4B3T

MMS43 Code (Modified Monitored Sum 43 - code ) is a line code in the field of telecommunications. Here (bits ), three ternary ( three-valued ) values ​​with the levels of four binary values ​​- formed, 0 and . It is therefore 4B3T code (4 Binary Ternary 3 ) mentioned.

The coding is achieved, the DC freedom in the power density spectrum of the transmission signal. This is particularly necessary in order that the signal may in the usual telephone network exchanger pass. The coding, however, adds to the signal relative redundancy of 0.159 added.

The 4B3T coding is mainly used for the UK0 subscriber lines for ISDN basic rate access.

DC component suppression

In order to achieve the DC Freedom, the transmitter / encoder follows the previously accumulated DC component and used for some of the 16 possible input words different output words, so that the total accumulated DC component remains limited.

The following output words are direct component and do not change the accumulated DC component:

The following output words have a DC component, so any input word, two output words assigned ( a "positive " and " negative " ):

• Line code