PD IEC/TR 63094:2017 pdf free.Multimedia systems and equipment-Multimedia signal transmission – Dependable line code with error correction.
4.1 Overview
The line code 4b/10b handles a 10-bit frame encoded by 4-bit digits. The original 4 bits of information digits are encoded into a 10-bit frame by the look-up table shown in Table 1. A byte (8 bits) is divided into two half bytes (4b). A half byte (4b) is encoded to a symbol (10b).
A frame consists of a symbol and is transmitted to the communication line. Since four bits are encoded to ten bits by the 4b/10b line code, the communication speed at 1 000 MHz is approximately equal to 400 Mbit/s.
4.2 Forward error correction (FEC)
The line code 4b/10b should provide error-free transmission for reliable real-time control.Error correction should be performed by hardware. The 4b/10b performs line-code-level error correction. Original four-bit data (4b) are encoded to 10-bit transmitting data with embedded clock, DC balance, 2-bit error detection, and 1-bit error correction for a half byte of data (4 bits of information digits).The Hamming distance of any digits in a symbol (10b code) is longer than or equals 4 for 1-bit error correction and 2-bit error detection.
4.3 Embedded clock
The line code 4b/10b ensures that successive 0 bits or 1 bits are within five bits, even if a 1- bit error/symbol occurs. Characteristics of the embedded clock are shown in Annex B.In the case of inside symbol digits, successive 0 bits or 1 bits are within five bits.In the case of inter-symbol digits, successive 0 bits or 1 bits are within five bits.When each symbol has 1-bit error, if the distance of error bits is greater than four-bit, the successive 0 or 1 bits are within five bits. In the case of two-bit errors, discontinuity of digits is not guaranteed.
4.4 DC balance
In order for the line code 4b/10b not to allow a current to flow in the communication cable, the numbers of 0 and 1 in a symbol are same for DC balance. But DC balance between successive symbols is not necessary. Characteristics of the DC balance are shown in Annex C.PD IEC/TR 63094 pdf download.