remote digital ioopback towards the remote user dte. the ioopback is performed by connecting at the local fcd-2 the data channel receive signal to the data channel transmit input after the el framer, as shown in figure 5-5. 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 local fcd-2 el interface and framer, and the transmission plant connecting the two fcd-2s.

    the test ioopback can be activated only when the internal di3g jumper is set to on (see section 2.4 for details).