The Detrended Ehlers Leading Indicator(DELI) was authored by Jon Ehlers (See “MESA and Trading Market Cycles” by John Ehlers).
Detrended Synthetic Price is a function that is in phase with the dominant cycle of real price data. This one is computed by subtracting a 3 pole Butterworth filter from a 2 Pole Butterworth filter. Ehlers Leading Indicator gives an advanced indication of a cyclic turning point. It is computed by subtracting the simple moving average of the detrended synthetic price from the detrended synthetic price.