Deadband Hysteresis Filter [BackQuant]

Deadband Hysteresis Filter [BackQuant]

What this is
This tool builds a “debounced” price baseline that ignores small fluctuations and only reacts when price meaningfully departs from its recent path. It uses a deadband to define how much deviation matters and a hysteresis scheme to avoid rapid flip-flops around the decision boundary. The baseline’s slope provides a simple trend cue, used to color candles and to trigger up and down alerts.

Why deadband and hysteresis help

• They filter micro noise so the baseline does not react to every tiny tick.
  
• They stabilize state changes. Hysteresis means the rule to start moving is stricter than the rule to keep holding, which reduces whipsaw.
  
• They produce a stepped, readable path that advances during sustained moves and stays flat during chop.
  

How it works (conceptual)
At each bar the script maintains a running baseline dbhf and compares it to the input price p.

• Compute a base threshold baseTau using the selected mode (ATR, Percent, Ticks, or Points).
  
• Build an enter band tauEnter = baseTau × Enter Mult and an exit band tauExit = baseTau × Exit Mult where typically Exit Mult < Enter Mult.
  
• Let diff = p − dbhf.
  If diff > +tauEnter, raise the baseline by response × (diff − tauEnter).
  If diff < −tauEnter, lower the baseline by response × (diff + tauEnter).
  Otherwise, hold the prior value.
  
• Trend state is derived from slope: dbhf > dbhf[1] → up trend, dbhf < dbhf[1] → down trend.
  

Inputs and what they control
Threshold mode

• ATR — baseTau = ATR(atrLen) × atrMult. Adapts to volatility. Useful when regimes change.
  
• Percent — baseTau = |price| × pctThresh%. Scale-free across symbols of different prices.
  
• Ticks — baseTau = syminfo.mintick × tickThresh. Good for futures where tick size matters.
  
• Points — baseTau = ptsThresh. Fixed distance in price units.
  

Band multipliers and response

• Enter Mult — outer band. Price must travel at least this far from the baseline before an update occurs. Larger values reject more noise but increase lag.
  
• Exit Mult — inner band for hysteresis. Keep this smaller than Enter Mult to create a hold zone that resists small re-entries.
  
• Response — step size when outside the enter band. Higher response tracks faster; lower response is smoother.
  

UI settings

• Show Filtered Price — plots the baseline on price.
  
• Paint candles — colors bars by the filtered slope using your long/short colors.
  

How it can be used

• Trend qualifier — take entries only in the direction of the baseline slope and skip trades against it.
  
• Debounced crossovers — use the baseline as a stabilized surrogate for price in moving-average or channel crossover rules.
  
• Trailing logic — trail stops a small distance beyond the baseline so small pullbacks do not eject the trade.
  
• Session aware filtering — widen Enter Mult or switch to ATR mode for volatile sessions; tighten in quiet sessions.
  

Parameter interactions and tuning

• Enter Mult vs Response — both govern sensitivity. If you see too many flips, increase Enter Mult or reduce Response. If turns feel late, do the opposite.
  
• Exit Mult — widening the gap between Enter and Exit expands the hold zone and reduces oscillation around the threshold.
  
• Mode choice — ATR adapts automatically; Percent keeps behavior consistent across instruments; Ticks or Points are useful when you think in fixed increments.
  
• Timeframe coupling — on higher timeframes you can often lower Enter Mult or raise Response because raw noise is already reduced.
  

Concrete starter recipes

• General purpose — ATR mode, atrLen=14, atrMult=1.0–1.5, Enter=1.0, Exit=0.5, Response=0.20. Balanced noise rejection and lag.
  
• Choppy range filter — ATR mode, increase atrMult to 2.0, keep Response≈0.15. Stronger suppression of micro-moves.
  
• Fast intraday — Percent mode, pctThresh=0.1–0.3, Enter=1.0, Exit=0.4–0.6, Response=0.30–0.40. Quicker turns for scalping.
  
• Futures ticks — Ticks mode, set tickThresh to a few spreads beyond typical noise; start with Enter=1.0, Exit=0.5, Response=0.25.
  

Strengths

• Clear, explainable logic with an explicit noise budget.
  
• Multiple threshold modes so the same tool fits equities, futures, and crypto.
  
• Built-in hysteresis that reduces flip-flop near the boundary.
  
• Slope-based coloring and alerts that make state changes obvious in real time.
  

Limitations and notes

• All filters add lag. Larger thresholds and smaller response trade faster reaction for fewer false turns.
  
• Fixed Points or Ticks can under- or over-filter when volatility regime shifts. ATR adapts, but will also expand bands during spikes.
  
• On extremely choppy symbols, even a well tuned band will step frequently. Widen Enter Mult or reduce Response if needed.
  
• This is a chart study. It does not include commissions, slippage, funding, or gap risks.
  

Alerts

• DBHF Up Slope — baseline turns from down to up on the latest bar.
  
• DBHF Down Slope — baseline turns from up to down on the latest bar.
  

Implementation details worth knowing

• Initialization sets the baseline to the first observed price to avoid a cold-start jump.
  
• Slope is evaluated bar-to-bar. The up and down alerts check for a change of slope rather than raw price crossings.
  
• Candle colors and the baseline plot share the same long/short palette with transparency applied to the line.
  

Practical workflow

• Pick a mode that matches how you think about distance. ATR for volatility aware, Percent for scale-free, Ticks or Points for fixed increments.
  
• Tune Enter Mult until the number of flips feels appropriate for your timeframe.
  
• Set Exit Mult clearly below Enter Mult to create a real hold zone.
  
• Adjust Response last to control “how fast” the baseline chases price once it decides to move.
  

Final thoughts
Deadband plus hysteresis gives you a principled way to “only care when it matters.” With a sensible threshold and response, the filter yields a stable, low-chop trend cue you can use directly for bias or plug into your own entries, exits, and risk rules.