Failure Point Diagnostics in Cable Telemetry

A system for failure point diagnostics in cable telemetry at a wellsite, comprising:

• a cable defining a first round trip test loop, operatively coupling between a surface modem, comprising a first internal test loop, and a downhole modem, comprising a second internal test loop, that is operatively coupled to a downhole toolstring of one or more downhole tools via a toolbus defining a second round trip test loop;
• a surface computer, operatively coupled to the surface modem, that generates a plurality of surface test signals;
• a surface acquisition front-end, operatively coupled to the surface computer, that comprises a third internal test loop;
• wherein the surface computer is configured to sequentially apply the plurality of test signals across the first, second and third internal test loops and generate a failure point alert when at least one of the plurality of test signals fails in at least one of the test loops identifying which component of the cable telemetry system caused the test signal to fail.