1) Measuring device 2) Measuring instrument 3) Measuring system 4) Synchroniser 5) Synchronizer 6) Synchronoscope 1) Synchroniser 2) Synchronizer 3) Synchronoscope 
In AC electrical power systems, a synchroscope is a device that indicates the degree to which two systems (generators or power networks) are synchronized with each other. For two electrical systems to be synchronized, both systems must operate at the same frequency, and the phase angle between the systems must be zero (and two polyphase systems mu...
instrument for detecting whether two moving parts are synchronized
instrument intended to indicate that two alternating voltages or polyphase voltage systems have the same frequency and are in phase
[n] - an instrument that indicates whether two periodic motions are synchronous (especially an instrument that enables a pilot to synchronize the propellers of a plane that has two or more engines)
An instrument for indicating whether two engines are running at the same speed.
synchronoscope noun an instrument that indicates whether two periodic motions are synchronous (especially an instrument that enables a pilot to synchronize the propellers of a plane that has two or more engines)
an instrument for determining the difference in phase between two related motions, as those of two aircraft engines or two electric generators.