Bluetooth 6.0 introduced Channel Sounding, a ranging method that replaces RSSI guesswork with phase-based BLE ranging to under a metre.
The Bluetooth SIG formally defined BLE 6 Channel Sounding in Core Specification 6.0, positioning Bluetooth as a viable technology for indoor proximity authentication and high-accuracy asset tracking. What the specification cannot supply is the engineering depth required to ship it.
That is why this list is short. Channel Sounding, specifically Phase-Based Ranging (PBR), requires firmware teams that understand multi-tone phase measurement, integer ambiguity resolution, RF antenna layout, and CS security architecture. A firm that has shipped BLE stacks for fitness trackers may not have touched any of these. The Bluetooth 6.0 specification arrived in late 2024. First-generation CS-capable chipsets entered volume production the same year. The window for any company to accumulate a real production track record has been narrow.
This article reviews ten companies—chipset vendors, module makers, and embedded development firms—best positioned to build Channel Sounding into a deployable product. It explains what differentiates them, how to score a shortlisted partner, and what questions to ask before committing to a development engagement.
Two distinct categories run through this list. Chipset vendors (Nordic, Silicon Labs, NXP) supply the silicon and reference SDK implementations that every CS project depends on. Development firms (needCode, Promwad, ByteSnap) translate those reference designs into certified, use-case-specific production firmware. Knowing which type you are evaluating prevents misaligned expectations.
What separates a qualified BLE CS partner from a competent BLE firmware firm
Not all BLE expertise transfers to Channel Sounding. The criteria below distinguish firms that can build a production CS system from those that have run a chip vendor’s demo.
PBR implementation, not just RTT or IBT. Round-Trip Time (also referred to as Initiator-Based Timing or IBT) is simpler to implement and typically demonstrated first. Phase-Based Ranging is the method that achieves sub-30 cm accuracy. Ask explicitly whether a firm has PBR in production code or reference code, and at what tone count.
Integer ambiguity resolution. Phase wraps at approximately 12.5 cm intervals at 2.4 GHz. A PBR engine that cannot resolve this ambiguity cannot report accurate absolute distances beyond short ranges. Ask for the firm’s resolution algorithm and its validated performance at distances beyond 1 metre.
Antenna design capability. CS phase measurement is sensitive to antenna coupling, PCB parasitic capacitance, and TX/RX path isolation. Software-only firms without RF hardware competency will hit a ceiling here and need an external hardware partner.
Bluetooth SIG engagement. Firms that contributed to specification development, ran interoperability tests, or participated in CS qualification programs understand edge cases that are not visible in the published specification text.
Security architecture awareness. CS defines four authentication levels. Digital key and access control applications require level 3 or 4, which binds ranging to an encrypted connection and mitigates relay attacks. Ask which authentication level a firm has implemented and whether they have tested against relay scenarios.
Mobile platform integration. Google’s Android Channel Sounding API, available from Android 15, defines host-side procedure parameters that any phone-as-key or consumer CS application must comply with. Ensure your development partner understands these constraints when targeting Android endpoints.
Accuracy validation tooling. Ask whether the firm validates BLE ranging accuracy using a calibrated channel sounder or reference fixture, and whether they can provide measured accuracy data at distances beyond 1 metre, not just in-lab demos.
Partner scoring checklist
Use this table when evaluating shortlisted vendors. Score each criterion independently, then total the points. A firm with a combined score under 8 out of 14 carries meaningful production risk for a CS-specific engagement.
Criterion 0: absent 1: partial 2: demonstrated
CS chipset experience (nRF54H20 or EFR32xG24 in active use) No BLE CS chipset work SDK evaluation or lab prototype Working CS firmware shipped on target hardware PBR implementation (not IBT/RTT only) RTT-only demonstration PBR prototype, single tone Multi-tone PBR engine with validated accuracy data Integer ambiguity resolution Not addressed Aware of the problem Proprietary algorithm, validated across multiple distances Antenna and RF design capability Software delivery only PCB design via external subcontractor In-house RF layout and antenna characterisation Bluetooth SIG engagement No documented engagement Bluetooth SIG member Spec contribution, interop testing, or CS qualification CS security implementation RSSI-replacement mindset CS auth level 1–2 Auth level 3–4 with relay-attack mitigation Production certification track record Proof of concept only Single-market certification delivered CE + FCC + market certification on BLE products
The 10 BLE Channel Sounding development companies
1. needCode, Kraków, Poland | Embedded BLE development consultancy
needCode’s Channel Sounding work is built on a foundation few development firms can claim: the team contributed directly to BLE Mesh specification development and test plans at the Bluetooth SIG. Engineers hold backgrounds from Nordic Semiconductor, Qorvo, Texas Instruments, Silicon Labs, and Espressif, meaning their understanding of the CS specification extends to the engineering intent behind each design choice, not just the surface behaviour.
