US Patent 7861083 Hybrid encoding of data transmissions in a security system

A security system in which wireless transmitting security devices use a hybrid or dual encoding methodology, wherein a first part of a data message is encoded in a return-to-zero (RZ) format and a second part of the data message is encoded in a non-return-to-zero (NRZ) format, thereby increasing error detection and correction. In a first aspect of the invention, status information is included in the first part of the message and redundant status information is included in the second part of the message. In a second aspect of the invention, message sequence information is included in the second part of the message to avoid processing of stale or out-of-sequence messages.