CABLE TESTING

摘要

A pulse echo equipment is provided for automatically impedance matching test leads. Test pulses are applied to test leads and switches 10 and 12 are selectively closed for different short periods of time. The average voltage developed during those periods is applied via a comparator 30 to allow clock pulses to be counted by a counter 34 and to vary the effective impedance of a matching circuit by supplying a current to a lamp 40. A light sensitive resistor 42 is part of the matching circuit of the equipment.