Error detection for fiber distributed interfaced optic link

Claim 3

The method of claim 1, wherein the check code created is a plurality of parity bits, each parity bit being calculated over the N/M bits occupying corresponding bit positions.

Claim 4

The method of claim 1, wherein the check code is transmitted following transmission of the plurality of bits.

Claim 5

In a data communication system for communicating N-bit packets of digital data, including at least two bits indicative of one of a plurality of data types, apparatus to detect the presence of data corruption that may occur during transmission, the apparatus comprising: first circuit means for swapping a one of the two bits with a one of the remaining N bits, and including encoding means for creating a check code that is derived from N/M bits that occupy corresponding bit positions of N/M groups of the N bits; transmitting means coupled to the first circuit means for receiving and serially transmitting the N bits and the check code in a FDDI 4B/5B format; receiving means coupled to receive the 4B/5B encoded N bits and check code, including means to extract the N bits and the check code from the FDDI 4B/5B format, and means for creating from the received N bits an error code in the same manner as the check code was created; and second circuit means comparing the error and the check codes to provide an indication of error when the error and check codes do not match.

Claim 6

In a data communication system for communicating N-bit packets of digital data, including at least two bits indicative of one of a plurality of data types, apparatus to detect the presence of data corruption that may occur during transmission, the apparatus comprising: first circuit means for swapping a one of the two bits with a one of the remaining N bits, and including encoding means for creating a check code that is derived from N/M bits that occupy corresponding bit positions of N/M groups of the N bits; transmitting means coupled to the first circuit means for receiving and serially transmitting the N bits and the check code in a FDDI 4B/5B format; receiving means coupled to receive the 4B/5B encoded N bits and check code, including means to extract the N bits and the check code from the FDDI 4B/5B format, and means for creating from the received N bits an error code in the same manner as the check code was created; and second circuit means comparing the error and the check codes to provide an indication of error when the error and check codes do not match.

Claim 7

The apparatus of claim 4, wherein N=20.

Claim 8

The apparatus of claim 5, wherein M=5.

Claim 9

The apparatus of claim 4, wherein the transmitting means includes means for transmitting the FDDI 4B/5B encoded N bits and check code as a number of individual data words.

Claim 10

The apparatus of claim 5, wherein the receiving means includes means for returning the swapped bits to their original locations in the N bit packet prior to creating the error code.

Claim 11

In a data communication system for communicating N-bit packets of digital data, including at least two bits indicative of one of a plurality of data types, a method of detecting the presence of data corruption which may occur during transmission, the method comprising the steps of: swapping of one of the two bits with a one of the remaining N bits; creating a check code that is derived from N/M bits that occupy corresponding bit positions of N/M groups of the N bits; serially transmitting the N bits and the check code in a FDDI 4b/5b format; receiving the 4B/5B encoded N bits and check code, and extracting the N bits and the check code from the FDDI 4B/5B format; creating from the received N bits an error code in the same manner as the check code created; and comparing the error and the check codes to provide an indication of error when the error and check codes do not match.

Claim 12

In a data communication system for communicating N-bit packets of digital data, including at least two bits indicative of one of a plurality of data types, a method of detecting the presence of data corruption which may occur during transmission, the method comprising the steps of: swapping of one of the two bits with a one of the remaining N bits; creating a check code that is derived from N/M bits that occupy corresponding bit positions of N/M groups of the N bits; serially transmitting the N bits and the check code in a FDDI 4b/5b format; receiving the 4B/5B encoded N bits and check code, and extracting the N bits and the check code from the FDDI 4B/5B format; creating from the received N bits an error code in the same manner as the check code created; and comparing the error and the check codes to provide an indication of error when the error and check codes do not match.