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Swiss Army Knife Indicator

Ehlers DSP filter ehlers dsp multi-purpose smoothing

A versatile indicator that can be configured as EMA, SMA, Gaussian, Butterworth, High Pass, Band Pass, or Band Stop filter.

Usage

Use as a single configurable filter that can emulate SMA, EMA, Gaussian, Butterworth, or bandpass responses by switching mode flags. Ideal for prototyping different filter designs without code changes.

Background

Ehlers presents the Swiss Army Knife Indicator in Cycle Analytics for Traders as a unified filter framework. A set of boolean flags selects the operating mode, making it possible to compare multiple filter responses on the same data by simply toggling flags rather than reimplementing each filter.

Parameters

  • mode (default: BandPass): Filter mode (EMA, SMA, Gauss, Butter, Smooth, HP, 2PHP, BP, BS)
  • period (default: 20): Filter period
  • delta (default: 0.1): Bandwidth parameter for BP and BS modes

Formula

\[ Filt = c_0(b_0 x_t + b_1 x_{t-1} + b_2 x_{t-2}) + a_1 Filt_{t-1} + a_2 Filt_{t-2} - c_1 x_{t-N} \]

Source