Patent ID: 7027524

Claim:
A method of transmitting QPSK digital signals in which each 2-digit binary number, referred to as a symbol, is assigned a phase of a carrier, each of the four 2-digit binary numbers corresponds to a quadrant of the complex plane, and supplementary binary digits generated in accordance with an error correcting product code are added to a set of binary digits to enable error correction at the receiver, said method comprising the steps of: placing I and Q bits of a 2-digit symbol to be transmitted in different rows but in the same column, so that each row contains only one type of bit, I or Q; effecting the error correction coding row by row and then by pairs of adjacent columns; deducing the code I bits of two associated adjacent columns from the I bits of said two columns; deducing the code Q bits of said two associated adjacent columns from the Q bits of said columns; disposing said coded bits so that each row contains only one type of bit, I or Q; and transmitting the pairs adjacent code I and Q bits in the same column along with the 2-digit symbols to be transmitted.