ALARMS, TROUBLESHOOTING & TESTING
20
4. 3 Test Loop
DC3000
DC3000
LOCAL
DTE
REMOTE
DTE
Tx
Figure 4.3 Test loop on local DC3X00
Set the local DC3X00 base panel bit-switch labelled
TEST LOOP
to the
ON
position. When
the
TEST LOOP
is activated at the local DC3X00, the signal received at the E1 port is
passed directly back to the link at the line interface. The signal from the DTE is looped
adjacent to the DTE port. This effectively isolates the DC3X00 running the test and validates:
(a) the local DTE cable if the local DTE recognises its own transmissions.
(b) the remote DTE and its cable, the remote DC3X00 and the E1 link if the remote DTE
recognises its own transmissions.
LOCAL
DTE
DC3000
DC3000
REMOTE
DTE
Figure 4.4 Test loop on remote DC3X00
Set the remote DC3X00 base panel bit-switch labelled
TEST LOOP
to the
ON
position.
The test loop validates:
(a) the remote DTE cable if the remote DTE recognises its own transmissions.
(b) the local DTE and its cable, the local DC3X00 and the E1 link if the local DTE
recognises its own transmissions.
