The indicator is based on Akram El Sherbini's article "Time Cycle Oscillators" published in IFTA journal 2018.
The simple harmonic index (SHI) is based on the derivations of the simple harmonic equation
The trading tactic used for the simple harmonic index is merely the centerline crossover. A buy signal is generated when the SHI line moves above the zero level to turn positive. The period of the bull cycle rises, leading to an increase in price displacement. A sell signal is generated when the SHI line crosses down the centerline to turn negative.