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 IRP notation: {40k,2300,msb}<-1|1>(255:8,X:24,0:4)+
 EFC translation: MSB of decoded signal.

This is an unusual protocol in that an 8-bit device code and 8-bit OBC are encoded in a 24-bit error-correcting code as the X of the IRP notation. This is constructed as follows. First two parity bits are appended to the 16 data bits to give even parity for the two sets of 9 bits taken alternately. The resulting 18-bit sequence is then treated as 6 octal digits (0-7) expressed in 3-bit binary code. These are then re-coded in the 3-bit Gray code (also called, more descriptively, the reflected-binary code) with a parity bit to give odd parity, so giving 6 4-bit groups treated as a single 24-bit sequence. The whole thing allows any single-bit error in transmission to be identified and corrected.

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