Description of the problem

At a project site, there are E1 services between the transmission SDH equipment and the wireless BSC/BTS/DBS, and E1 cables between the transmission and wireless equipment need to be deployed. However, the E1 cable on the side of the transmission SDH equipment is configured with an impedance of 120 ohms, and the E1 cable on the side of the wireless BSC/BTS/DBS equipment is configured with an impedance of 75 ohms, and the two can not be directly docked using the BNC interface.

The E1 cable of the transmission device OSN 3500 is 120 ohm as shown below:

The E1 cable for the wireless device BSC/BTS/DBS is 75 ohms, as shown below:

Alarm message

None

Processing

120 ohm cable and 75 ohm E1 cable can not be directly docked using BNC connectors, in the middle of the need for a 120 ohm to 75 ohm adapter, where the 120 ohm connector for the RJ-45 crystal head, 75 ohm connector for the BNC connector.

The picture of the adapter is as follows:

The overall docking picture on site is as follows:

Root cause

None

Recommendations and conclusions

It is recommended that both pre-sales product lines be configured with E1 cables of the same impedance.

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