SMPTE RP 165:1994

Abtract:

(1.1) This practice, also known as the error detection and handling (EDH) system, describes the generation of error detection checkwords and related status flags to be used optionally in conjunction with the serial digital interface for system M (525/59.94) and systems B, G, H, and I (625/50) digital television equipment operating with either 13.5-MHz or 18-MHz sampled 4:2:2 component digital signals or 4fsc composite digital signals. Although it is preferred that this error-checking method be used in all serial transmitters and receivers, it is recognized that some equipment must minimize complexity. Additionally, there is nothing in this practice which should preclude its use in a parallel digital interface for 4:2:2 component digital signals. (1.2) Two checkwords are defined: one based on a field of active picture samples and the other on a full field of samples. This two-word approach provides continuing error detection for the active picture when the digital signal has passed through processing equipment that has changed data outside the active picture area without recalculating the full-field checkword. (1.3) Three sets of flags are provided to feed forward information regarding detected errors to help facilitate identification of faulty equipment and the type of fault. One set of flags is associated with each of the two field related check-words. A third set of flags is used to provide similar information based on evaluating all of the ancillary data checksums within a field. Implementation of these flags is not a requirement of this practice. (1.4) The checkwords and flags are combined in an error detection data packet which is included as ancillary data in the serial digital signal. At the receiver, a recalculation of check-words may be compared to the error detection data packet information to determine if a transmission error occurred.