the respective vehicle transmitters independent of slower periodic transmission intervals. Baseband filtering of data reduces the occupied bandwidth of the transmission channel, and includes removal of synchronization data to minimize overhead of non-information bearing data. Certain repeated events in which the vehicle is operated according to basic usage and specific usage for its industry are sensed, detected or measured and automatically reported to management offices.