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sent through the optical link, so that they are accurate only when the optical receiving is
working in good condition.
4.2. DIP-switches Configuration
4.2.1. Dip-switches for E1 Interface Impedance
There are 8 groups of 4-bit dip-switches, SW1 to SW8. These switches
cannot be managed by network management software, so they must be
set manually.
Definition as shown below
st
nd
1
2
ON
ON
75Ω unbalanced signal effective
As shown in figure above, the default status is set as "75Ω unbalanced signal BNC
interface effective".
•
When adopting 75 Ohm unbalanced signal, it is required to plug a DB37 to 8 CC3
coaxial adapter, which is of CC4B-8G type. This adapter can convert DB37 connector
to 8 CC3 coaxial connectors, for input and output of 4 E1 channels.
•
When adopting 120 Ohm balanced signal, it is required to first set the dip-switches as
per the above tables. 37-pin connector shall be used to connect the twisted-pair cables
for DB37 connector. Please refer to Appendix A for details of sequence of twisted-pair
and cable making.
4.2.2. DIP-switch for Function Configuration
There is a 6-bit dip-switch SW10 on the PCB.
st
th
•
1
~ 4
: Loop-back control
st
1
bit
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
Note: Only two test method can be set: single E1 channel loop-back or all E1 channels
loop-back. When single E1 channel loop-back is testing, the other channels are working
normally without disturbance.
The network management software can send out the loop-back enable/disable command,
and they have high priority to the settings by hardware.
rd
th
3
4
ON
OFF
nd
2
bit
OFF
OFF
OFF
OFF
ON
ON
ON
ON
OFF
ON
st
1
Or
OFF
120Ω balanced signal effective
rd
th
3
bit
4
bit
OFF
OFF
OFF
ON
ON
OFF
ON
ON
OFF
OFF
OFF
ON
ON
OFF
ON
ON
OFF
OFF
ON
ON
7
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ON
OFF
nd
rd
2
3
OFF
OFF
ON
OFF
1 2 3 4 5 6
Loop-back
No
loop-back
st
1
E1
nd
2
E1
rd
3
E1
th
4
E1
th
5
E1
th
6
E1
th
7
E1
th
8
E1
All E1 links
1 2 3 4
th
4
ON
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