Phase Lock

Any of a number of processes used to help synchronize signals or devices by correcting phase differences. For example, in analog tape machines, phase locking helps to keep multiple machines synced together by sensing phase differences in the playback of pilot tunes by the two machines and adjusting the speed to eliminate the phase difference. In synthesizers, phase locking controls one tone generator so that it begins its waveform in phase with the signal from another tone generator. Phase-locked loops (PLL) are reference signals used in the clock functions of electronic devices.