Method of estimating bit error due to lightning surge taking into account arrester operation

The bit errors caused by the lightning surge contain one triggered by the operation of the lightning arrester installed in communication equipment and one caused by the superposition on the signal voltage the lightning surge (transverse lightning surge) appearing between two conductor wires due to the unbalance of the telecom system. In this paper, a method of estimating and evaluating the bit error by simulation (numerical calculation) is proposed in which these two bit errors are taken into account. By means of the proposed method, the average bit error per thunderstorm day by the lightning surge in the subscriber terminal of the AMI bit digital transmission system was derived. It was found that the bit error due to the operation of the arrester is proportional to -1.8 power of the operating voltage of the arrester while the bit error due to the transverse lightning surge is proportional to -1.8 power of the threshold level. The bit error at the time of appearance of the lightning can be substantially larger than the bit error inherent to the digital transmission system. Further, the relationship between the number of samples used in the simulation and the estimation error was studied. It was found that the adequate number of samples is 50 to 100.