Cable testing device and testing method thereof

A cable testing method for testing the sheltering performance of a cable, the cable having a central wire, a shelter wrapped around the central wire and an exterior cover wrapped around the shelter, the method comprising the steps of:

• firstly, the cable to be tested being placed in a metal tube, one end of the metal tube being connected with an output of a network testing device, the other end of the metal tube being earthed;
• secondly, one end of a central wire of the cable being earthed, meanwhile, the two ends of the shelter also being earthed, the other end of the central wire of the cable being connected with an input of the network testing device;
• next, the output of the network testing device transmitting signals to change the charges on the surface of the metal tube, as a result, an electromagnetic field being formed in the interior of the metal tube;
• then, the input of the network testing device receiving electromagnetic induction signals inducted by the central wire of the cable;
• and
• lastly, the network testing device analyzing the electromagnetic induction signal inducted by the central wire placed in the metal tube, then deciding the sheltering performance of the shelter of the cable.