On hardware, needCode works with Nordic’s nRF54H20 and nRF5340 series. Their PBR engine implements multi-tone phase measurement with integer ambiguity resolution, the step that most Channel Sounding demonstrations omit. The outcome is accurate absolute distance reporting across ranges, not just phase deltas that are only meaningful within the first few centimetres.
Their Trusted Proximity protocol layers cryptographic authentication on top of PBR ranging so that a single CS procedure simultaneously measures distance and verifies device identity. In access control applications, an attacker could otherwise relay a legitimate device’s Bluetooth signal past a physical barrier to spoof proximity; the Trusted Proximity protocol is designed to defeat this class of attack. Dynamic threshold management defines Green, Yellow, and Red proximity zones with real-time alert output at sub-millisecond reaction times, a requirement in industrial safety and hazardous-environment geofencing deployments.
Alongside Channel Sounding, needCode implements PAwR (Periodic Advertising with Responders), enabling CS-ranging tags to receive configuration updates and transmit results on a shared broadcast schedule. This approach supports large-scale tag deployments without the connection establishment overhead that drives power consumption in per-tag BLE links.
needCode holds ISO 9001 and ISO 27001 certification from their Kraków facility and operates as a Qorvo Official Partner with over five years of joint development history. Published work includes a BLE badge for peer-to-peer proximity data sharing, the Butterfly.care infant vital signs wearable, and an e-book on worker safety and geofencing in hazardous environments.
Checklist score guidance: A team with this combination of Bluetooth SIG specification contribution, production PBR code, integer ambiguity resolution, and CS security architecture consistently reaches the upper range of the scoring criteria above.
2. Nordic Semiconductor, Trondheim, Norway | Chipset vendor
Nordic’s nRF54H20 was among the first production SoCs to ship with Bluetooth Core 6.0 features, including Channel Sounding. The 4th-generation multiprotocol radio achieves −99 dBm RX sensitivity at 1 Mbps BLE, and the SoC integrates multiple Arm Cortex-M33 processors alongside hardware cryptographic acceleration for PSA Certified Level 3 security.
The nRF Connect SDK includes CS initiator and reflector sample applications maintained by Nordic’s engineering team. These reference implementations form the baseline that Nordic ecosystem development partners build from. The nRF54L15 targets ultra-low-power CS applications where battery or energy-harvesting constraints are primary.
Nordic is a chipset vendor, not a development services firm. Choosing Nordic means choosing the silicon and SDK ecosystem. Custom CS firmware and product-specific implementation require a qualified development partner.
3. Silicon Labs, Austin, Texas | Chipset vendor
Silicon Labs’ EFR32xG24 supports Channel Sounding with up to four antenna paths between initiator and reflector. Silicon Labs’ Channel Sounding documentation reports PBR accuracy of ±0.3 m at ranges under 5 metres and ±0.5 m beyond 5 metres. These figures reflect the reference chipset’s measured performance with the CS development kit antenna configuration.
Their Channel Sounding Pro Kit (xG24-PK6036A) ships two mainboards and two radio boards (both initiator and reflector hardware in a single kit), which accelerates early-stage accuracy experiments. Simplicity Studio 6 includes CS sample applications and a protocol analyser for logging CS procedure steps.
Silicon Labs explicitly distinguishes PBR from RTT in their SDK and documentation, making it easier for development teams to select the appropriate ranging method. Like Nordic, Silicon Labs is a chipset vendor; production firmware on EFR32xG24 requires a development partner.
