Data communication, with improved error detection, of a signal having a plurality of data blocks, by: error checking a received data block in a first sequence using a first polynomial, beginning with a first predetermined initial error checking state, producing a first CSUM; error checking the received data block in a second sequence using a second polynomial, using the first CSUM as a second predetermined initial error checking state, producing a second CSUM; comparing the second CSUM to the first predetermined initial error checking state to detect errors in the data communication; and repeating the above steps for sequential data blocks of the data communication, wherein the first polynomial is an inverse of the second polynomial.