By adsorbing many high-tech achievements, GAO-8B, as a portable and multi-functional automatic communication cable-fault tester, is widely chosen by the line-checking workers to accurately localize the fault and also applied in the fields of measurement and acceptance of line engineering and the works of line maintenance and the checking of electrical characterizes of cable, especially in the fields of the localization of faults of core wire such as breakage, misconnection, geothermy, water absorption, and poor insulation, easy operation and excellent performance of which enable you to be a cable testing expert.