Exalt Communications, Inc.
r-series
Installation and Management Manual
5000007 (ETSI)
53
2007-02-12 (draft)
External loopback modes are used in conjunction with an external test source. The designation of
‘local’ or ‘remote’ refers to where the loopback is occurring relative to the location where the
loopback is implemented. That is, on the radio being accessed, if External (remote) is selected,
this loops the signal back at the remote radio interface back towards the local radio. Likewise, if
External (local) is selected, the signal loops back at the local interface towards the remote radio
(Figure 22 and Figure 23).
Figure 22
External (remote) loopback
Figure 23
External (local) loopback
When a local T1/E1 port is configured for External (remote) loopback, it is the same as
configuring the remote radio for External (local) loopback.
Internal loopback uses an internal test source, and sends the test source signal across the link,
looped at the remote radio’s interface, returned to the local radio, and looped at the local radio’s
interface back to the source. The inputs at both ends are looped back at the line level. Figure 24
illustrates the internal loopback function.
Figure 24
Internal loopback
LOCAL
REMOTE
IN
OUT
OUT
IN
LOCAL
REMOTE
IN
OUT
OUT
IN
LOCAL
REMOTE
IN
OUT
OUT
IN