pseudo ternary method
The pseudo-ternary method is a transmission method for baseband systems that works in the same way as the bipolar method, in which the logical "1" is alternately assigned the transmission amplitude "+A" and "-A".
The pseudoternary code knows three signal states: positive level, no level and negative level. The difference to the bipolar method is that the square pulse becomes shorter than the step duration. This has the advantage that the decay of the step is decayed until the next pulse. In contrast, the zero level in the ternary method is fixed as a voltage potential. The ternary method knows the levels -1, 0 and +1.
The pseudo ternary method is used in ISDN. In the USA, the pseudoternary method has been replaced by the 2B1Q coding.