When multiple current interrupters are employed on a pipeline, their internal clocks must be synchronized in order to guarantee "in-phase" current switching so that accurate instant-off potentials can be recorded.
With "non-GPS" current-interrupter units, in order to achieve (initial) clock synchronization, all participating units have to be brought together in one place. Furthermore, because of clock-drift due to local temperature variations and other effects, the clocks in the participating units can quite quickly drift out of synchronization, which leads to "out-of-phase" current waveforms.
The ideal scenario is one in which current-interrupter units can be left in the field for indefinite periods of time (with no external power source required) and their internal clocks will always be synchronized with each other during critical time periods, such as periods of repetitive current interruption (current cycling periods).
Our GPS Current-Interrupter (the Cronos unit) satisfies both of these "ideal-case" requirements.
The Cronos unit does not require an external power supply and it can run applications for years at a time using an internal battery power source. This is possible due to the advanced design of the Cronos unit which results in extremely-low power consumption, even when the unit is tracking GPS satellites.