Abstract: 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.