9
you are using two Model 2707s together as short-range modems, set
both units to HDB3.
Switch S1-3: Line Build-out Impedance
Switch S1-3 is used to select line build-out (LBO) impedance for the Model
2707’s E1 port. Your Model 2707RC comes equipped with either an RJ-48C
connector, dual BNC connectors, or both. When connecting to the E1 net-
work, the LBO selection must match the connector type. If the dual BNC con-
nectors are used, the line build-out impedance must be set to 75-ohm.
Otherwise, for the RJ-48C connector, impedance should be set to 120 ohm.
S1-6 and S1-7 Clock Modes
Set switch S1-6 and S1-7 to determine the 2707RC’s transmitter timing.
Table 2:
S1-1 Line Coding settings
S1-1
Line Coding
Off
HDB3
On
AMI
Table 3:
S1-3 Line Build-out settings
S1-3
Setting
75 ohm
On
120 ohm
Off
Table 4:
S1-6 and S1-7 Clock Modes
S1-6
S1-7
Clock Mode
On
On
Network (Received Recovered)
On
Off
Internal
Off
On
External
Off
Off
Network (Received Recovered)
Network Clock
Transmitter timing is derived using the received
line signal (received recovered) from the network.
Internal Clock
Transmitter timing is derived from an internal clock
source.
External Clock
Transmitter timing is derived from DTE terminal
timing. (Units equipped with 10Base-T modules do
not operate in external clock mode. They enter
internal clock mode when this setting is selected.)
