Ignition spark advance using a constant peak to peak amplitude timing

Abstract

A phase-lock loop ties a reference input frequency such as for the rotational speed of an engine with an engine timing signal. The engine timing signal is a sawtooth with a peak to peak amplitude and with the phase of the timing signal corresponding to the instantaneous amplitude of the timing signal between its peak to peak extremes. The phase-lock loop comparison, produces a drive or speed signal which is also indicative of the reference signal frequency. The level of the drive or speed signal, is that necessary to maintain the period of the timing signal in correspondence with the reference input signal. A third signal may be generated, proportional to the engine rotational speed signal, or to any other engine parameter which is compared to the timing signal to produce a trigger signal at the appropriate phase angle of the engine rotational cycle.