A periodic or cyclic signal whose cycles mark the passage of time. (A clock signal may, but does not necessarily, give the time of day.) In electronics, a traditional clock signal is usually a square wave or pulse wave. Some particular part of the signal, often the "rising edge" (when the signal goes from its low extreme to its high extreme) is designated as the "reference" point; the occurrence of this part of the signal marks an increment of time. In electronic music, clock signals are most commonly used to coordinate musical events which the performer desires to be synchronized in time. These might include:
- Forcing a reset of a VCO or LFO (that is, forcing it to return to a specific point in its cycle)
- Initiating the attack phase of an envelope generator in a cyclic fashion
- Triggering a sample and hold to latch a new sample of the input signal
- Causing a sequencer or drum machine to advance to its next step, or increment of time
Besides a plain square wave, two types of clock signal that are often used in electronic music are DIN sync and MIDI Clock.
