Mr. suggested a way to improve trend identification using high-pass filters. The basic smoothers like , low-pass filters, have considerable lag in their display. Mr. applied the high-pass filter and subtracted the high-pass filter output from the time series input. Doing these steps he removed high-frequency short-wavelength components (the ones causing the wiggles) from the time series.
As a result he got a special series of the low-frequency components with virtually no lag - the Decycler.
The Decycler is plotted with two additional lines (the percent-shifts of Decycler) and together they form a hysteresis band.
If the prices are above the upper hysteresis line, then the market is in an uptrend. If the prices are below the low hysteresis line, then the market is in a downtrend. Prices within the hysteresis band are trend-neutral.