| 摘要 |
System for securing objects, especially vehicles, comprising a) in or on the object: a GPS-receiver which is able to supply data determining the position on the earth where the object is located, a transmitter for transmitting these position determining data through a communication channel of a wireless telephone network, b) in a central post: a receiver for receiving the data tranmitted by said transmitter through said wireless telephone network. Between the GPS-receiver and the transmitter on or in said object there is a coder for coding the data supplied by the GPS-receiver in combinations of tone frequency signals which thereafter are transmitted by said transmitter. In the central post the receiver is followed by a decoder for decoding the received tone frequency signals into suitable data signals. Each of said tone frequency signals has a frequency which is within the band width, avilable within said telephone network for each communication channel and has a time length sufficient to enable an error-free detection in said receiver even in the presence of short disturbances and noise within the communication channel. |
