> For the complete documentation index, see [llms.txt](https://www.multi-module.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.multi-module.org/using-the-module/spectrum-analyzer.md).

# Spectrum Analyzer

A radio running EdgeTX or OpenTX 2.3.0 or higher can use an internal or external MULTI-Module as a 2.4GHz spectrum analyzer.

The spectrum analyzer will show the strength of signals in the 2.4GHz band.

![2.4GHz Spectrum Analyzer](/files/-MGYcaGktfOUxhTtnthw)

### Using the Spectrum Analyzer

1. Long-press the **SYS** button to access the **TOOLS** menu
2. Scroll down and highlight  the appropriate **Spectrum** option in the menu
   1. Choose **Spectrum (INT)** for radios with an internal MULTI-module
   2. Choose **Spectrum (EXT)** for radios with an external MULTI-Module
3. Press **ENT** to start the Spectrum Analyzer

![Spectrum Analyzer in the TOOLS Menu](/files/-MGYcgClUJIv8kwPs22S)

{% hint style="success" %}
**Spectrum (EXT)** only appears in the menu if a model which uses the external MULTI-Module is selected.
{% endhint %}

{% hint style="warning" %}
A bug in OpenTX 2.3.9 and earlier prevents the spectrum analyzer from starting when a recently-added MULTI-Module protocol (e.g. FrSkyX2) is configured in the currently-selected model.

As a workaround, select a model which uses an older protocol (e.g. DSM, FrSky, or Flysky) before starting the spectrum analyzer.
{% endhint %}

### Spectrum Analyzer Display

![Spectrum Analyzer Display](/files/-MGYcaGktfOUxhTtnthw)

The display shows frequencies on the 2.4GHz spectrum, from 2400MHz to 2480MHz. The X (horizontal) axis shows the frequency in MHz and the Y (vertical) axis shows relative signal strength.

**F:** Frequency at the center of the plot (fixed at 2440MHz)\
**S:** Bandwidth of the plot (fixed at 80MHz)\
**T:** Position of the cursor (vertical line)

Pressing **ENT** and scrolling left and right allows the **T** value to be changed, which will move the vertical line to highlight a specific frequency.

{% hint style="info" %}
In a future firmware release the **F** and **S** values will be adjustable, allowing the analyzer to be focused on a particular part of the spectrum.
{% endhint %}