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. One example is a cement delivery truck which monitors location, speed and status information such as start pour, pouring, end pour, wash and leave job, and automatically transmits this information with a management office without requiring affirmative action by the vehicle operator.

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.

Abstract: A vehicle fleet management information system identifies location and direction of movement of each vehicle in a fleet in real-time, and automatically reports such information, as well as status of predetermined events in which the vehicle is engaged, directly to the fleet manager. Each fleet vehicle has an assigned time slot to transmit its reporting information over a communications network without interfering with transmissions from other vehicles in their own respective time slots. A timing control phase lock loop (PLL) provides precise time synchronization for timing corrections from a global positioning system (GPS) based time reference. A dual band full-duplex interface of the network has TDMA on one-half and broadcast on the other half. Microprocessor time processing units in components of the network perform precise clock synchronization. Space diversity performed on received vehicle transmitted messages avoids data corruption.

Abstract: A computer (20) includes a hardware memory access enforcer (50) to insure that various independent programs (52, 54) operating on the computer (20) follow isolated processing rules. Each program has its own memory domain (56), which may extend across instruction, data, and I/O memory spaces (40, 42, 44). A system controller program (52) is a trusted process. The system controller (52) may access memory in the domain (56) of any application (54), and program flow may exit system controller (52) to any application (54). However, applications (54) cannot access memory outside of their own domains (56), and program flow may not exit applications (54) to enter other applications (54). Program flow may exit applications (54) to system controller (52) only if directed to an entry address (60). A tracking circuit (74) verifies that a microprocessor (22) actually executes entry instructions (94) located at the entry address (60).