G.703/G.704 NTU W/V35
19
Figure 6. Local Loopback for a Network Termination Application
To perform a LL test, follow these steps:
1. Activate LL. This may be done in one of two ways:
— Place the switch on the front panel in the “Local” position.
— Activate the “LL” signal on the DTE. If you are not sure which lead is
the “LL” signal, please refer to Appendix B.
2. Verify that the data terminal equipment is operating properly and can be
used for a test.
3. Perform a V.52 BER (bit error rate) test as described in section “Using the
V.52 (BER) Test Pattern Generator” on page 21. If the BER test equipment
indicates no faults, but the data terminal indicates a fault, follow the manu-
facturer’s checkout procedures for the data terminal. Also, check the inter-
face cable between the terminal and the MT335A.
4.9.32 O
PERATING
R
EMOTE
D
IGITAL
L
OOPBACK
(RL)
The Remote Digital Loopback (RL) test checks the performance of both the local
and remote MT335A, as well as the communication link between them. Any
characters sent to the remote MT335A in this test mode will be returned back to
the originating device (i.e, characters typed on the keyboard of the local terminal
will appear on the local terminal screen after having been passed to the remote
MT335A and looped back).
Serial
Device
Serial
Device
MT335A
Receive
Recover
Clocking
Internal
Clocking
Cable Span
G.703/G.704 NTU
MT335A
G.703/G.704 NTU
MT335A
Clock/
Data
Clock/
Data
Clock/
Data
Data
Data
MT335A
