Abstract: A telemetry receiver which is capable of automatically recognizing certain incompatible code formats and correctly decoding received data from a remotely located telemetry transmitter is disclosed. The specific embodiment is an end of train receiver mounted in the cab of a locomotive which receives encoded transmissions, including encoded brake pipe pressure data, a transmitter mounted on the last car of a train. The receiver permits telemetry equipment to be "mixed-and-matched"; that is, the receiver in the locomotive will respond to the transmissions of a telemetry transmitter attached to the last car of the train no matter what the vendor source. The telemetry receiver is provided with a microprocessor which analyzes the received transmission. The microprocessor is programmed to recognize certain known transmission protocols and formats and then invoke the correct routine for decoding the received data.

Abstract: A technique for redundantly encoding data for synchronous or asynchronous serial transmission or recording and the correlative technique for decoding the serial bit stream are disclosed. The encoding technique involves making the second data string of a data string pair the complement of the first data string and formatting to the format H.sub.1 Data H.sub.2 Data where H.sub.1 and H.sub.2 are headers wherein at least one bit is the same in corresponding bit positions of the headers. Decoding involves first detecting the headers and then checking to confirm that the data fields are complements. Also disclosed is a technique for extracting bits from the data stream.