4. NXP Semiconductors, Eindhoven, Netherlands | Chipset vendor
NXP’s KW47 series BLE SoC supports Bluetooth 6.0 including Channel Sounding, extending NXP’s reach into high-accuracy ranging for automotive, industrial, and smart home markets. NXP’s EdgeLock security subsystem, established across their wireless and MCU portfolio, brings hardware-root-of-trust capabilities relevant to CS deployments that require security authentication levels 3 and 4.
NXP’s IoT partner ecosystem is extensive, with certified reference designs across automotive access, industrial asset tracking, and smart building control. For development teams already using NXP silicon for other system functions, adding CS on the KW47 avoids a chipset change mid-design, which is a real schedule advantage in hardware-constrained projects.
NXP does not provide development services for custom BLE firmware. External firmware partners are required for production CS implementation on KW47.
5. u-blox, Thalwil, Switzerland | Module maker
u-blox builds BLE modules for industrial, automotive, and IoT applications where pre-certified radio hardware is needed faster than a custom PCB allows. Their ANNA-B4 module is based on Nordic nRF5340 and targets applications that need a compact, pre-certified BLE radio.
CS support on the ANNA-B4 follows the nRF5340 SDK CS maturity timeline. As Nordic’s CS implementation matures through 2025–2026, module-based CS designs on ANNA-B4 become increasingly viable. u-blox manages radio certification across global markets, allowing development teams to focus on CS firmware rather than antenna compliance.
For projects where time-to-market is constrained and in-house antenna design is not available, u-blox modules lower the hardware risk in a CS engagement.
6. Ezurio (formerly Laird Connectivity), Dublin, Ireland | Module and firmware vendor
Ezurio’s BL5340 module is based on Nordic nRF5340 and targets industrial and commercial IoT applications requiring extended operating temperature ranges and pre-certified radio hardware. Their SmartBASIC scripting environment allows AT command–style firmware customisation without deep embedded C development, which reduces integration effort for host MCU–driven architectures.
Ezurio carries FCC, CE, and ISED certifications across their module portfolio. For CS projects where the host application runs on a separate processor communicating with the BLE module over UART, Ezurio’s approach significantly reduces the RF compliance burden.
CS-specific firmware depth at the SmartBASIC level has limits. For projects requiring a custom PBR engine, integer ambiguity resolution, or security authentication levels 3–4, a dedicated firmware house alongside the Ezurio module is the practical combination.
7. Atmosic Technologies, San Jose, California | Chipset vendor (ultra-low-power)
Atmosic’s ATM-series BLE chipsets are built for energy harvesting, operating from RF energy, ambient light, or motion without a battery. Their ATM34 SoC adds Channel Sounding capabilities to this architecture, making it relevant for passive asset tags or wearables where battery replacement over a multi-year deployment is not operationally viable.
The engineering challenge Atmosic addresses is completing a CS ranging procedure within the energy budget available from a harvesting source. Standard BLE CS implementations assume a battery; Atmosic’s SDK provides explicit power-budget tooling for harvest-constrained devices. This is a narrow but genuine differentiation for high-volume, battery-free CS tag applications.
Atmosic is a chipset vendor. Custom CS firmware on their platform requires an external development partner familiar with energy-harvesting power constraints.
8. Promwad, Warsaw, Poland / Vilnius, Lithuania | Embedded development firm
Promwad offers hardware and firmware development for IoT, medical, and industrial clients, with documented experience across Nordic and Silicon Labs BLE platforms. Their service coverage includes PCB design, RF layout, BLE stack integration, and certifications consulting.
For a CS engagement, Promwad’s value is the combination of hardware engineering (antenna layout and RF characterisation) alongside firmware integration, avoiding the coordination overhead that arises when PCB design and firmware come from separate vendors. CS-specific PBR engine work is in early adoption phase at Promwad, consistent with the overall market timeline.
9. ByteSnap Design, Birmingham, UK | Embedded development consultancy
ByteSnap brings BLE and wireless IoT engineering to consumer, medical, and industrial applications. The team has delivered CE- and FCC-certified BLE products across multiple Nordic and Silicon Labs chipset generations and operates a certifications practice alongside hardware and firmware development.
