The coax pinger later evolved into the TDR (time domain reflectometer) which included a calibrated time base and compensation for various cable's velocity factor. (Ex.: fused disc cable is different than solid dielectric.) TDR's are used extensively by CATV companies to locate faults especially underground.
The TDR has since evolved into the OTDR (optical time domain reflectometer) which is used for Fiber "cable".
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