RSSI Viewer

This summer, we offered several internships in our Krakow office, where students could work on various projects. One of these projects was the RSSI viewer developed by Piotr Czerwiec, a set of programs to visualize 2.4 GHz band usage. The RSSI viewer scans this band, records signal level on particular frequencies, and presents combined results in several ways. The tool can be used to look for interferers and to check how channels are utilized. I hope you find the tool useful! Comments and suggestions for improvements are welcome in the comments section.

PC application

There are several ways to visualize data:

  • 2D spectrum graph, showing actual RSSI, averaged, and max
  • 3D spectrum graph, showing band usage over time
  • Persistence view, showing the frequency of specific RSSI levels over channels
  • Advertising channels view, showing only energy on selected channels over time

The picture below shows the PC application window.

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The application is written in Java and supports Windows, Mac, and Linux.

Android app

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In addition to the PC application, there is also an app for Android. „nRF RSSI Analyser.apk” can collect and present RSSI data, which is helpful when you want to be more mobile and do some tests in the field.

Front end

As a front end, you can use PCA10001 or the nRF51 USB dongle. There is a special application, RSSI measurer (rssi_measurer.hex), which scans the band and transmits data over USB to the computer. In parallel, it advertises over Bluetooth Low Energy with the name „Nordic_RSSI”. Like this, data can be gathered remotely. This is achieved thanks to a new feature of the S110 SoftDevice v7.0.0 that allows radio slots reservation.

To allow BLE communication and RSSI measurements, the file s110_nrf51822_v7.0.0_softdevice.hex (available from must be flashed on the nRF51 chip using nRFgo Studio, for example.

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The front-end device scans the band by channels, therefore it does not track signal levels continuously on the entire band channel. This means that some transmissions could remain unnoticed.

The Android and Mac OS applications are in alpha stage. They can be used to demonstrate what is possible to achieve with the applications, but they should not be used for actual tests.


nRF51 firmware

PC Application for Windows

Linux/Mac Os Application

Android Application