Biosignals Studio (Desktop) offers a Signal Processing Toolbar in post-processing mode that provides you with quick access to the most commonly used filters.
Here you’ll find simple filters like Invert Signal, Signal Smoothing, Peak / Valley finder, basic frequency filters, and more.
In this article, you’ll learn how to get the most out of the signal processing toolbar.
Paid Feature
This feature is available on all Biosignals Studio (Desktop) Academic & Commercial licenses.
Processing Context
The Signal Processing Toolbar is the first stage of the Biosignals Studio Signal Processing Pipeline and operates in the following context:
- The input data consists of sensor signals, either raw or already pre-processed by the sensor hardware.
- Toolbar filters are applied globally to the entire signal.
- Toolbar filters are only applied to the selected signals
- The processed output signals generated by the Toolbar serve as input for the Signal Processing Toolbox and other Processing Modules later in the pipeline.
Available Filters
The toolbar contains the filters listed below. Some filters have additional signal settings accessible via the ‘v‘ icon next to the filter.
| Filter | Settings |
|---|---|
| Invert Signal Flips the signal vertically by multiplying all values by -1 | — |
| Signal Smoothing Reduces short-term fluctuations using a moving average window | Window Size (20 to 100 ms) Larger windows produce smoother signals but may remove fast details; smaller windows preserve more detail but smooth less noise. |
| Rectify Signal Converts all negative values into positive values | — |
| Binary Onset Detects when the signal crosses a threshold and converts it into binary activation states | Threshold Higher thresholds detect only stronger activations; lower thresholds detect weaker activations but may increase noise sensitivity. New Value Defines the value assigned when the signal is over the threshold. |
| Low-Pass Filter Removes high-frequency components while preserving slower signal variations | Cut-Off Frequency (> 0 Hz) Lower cut-off frequencies remove more high-frequency content; higher values preserve more detail. Filter Order (positive integers) Higher filter orders create sharper filtering but may introduce more delay or distortion. |
| High-Pass Filter Removes low-frequency drift and baseline movement while preserving faster changes | Cut-Off Frequency (> 0 Hz) Higher cut-off frequencies remove more low-frequency content; lower values preserve more baseline information. Filter Order (positive integers) Higher filter orders create sharper filtering but may introduce more delay or distortion. |
| Notch Filter Removes a narrow frequency band, typically used to suppress electrical interference | Cut-Off Frequency (> 0 Hz) Defines the frequency to suppress. Quality Factor (Q) (positive integer) Higher Q removes a narrower frequency band; lower Q removes a wider band around the target frequency. |
| Powerline Filters Suppresses 50 Hz or 60 Hz powerline noise | Frequency Selection Select 50 Hz or 60 Hz depending on the local electrical grid frequency. |
| Peak Detection Identifies local maxima | Minimum Peak Amplitude Higher thresholds ignore smaller peaks; lower thresholds detect more peaks, including noise. Minimum Interval Between Peaks Larger intervals reduce repeated detections of the same event; smaller intervals allow closely spaced peaks. |
| Valley Detection Identifies local minima | Minimum Valley Amplitude Higher thresholds ignore smaller valleys; lower thresholds detect more valleys, including noise. Minimum Interval Between Valleys Larger intervals reduce repeated detections of the same event; smaller intervals allow closely spaced valleys. |
| Signal Amplification Increases the signal amplitude by applying a gain factor | Amplification Factor Values greater than 1 amplify the signal; values between 0 and 1 attenuate it. |
💡 Tip:
You can find helpful reminders on this information by hovering over the different filters and info icons of the signal processing toolbar. 👇
Selecting Your Input Signals
The input signals for the signal processing toolbar are selected from the signal drop-down list in the top-right corner of the toolbar.
For sensors with a single signal, toolbar filters are automatically applied to that signal.
For signal bundles with multiple signals (such as accelerometers with separate X, Y, and Z axes), you can:
- Disable Link Channels to manually select which signals should be processed from the dropdown menu
- Enable Link Channels to apply filters to all signals simultaneously
Selecting & Apply Filters
You can select multiple filters and specify their application order by clicking each filter in the desired order. The order number of the filter is visualized as a small blue counter on the filter icon.
Here’s an example of a toolbar processing chain that applies an Invert Signal, Signal Smoothing and a 50 Hz Powerline Filter in this order.
To remove an individual filter, click the filter icon again. To remove all, click the Clear Filter option.
To apply the selected filters, press the Process button.
Note that changes to the selected filter order are not automatically reprocessed. Click the Process button again whenever you’ve made changes to the selected filters.
