Abstract:

A new design of guarding against burglary of electric cables based on monitoring the variety of capacitance of the lamps on the road is introduced in this paper.Nowadays the lamps on the road usually have large compensated capacitance,so the capacitance of the cable will change with the length of the cable.The new system is based on the rule above to measure the capacitance to find the exact position where the stealing happened by the use of the single chip AT89C51.Voice chip ISD25120 & dialing chip MT8888 are used to give an alarm on the telephone line automatically.

Key words: cable guard;DTMF;voice chip;singlechip;autoalarm