| 摘要 |
SECURE TRANSMISSION FOR REMOTE CONTROL AND SUPERVISION SYSTEMS A transmission protocol for use in transmitting commands to an end of train (EOT) device controls a train's brake system. A head of train (HOT) device, typically located in the locomotive cab, is provided with a thumbwheel switch for inputting numbers which identify the EOT device. In the simplest implementation, the EOT device will respond to any HOT that dials its number and it will do whatever it is told to do. To prevent dangerous commands from being executed in error, either several repetitions of the command must be sent to the EOT device by the HOT device within a predetermined period of time before the command, or the command takes the form of a very large predefined number or a combination of the two. The next level of security requires only a minimum increase in circuit complexity. A memory is added to the EOT device and a unique ID number is assigned to the HOT device. The HOT unique ID is communicated to the EOT device during an arming sequence, and the unique ID is imbedded in the memory of the EOT. Once armed, with the HOT unique ID stored in the memory, the EOT device will respond only to that particular HOT device. Security is increased by replacing the unique ID of the HOT device with a "password". The password can consist of a very large (32 bits) number that has the mathematical characteristic of being the product of one unique pair of prime numbers.
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