Definition: Gray code

A binary code used to represent digits generated from a mechanical sensor that may be prone to error. Used in telegraphy in the late 1800s, and also known as "reflected binary code," Gray code was patented by Bell Labs researcher Frank Gray in 1947.

Only Change One Bit
In Gray code, there is only one bit location different between numeric increments, which makes mechanical transitions from one digit to the next less error prone. The following chart shows normal binary representations from 1 to 10 and the corresponding Gray code.

    Decimal  Binary   Gray
    Digit    Code     Code

       0     0000     0000
       1     0001     0001
       2     0010     0011
       3     0011     0010
       4     0100     0110
       5     0101     0111
       6     0110     0101
       7     0111     0100
       8     1000     1100
       9     1001     1101
      10     1010     1111