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[blackcat] L2 Ehlers Simple Decycler
Level: 2
Background
John F. Ehlers introuced Simple Decycler in Sep, 2015.
Function
In “Decyclers” in Sep, 2015, John Ehlers described a method for constructing an oscillator that could help traders detect trend reversals with almost no lag. Ehlers calls this new oscillator a decycler. The author began the process by isolating the high-frequency components present in the input data. He then subtracted these from the input data leaving only the lower-frequency components representing the trend. In more details, the idea is to subtract the high-pass filter value from the current close to get a “decycled” indicator that follows the trend rather well by removing much of the distracting high-frequency chatter. Apply a second high-pass filter using half the period from the first filter to the decycled indicator and you get a smoother result with much-reduced lag.
Key Signal
Decycle --> Ehlers Simple Decycler signal or center line of band
Pros and Cons
100% John F. Ehlers definition translation, even variable names are the same. This help readers who would like to use pine to read his book.
Remarks
The 84th script for Blackcat1402 John F. Ehlers Week publication.
Readme
In real life, I am a prolific inventor. I have successfully applied for more than 60 international and regional patents in the past 12 years. But in the past two years or so, I have tried to transfer my creativity to the development of trading strategies. Tradingview is the ideal platform for me. I am selecting and contributing some of the hundreds of scripts to publish in Tradingview community. Welcome everyone to interact with me to discuss these interesting pine scripts.
The scripts posted are categorized into 5 levels according to my efforts or manhours put into these works.
Level 1 : interesting script snippets or distinctive improvement from classic indicators or strategy. Level 1 scripts can usually appear in more complex indicators as a function module or element.
Level 2 : composite indicator/strategy. By selecting or combining several independent or dependent functions or sub indicators in proper way, the composite script exhibits a resonance phenomenon which can filter out noise or fake trading signal to enhance trading confidence level.
Level 3 : comprehensive indicator/strategy. They are simple trading systems based on my strategies. They are commonly containing several or all of entry signal, close signal, stop loss, take profit, re-entry, risk management, and position sizing techniques. Even some interesting fundamental and mass psychological aspects are incorporated.
Level 4 : script snippets or functions that do not disclose source code. Interesting element that can reveal market laws and work as raw material for indicators and strategies. If you find Level 1~2 scripts are helpful, Level 4 is a private version that took me far more efforts to develop.
Level 5 : indicator/strategy that do not disclose source code. private version of Level 3 script with my accumulated script processing skills or a large number of custom functions. I had a private function library built in past two years. Level 5 scripts use many of them to achieve private trading strategy.
Background
John F. Ehlers introuced Simple Decycler in Sep, 2015.
Function
In “Decyclers” in Sep, 2015, John Ehlers described a method for constructing an oscillator that could help traders detect trend reversals with almost no lag. Ehlers calls this new oscillator a decycler. The author began the process by isolating the high-frequency components present in the input data. He then subtracted these from the input data leaving only the lower-frequency components representing the trend. In more details, the idea is to subtract the high-pass filter value from the current close to get a “decycled” indicator that follows the trend rather well by removing much of the distracting high-frequency chatter. Apply a second high-pass filter using half the period from the first filter to the decycled indicator and you get a smoother result with much-reduced lag.
Key Signal
Decycle --> Ehlers Simple Decycler signal or center line of band
Pros and Cons
100% John F. Ehlers definition translation, even variable names are the same. This help readers who would like to use pine to read his book.
Remarks
The 84th script for Blackcat1402 John F. Ehlers Week publication.
Readme
In real life, I am a prolific inventor. I have successfully applied for more than 60 international and regional patents in the past 12 years. But in the past two years or so, I have tried to transfer my creativity to the development of trading strategies. Tradingview is the ideal platform for me. I am selecting and contributing some of the hundreds of scripts to publish in Tradingview community. Welcome everyone to interact with me to discuss these interesting pine scripts.
The scripts posted are categorized into 5 levels according to my efforts or manhours put into these works.
Level 1 : interesting script snippets or distinctive improvement from classic indicators or strategy. Level 1 scripts can usually appear in more complex indicators as a function module or element.
Level 2 : composite indicator/strategy. By selecting or combining several independent or dependent functions or sub indicators in proper way, the composite script exhibits a resonance phenomenon which can filter out noise or fake trading signal to enhance trading confidence level.
Level 3 : comprehensive indicator/strategy. They are simple trading systems based on my strategies. They are commonly containing several or all of entry signal, close signal, stop loss, take profit, re-entry, risk management, and position sizing techniques. Even some interesting fundamental and mass psychological aspects are incorporated.
Level 4 : script snippets or functions that do not disclose source code. Interesting element that can reveal market laws and work as raw material for indicators and strategies. If you find Level 1~2 scripts are helpful, Level 4 is a private version that took me far more efforts to develop.
Level 5 : indicator/strategy that do not disclose source code. private version of Level 3 script with my accumulated script processing skills or a large number of custom functions. I had a private function library built in past two years. Level 5 scripts use many of them to achieve private trading strategy.
Release Note
b]OVERVIEWThe Ehlers Simple Decycler (ESD) indicator removes cyclical components from price data to reveal underlying trends, helping traders identify potential market movements and reversal points.
