remote analog loopback towards the remote user dte. the ioopback is performed by connecting at the local fcd-2 the regenerated receive signal to the transmit input of the main link interface, as shown in figure 5-4. the test signal is provided by the remote user dte that must receive its own transmission. this test checks the connections to the remote dte, all the circuits of the remote fcd-2, the ltu functions of the local and remote fcd-2s, and the transmission plant connecting the two fcd-2s.

    the test loopback can be activated only when the internal dbg jumper is set to on (see section 2.4 for details).