The LTUC (Line Trunk Unit Control) board provides the interface between the converter for the signaling channel DCL, the switching network CN and the peripheral boards of the LTU shelf. This board implements the switchover from redundant central sytem units to the non-redundant periphery and the electrical conversion and decoupling.
In the LTUC, the lines for the speech channels, signaling channels, clock lines and reset signals are converted from balanced to imbalanced signals and transferred from the currently active control to the peripheral board with the shelf, and vice versa.
The LTUC board Q2028 processes four speech channels (2 MHz) on the periphery side and four speech channels (2 MHz) on the switching network side. The LTUC board Q2128 processes eight speech channels (2 MHz) on the periphery side and four speech channels (4 MHz) on the switching network side.