1) Check the E1/T1 cable on the BSC interface board.
a. Check whether the length of the E1 cable is greater than 7.5 m and whether the length of the T1 cable is greater than 10 m.
Y => If the length of the E1 cable is greater than 7.5 m or if the length of the T1 cable is greater than 10 m, go to 2).
N => If the length of the E1 cable is smaller than 7.5 m or if the length of the T1 cable is smaller than 10 m, go to b.
b. Check whether the E1 cable or T1 cable is a shielded cable and whether the shielded connector is used.
Y => The E1 cable or T1 cable is a shielded cable and the shielded connector is used. Then, go to c.
N => The E1 cable or T1 cable is not a shielded cable or the shielded connector is not used. Then, go to d.
c. Check whether the E1 cable or T1 cable is grounded.
Y => The E1 cable or T1 cable is grounded. Then, go to 2).
N => The E1 cable or T1 cable is not grounded. Then, go to e.
d. Replace the E1 cable or T1 cable with a shielded cable, or replace the common connector with a shielded connector. Then, go to 2).
e. Ground the E1 cable or T1 cable properly and then go to 2).
2) Check whether both the BSC and the DDF that is connected to the BSC are grounded.
Y => Both the BSC and the DDF that is connected to the BSC are grounded. Then, go to 4).
N => Both the BSC and the DDF that is connected to the BSC are not grounded or neither the BSC nor the DDF that is connected to the BSC is grounded. Then, go to 3).
3) Ensure that all the equipment is grounded. Then, go to 4).
4) Use a multimeter to check whether the grounding voltage of the BSC and of the DDF that is connected to the BSC is zero.
Y => The grounding voltage is zero. The BSC, peer NE, and DDF between the BSC and the peer NE are properly grounded.
N => The grounding voltage is not zero. The BSC, peer NE, and DDF between the BSC and the peer NE are improperly grounded. Then, go to 5).
5) Ensure that all the equipment is properly grounded.