The device also provides the functions of receive equalization (optional), automatic-gain control (AGC), clock-recovery and data retiming, loss-of-signal and loss-of-frequency-lock detection. The digital system interface is dual-rail, with received positive and negative 1s appearing as unipolar digital signals on separate output leads. The on-chip equalizer is designed for cable distances of 0 to 450ft. from the cross-connect frame to the device. The receive input has a variable input sensitivity control, providing three different sensitivity