DM16E1 / DM4E1 Operation and Installation Manual - 204-4001-19
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Figure 14. BERT generation and reception at the digital interface
The BERT test pattern is generated towards the aggregate and is thus transmitted to the remote
equipment.
This test can be used together with a local analog loopback, local digital loopback or physical connection.
BERT can also be activated between two units that are in communication. In this case, each receiver
monitors the pattern sent by the other unit’s transmitter. Note that the pattern transmitted by the two units
should be the same.
5.6. Local Digital Loopback – LDL
This loopback is used to test the external link and the two data transmission directions. The figure below
shows the test conditions.
Figure 15. Local digital loopback at the digital interface
5.7. Operation via Terminal
The V.35 interface can be used in two directions: to the routing interface or to the aggregate.
To select the aggregate direction, the indicator “V” should be placed in the appropriate position in the
aggregate map, as shown in figure below. Note that if another interface is selected in the remote unit (an
E1 tributary, for example), interface conversion will be automatic. Further details on aggregate map
configuration can be found in chapter 3.10.3.
When directed to the router, the V.35 interface identifier should not appear in the tributary table. The V.35
interface is also disabled in the other status and test menus. In operation with the router, the V.35 interface
always regenerates the clock that should be supplied by the DTE through CT113 (configuration similar to
CT104 controlled, described below). The rate is regulated by the DTE and should not exceed 2 Mbit/s. For
details on how to configure the V.35 to the router, see chapter 0.
If the router is directed to a structured E1 channel in the aggregate, the V.35 should be disabled (absent
from the tributary table).
