A method and apparatus for accurately decoding a Manchester data stream having transition time distortion and noise spikes. Briefly, in an embodiment using a protocol where a falling edge at the mid-point of a bit represents a "1" bit and a rising edge at the mid-point represents a "0" bit, the coded data can be accurately determined by comparing the time period tp₁ from the start of the bit to the first falling edge and the time period tp₂ from the last rising edge to the end point of the bit. If tp₁ is less than tp₂, the bit represents a bit value of "0" and if tp₂ is less than tp₁, the bit represents a bit value of "1".