A method of decoding a biphase mark coded (BMC) data stream. A BMC encoded signal (BMC signal) including a preamble and data payload is received at a receiver which includes a BMC decoder state machine (state machine). The preamble is processed using the state machine including measuring a total duration spanning at least three transitions to provide a ≧2 UI duration measure, a calculated 0.75 UI duration value (0.75 UI duration value) is generated from the ≧2 UI duration measure, and the 0.75 UI duration value is compared to a programmed UI range. Provided the 0.75 UI duration value is within the programmed UI range data, respective bits are extracted bit-by-bit from the data payload using the 0.75 UI duration value to obtain unencoded data.