Cable Detector principle of operation
Detector is used to locate submarine cables in water of up to 180
meters (100 fathoms) in depth.
A signal in the range of 4 Hz to 40 Hz is transmitted down the
submarine cable by an Electroding Generator such as the Tinsley type
5915 unit. This signal is picked up by a set of trailed probes
connected to the detector. The Detector and receiving probes are
normally aboard the repair ship, however, as they are portable, the
detector may be operated from any locally available ship or launch.
The received signal is processed and passed to the analogue front
panel meter and if fitted, chart recorder.
the Electroding Generator, Tinsley type 5915, is located in the
submarine cable terminal nearest to the fault area. The Electroding
Detector, Tinsley type 5916 is aboard the ship.
When the ship is in the vicinity of the cable area, the 5915
Electroding Generator is powered thus applying the low frequency
signal to the cable under test. At these frequencies, the field of the
signal extends into the water surrounding the cable for a considerable
The ship would normally steer a course to cross the cable on
the landward side of the expected fault position.
Before this position is reached, the ship launches the receiving
probe(s) which will then connect to the detector.
Detector is set (by thumbwheel switch) to the frequency being
transmitted by the Electroding Generator on shore. As the ship crosses
the cable, the field of the signal current on the cable induces a
voltage into the probe(s). This signal is then processed by the
Electroding Detector and a deflection on the meter is registered. This
may be recorded by the optional built-in chart recorder.
identification purposes, the Electroding Generator may be keyed on and
cable signal has been identified and confirmed, the ship then follows
the cable on a zigzag course until the signal disappears. When this
happens, the fault or break has been located.
Use of NAVSAT on a marker buoy would mark the point where the signal
was last detected.
Further probe runs may be made for a more precise fix of the fault