Patent ID: 6411074
Filing Date: 2002-06-25
Classification: G01R

Abstract:
A signal injecting apparatus for use in locating an undersea cable comprising:processing means for generating a square wave signal having a set frequency; first and second switching means connected to said processing means, said first and second switching means providing power up/down signals when an operator depresses said first and second switching means; said processing means, responsive to said power up/down signals, providing a digital word representative of a power level for a tracking signal which said signal injecting apparatus injects into said undersea cable; gating means having a first input connected to said processing means for receiving said square wave signal, a second input and an output; a field effect transistor having a gate connected to the output of an inverter driver, a current sense output, and a drain, said field effect transistor providing a current level signal representative of a drain current being supplied to the drain input of said field effect transistor; converting means connected to said processing means for receiving said digital word and converting said digital word to an equivalent analog signal; control loop circuit means having a first input connected to the current sense output of said field effect transistor to receive said current level signal, a second input connected to said converting means to receive said equivalent analog signal and an output connected the second input of said gating means; said control loop circuit means, responsive to said equivalent analog signal and said current level signal, providing an enable signal to said gating means to enable said gating means allowing said square wave signal to pass through said gating means to the gate of said field effect transistor turning said field effect transistor on and off at the set frequency of said square wave signal; a signal injector coil connected to the drain of said field effect transistor in response to said square wave signal from said field effect transistor when said gating means is enabled; and said signal injector coil, responsive to said square wave signal, generating said tracking signal, said signal injector coil being coupled to said undersea cable to inject said tracking signal into said undersea cable.