Wireless vehicle monitoring system

A method for communicating position data from a mobile unit carried by a vehicle to a control center of a vehicle monitoring system, said mobile unit comprising:

• a GPS receiver connected to a GPS antenna, said GPS receiver providing a first set of position information;
• a dead reckoning device providing a second set of position information;
• a signal processing unit for selecting between said first and second sets of position information;
• and
• a control and transmitting unit for retrieving said selected set of position information from said signal processing unit and transmitting said selected set of position information to said control center in a data packet transmitted over said communication interface in response to a request received from said control center,
• said method comprising the following steps, performed by said mobile unit:
• receiving a request from said control center to send a specified number of positions over a specified time interval;
• acquiring said number of positions from a positioning device in said mobile unit over said specified interval;
• accumulating said acquired positions;
• monitoring the quantity of unreported accumulated positions;
• and
• reporting said unreported accumulated positions in a data packet whenever said quantity of unreported accumulated positions reaches a predetermined data size.

An antenna cable for connecting an antenna, comprising:

• a first conductor for providing a DC voltage to a first terminal of said antenna;
• a second conductor for providing a ground reference to a second terminal of said antenna;
• and
• a third conductor having a first end and a second end, said first end being coupled to said second conductor to form a ground loop and, at said second end being available for connection to a continuity sensing circuit.