CS-specific production experience at ByteSnap is developing in 2025–2026 alongside the first commercial CS chipset releases. For projects based in the UK or requiring regulatory expertise across EU and North American markets, ByteSnap represents a technically capable option for scoping.
10. Silvair, Warsaw, Poland | BLE Mesh infrastructure vendor
Silvair contributed to the Bluetooth Mesh specification at the Bluetooth SIG, placing them among the few companies worldwide with direct Bluetooth spec authorship experience. Their commercial focus is BLE Mesh infrastructure for smart buildings and commercial lighting, not general-purpose firmware development services.
Their relevance to Channel Sounding is specific: proximity awareness applications enabled by CS (zone-based access control, lighting adjustment by approach distance) sit within Silvair’s existing Mesh deployment model. CS proximity events can trigger Mesh-controlled infrastructure responses without separate middleware layers, and Silvair’s platform is positioned to accept those events.
Silvair is an infrastructure product vendor, not a contract development firm. For custom CS firmware, Silvair is not the right engagement. For projects where CS proximity events need to trigger BLE Mesh–controlled infrastructure, they are worth a conversation.
How to use this shortlist
The scoring checklist gives a structured starting point, but a few project-specific factors often matter more than the total score.
If the product needs phone-as-key functionality, chipset vendor support and Android CS stack maturity drive chipset selection before firmware partner selection. If the application is industrial safety, such as geofencing in a factory or hazardous site, security authentication level and zone threshold management are the differentiating criteria. Raw accuracy figures matter less than reliable behaviour when a person approaches a boundary at an angle, or when a forklift moves between two ranging devices.
The practical sequencing for most teams: confirm chipset based on target application and power budget → select a development firm whose CS firmware experience is on that chipset → run a scoped PBR prototype before committing to full product firmware. Switching chipsets mid-project because a preferred firmware house only knows EFR32xG24 when the design targets nRF54H20 is an avoidable delay worth addressing in the first scoping call.
needCode builds BLE Channel Sounding firmware for hardware OEMs, consumer ranging products, and industrial proximity systems, including PBR engines with integer ambiguity resolution and CS security at authentication levels 3 and 4. If you are evaluating BLE ranging development partners and want to discuss chipset selection, accuracy targets, and security architecture before committing to a development engagement, we are happy to talk. Book a free discovery call or get in touch. or get in touch.](https://needcode.io/calendly)
Frequently asked questions
BLE Channel Sounding is a distance measurement capability introduced in Bluetooth Core Specification 6.0, published by the Bluetooth SIG in late 2024. It replaces RSSI-based proximity estimation with Phase-Based Ranging (PBR) or Round-Trip Time measurements across up to 72 radio channels, achieving sub-metre accuracy under line-of-sight conditions.
PBR on current CS chipsets achieves ±0.3–0.5 m under line-of-sight conditions. UWB typically achieves 10–30 cm with TDoA and 5–10 cm with DS-TWR. BLE CS trades some ranging accuracy for lower BOM cost, elimination of a second radio, and compatibility with existing Bluetooth infrastructure. For applications where 30–50 cm accuracy is sufficient, BLE CS avoids the anchor infrastructure cost of UWB RTLS.
PBR measures the phase of received RF tones. Phase repeats every wavelength (approximately 12.5 cm at 2.4 GHz). A single-tone measurement cannot distinguish a device at 12.5 cm from one at 25 cm or 37.5 cm. Multi-tone processing across multiple channels resolves this ambiguity and recovers absolute distance. A CS implementation without integer ambiguity resolution produces accurate results only within a few centimetres and degrades unpredictably beyond that.
Nordic Semiconductor nRF54H20 and nRF54L15, Silicon Labs EFR32xG24, NXP KW47, and Qualcomm’s BT 6.0 SoC all support Channel Sounding. Nordic and Silicon Labs are furthest ahead in SDK sample code and developer documentation as of mid-2025.
PBR (Phase-Based Ranging) measures phase rotation across multiple tones to estimate distance; it is more accurate but requires multi-tone processing and integer ambiguity resolution. IBT (Initiator-Based Timing) measures signal round-trip time; it is simpler to implement but typically achieves 0.5–1 m accuracy rather than sub-30 cm. Most production CS systems use PBR, sometimes with IBT as a fallback.
