Abstract: A location or other description of the source of a transmission is inserted into the communication as a prefix to transmitter data. A multi-format receiver emits a sequence of different handshakes until the transmitter begins to respond. The receiver stores the prefix and a descriptor of the last handshake prior to the transmitter response. Subsequent signals with a stored prefix are greeted immediately with the stored associated handshake.

Abstract: A digital alarm receiver interacts with a multiplicity of transmitters having a plurality of different transmitter formats. The receiver adapts automatically to different formats received over the same input line. A series of different handshake signals are emitted by the receiver until a response is evoked. The received message is displayed and a record of the message as well as a description of the resulting action taken by the operator are printed. Messages which normally arrive at predetermined times are handled by the receiver without requiring any operator action. A failure of an expected message to arrive, or the arrival of a message outside its expected time slot, result in an alarm condition which requires operator action.