---
title: Gaussian Filter
slug: litmusedge/gaussian-filter
docTags: 
createdAt: 2024-08-06T19:29:37.814Z
---

The Gaussian Filter processor smooths a signal using a Gaussian (bell-curve) weighting function.

## Why use Gaussian Filter

Use this processor to reduce noise in a signal while preserving its underlying trend, for example, smoothing a noisy sensor reading before it reaches a dashboard or a downstream calculation.

## How it works

The processor calculates the mean and standard deviation of the current window of values, then uses them to weight the current value: values closer to the window's mean carry more weight, and values farther from it carry less.

Specifically, it calculates a coefficient as `1 / (sqrt(2π) × standard deviation)` and an exponential term as `exp(-1/2 × (current - mean)² / standard deviation²)`. Multiplying the coefficient by the exponential term gives the filtered value.

If your input tag doesn't publish at a steady rate, use **Timer Interval** to publish a value on a fixed schedule instead of waiting for the next incoming event. If your input already publishes at the interval you expect, enter `0` to disable the timer.

## Parameters

| **Parameter**      | **Details**                                                                                                                              |
| ------------------ | ---------------------------------------------------------------------------------------------------------------------------------------- |
| Window Size        | The window (in seconds) over which the Gaussian filter calculates the mean and standard deviation.                                       |
| Timer Interval     | Sets a timer (in milliseconds) that continuously publishes the output when no event triggers the filter. Enter `0` to disable the timer. |
| Pass Through Value | Determines whether the processor's output is the filtered value or the original unchanged input value.                                   |

## Related topics

-  [Use the Gaussian Filter Function](docId\:XbbaG37w-XRnNn7t9X6Zq)