Unlock new application areas and explore enhanced possibilities for existing products with reliable proximity sensing and distance ranging capabilities, effective over short and longer distances.

Channel Sounding is the key feature of Bluetooth 6.0 specification for Bluetooth Low Energy. It enables accurate and secure distance measuring with built-in security features and seamless interoperability. The upcoming nRF54 Series will support channel sounding.

Nordic Distance Toolbox (NDT) is an alternative proprietary ranging solution from Nordic based on well proven measurement methods. The nRF52 and nRF53 Series support NDT.

This new Bluetooth feature utilizes various ranging techniques and security measures to enable secure and accurate distance measurement between two devices without increasing product complexity or size. Channel Sounding accuracy meets the requirements for applications such as smart door locks, home appliances, personal item tracking tags, or the presence detection of high-value assets in industrial and professional settings.

• The Bluetooth specification defines new features of the radio (PHY), features of the controller, security measures, and measurement procedures needed to collect raw data
• The conversion of raw data into the resulting distance using dedicated algorithms is performed at the application level and is outside the scope of the Bluetooth specification
• A typical channel sounding setup consists of an Initiator and a Reflector, where the Initiator performs the calculations, and the Reflector can be a very simple ultra-low-power device, such as a location tag
• The configuration of the measurements and the algorithms can be adjusted to balance the required accuracy, latency, security, and power consumption
• Before the measurement, devices need to pair and establish an encrypted LE-ACL connection
• Several ranging-specific mechanisms, including randomization, defense against symbol manipulation, and attack detection provide the security of the measurement itself
• Phase-based ranging (PBR) and round-trip time (RTT) are the two possible measurement methods, which can be used independently or combined for finer ranging or coarser ranging over longer distances
• PBR and RTT measurements can be cross-checked against each other to increase the confidence level of the measurement
• Basic hardware setups can use a single antenna, maintaining a design identical to standard Bluetooth Low Energy devices for simple and compact products
• Advanced hardware setups with multiple antennas are possible for products with requirements for higher accuracy and robustness
• Compared to other ranging solutions, Channel Sounding is standardized and included in the Bluetooth qualification program
• The adoption of Channel Sounding in mobile phones and a broad range of Bluetooth devices will enable many possibilities for new use cases with Bluetooth products from different vendors
• Low-power consumption is assured by using Bluetooth Low Energy radio, as the Channel Sounding procedure consumes the same amount of power as regular data transfer

The Bluetooth 6.0 specification defines Channel Sounding up to the point where the raw data is collected by the Initiator. As the industry advances, there is a significant focus on developing algorithms to convert this raw data into final results. While this technology can be implemented on any Bluetooth 6.0 device, mobile phones are expected to primarily boost the adoption of Channel Sounding. Phones are set to manage the algorithmic tasks, enabling the development of simple and interoperable products that perform seamlessly in the Reflector role. Support for Channel Sounding in Android and iOS is highly anticipated.

The forthcoming nRF54 Series will feature support for Channel Sounding. Be on the lookout for our new products, the nRF54H20 and the nRF54L15 from the nRF54H and nRF54L Series, respectively.

Nordic Distance Toolbox is a  proprietary solution from Nordic, serving as an alternative to Channel Sounding. It offers advanced distance measurements and proximity sensing capabilities, utilizing Phase-Based Ranging (PBR) and Round-Trip Time (RTT) methods. The accompanying software library includes an algorithm that accurately determines the distance between two NDT-enabled devices, significantly enhancing accuracy compared to solutions based solely on Received Signal Strength Indicator (RSSI). This improved accuracy enables the implementation of applications that were previously unfeasible with RSSI alone, opening up new possibilities in various sectors. NDT is supported on selected SoCs from the nRF52 and nRF53 Series, making it a versatile tool for developers.

The Sample in nRF Connect SDK demonstrates the functionality of Nordic Distance Toolbox: Bluetooth: nRF Distance Measurement with Bluetooth LE discovery

Short introduction video

In-depth webinar