| 摘要 |
Disclosed is a telematics system that is self-contained and includes a numbe r of anti-defeat counter-measure features that prevent the disablement of the system. In addition, the present system utilizes event sensors, such as moti on sensors, to detect the existence of an event after the remote unit has been armed. Location data is then sent to a base station that calculates if the unit has been moved beyond a predetermined perimeter which causes the generation of a alarm condition. The telematics system is also capable of adjusting the transmission frequency period of location data that is sent fr om the remote unit by eleminating redundant data. Transmission rates of the dat a are maximized by adjusting the baud rate according to the signal strength of a communication link between the remote unit and a base station. The base station is capable of generating dead reckoning data from raw direction and speed data as well as GPS location data provided by the remote unit. Dual antennas are provided that minimize space requirements by placing both the G PS antenna and a cellular phone antenna on a single substrate, printed circuit board. An isolation fence is provided between the antennas to isolate the electromagnetic waves. Voltage supplies are also monitored by the remote uni t to determine if an external power supply has been cut or if the vehicle battery is dead.
|
