A. determines that the outdoor antenna is aimed at the base station.           

B. determines that the communication distance between the outdoor antenna and the base station is within 5 km.            

C. determines that the cables of the outdoor antenna and amplifier are not more than 40 meters, not less than 10 meters, and confirm that the cable is up to the standard.            

D. If has not been solved, replace the high-power amplifier or the professional personnel.