Radio communication security system - has mobile transceivers, each using dedicated code which is decoded at main station from call number

摘要

The communication system has decoders/coders in mobile transceivers and employs different codes for different transceivers or groups of transceivers. The main station has a decoder/coder whose code is set by the call number of the called transceiver or by the identifier of responding transceiver. The code of a transceiver is fixed by a coding plug, which also codes the selective call, the identifier and the information being sent. The main station has a comparator circuit for comparing incoming call numbers with call numbers retained in a memory. The comparator controls the setting of the main station coder/decoder. The system provides secure communication links.