FEATURES
• Advanced cyclical filtering using Ehlers' methodology
• Dynamic upper and lower bands for trend confirmation
• Color-coded fill area for visual trend direction
• Built-in alert conditions for trading signals
• Customizable parameters for different market conditions
HOW TO USE
Select desired Price Source for analysis
Adjust High Pass Period to match market cycles
Monitor decycler line crossing between bands
Use color transitions to confirm trend direction
Set alerts for automated signal notifications
INTERPRETATION
• Decycler Line:
White line shows filtered price movement
Crossing above/below bands indicates potential reversals
• Bands:
Yellow band represents upper boundary
Fuchsia band marks lower boundary
Fill color changes with trend direction
ALERT CONDITIONS
• Upward Cross: Decycler crosses above previous value
• Downward Cross: Decycler crosses below previous value
PARAMETER GUIDELINES
• High Pass Period:
Lower values (20-50): Better for short-term trends
Higher values (50-100): Suitable for longer-term analysis
LIMITATIONS
• Performance varies with market volatility
• Best used alongside other technical indicators
• Results depend on proper parameter selection
Release Note
█ OVERVIEWThe Ehlers Simple Decycler V2 is a trend-following overlay indicator that strips slow cycles out of price to expose the underlying trend, based on John F. Ehlers' two-pole high-pass filter. V2 upgrades the classic decycler with trend-state tracking, gated long/short signals, a live dashboard, and optional ATR-based take-profit and stop-loss reference levels.
█ CONCEPTS
The decycler removes the slow spectral components of price with a two-pole high-pass filter (cutoff set by the High Pass Period) and subtracts them from price. What remains is a smooth line that follows the trend while ignoring sub-cycle wiggle.
Key principles:
• Decycler line — price minus its high-pass component: trend direction at a glance
• Symmetric bands — multiplier bands around the decycler frame the trend channel
• Slope-flip signals — the moment the decycler turns up/down marks a trend shift
• State machine + cooldown — repeated flips are suppressed to reduce whipsaw noise
█ HOW TO USE
1 — Add the indicator to your chart; it overlays price directly.
2 — Tune the High Pass Period: higher values smooth more and react slower; lower values react faster but flip more often.
3 — Read the slope: a rising green decycler favors longs, a falling red decycler favors shorts.
4 — Use band breaks of price as optional trend-strength context.
5 — Set alerts from the alert list (see SIGNALS) for hands-free monitoring.
Input Parameters
• Price Source — series fed into the filter (default: close)
• High Pass Period — cutoff period of the high-pass filter (default: 89)
• Band Multiplier — band width around the decycler (default: 1.05, i.e. ±5%)
• Enable Trend Signals — master switch for L/S labels, state machine and gated alerts
• Cooldown Bars — minimum bars between two signals (default: 3, 0 = off)
• Show Signal Labels / State Background / Dashboard — visual toggles
• Show TP/SL Levels — draws ATR-based TP/SL reference lines from the last signal (default: off)
• ATR Length / SL xATR / TP xATR — risk reference sizing (defaults: 14 / 2.0 / 3.0)
█ FEATURES
• Trend-colored decycler line: green (up), red (down), white (undefined)
• Long/short signal labels at slope flips with state gating and cooldown
• Background tint showing the active trend state
• Live dashboard: trend state, decycler value, slope, cooldown countdown, last signal
• Optional ATR-scaled take-profit / stop-loss reference lines
• Four alert conditions: raw crosses plus gated trend signals
█ SIGNALS
Visual Elements
• Green "L" label below a bar — decycler slope flipped up (bullish turn)
• Red "S" label above a bar — decycler slope flipped down (bearish turn)
• Green/red background — current trend state
• Teal/red line segments — TP/SL reference levels (when enabled)
Alerts
• Decycler Upward Cross / Downward Cross — raw slope flips (V1-compatible)
• Long Trend Signal / Short Trend Signal — gated by state machine and cooldown
█ LIMITATIONS
• Trend-following by design: expect whipsaws in flat, ranging markets
• Signals confirm on bar close; intrabar flips are not final
• Bands are multiplicative — on symbols trading near zero the band logic may distort
• TP/SL lines are reference levels only; this is an indicator, not a strategy
█ NOTES
• Based on John F. Ehlers' Simple Decycler ("Cycle Analytics for Traders")
• V2 of the original blackcat L2 script, rebuilt for Pine Script v6
• For educational purposes and not investment advice
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For questions or feedback, please use the comments section below.
Feel free to use and modify — attribution appreciated.
Don't miss out! The first and most important thing to do is to join my Discord chat now! Click here to start your adventure: discord.com/invite/ZTGpQJq My new github for more pine development soon: github.com/wxt-coder
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ข้อมูลและบทความไม่ได้มีวัตถุประสงค์เพื่อก่อให้เกิดกิจกรรมทางการเงิน, การลงทุน, การซื้อขาย, ข้อเสนอแนะ หรือคำแนะนำประเภทอื่น ๆ ที่ให้หรือรับรองโดย TradingView อ่านเพิ่มเติมใน ข้อกำหนดการใช้งาน
Don't miss out! The first and most important thing to do is to join my Discord chat now! Click here to start your adventure: discord.com/invite/ZTGpQJq My new github for more pine development soon: github.com/wxt-coder
คำจำกัดสิทธิ์ความรับผิดชอบ
ข้อมูลและบทความไม่ได้มีวัตถุประสงค์เพื่อก่อให้เกิดกิจกรรมทางการเงิน, การลงทุน, การซื้อขาย, ข้อเสนอแนะ หรือคำแนะนำประเภทอื่น ๆ ที่ให้หรือรับรองโดย TradingView อ่านเพิ่มเติมใน ข้อกำหนดการใช้งาน