Bluetooth channel sounding: a distance arrow without UWB
Bluetooth channel sounding is the feature that could eventually give an ordinary cheap tag the thing only expensive tags have: a real distance to the object, rather than a guess from how loud its signal is. On 4 August 2026 it took a meaningful step towards that, when Silicon Labs announced a chip built for coin-cell life that carries the full ranging feature set. Our stance, plainly: this is genuinely important, it is not vapourware, and it will not help anybody buying a tag this year. Here is why all three of those are true at once.
What channel sounding actually is
Every ordinary Bluetooth device infers distance the crude way, from received signal strength, which is a terrible ruler — a body, a wall or a turned tag shifts the reading as much as several metres of real movement would.
Channel sounding does something different. Two radios exchange signals across multiple frequencies and measure the phase relationship between them, combined with round-trip timing, to calculate how far apart they are. It is the standards world's answer to the problem Ultra Wideband has been solving in premium hardware, built into the Bluetooth specification rather than requiring a second radio.
The Bluetooth SIG introduced it in Core Specification 6.0, adopted on 3 September 2024. Core Specification 6.2, released on 4 November 2025, hardened it further by adding an amplitude-based metric for detecting attacks that try to spoof a measured distance — a change aimed squarely at car keys and door locks, where a falsified distance opens something.
Why 4 August 2026 mattered
Silicon Labs announced the BG2B that day: an Arm Cortex-M33 Bluetooth 6 Low Energy system-on-chip which the company describes as its lowest-power Bluetooth LE part to date, quoting 1.1 µA sleep current with RAM retention and 14 to 15% lower active current than its predecessors.
Two details in that announcement are the reason it is worth writing about. First, the power figures put channel sounding within reach of a device that runs for years on a single coin cell, which previous ranging silicon did not. As CNX Software noted in its coverage the same day, this is a part built for battery life rather than for mains-powered gateways.
Second, Silicon Labs states the chip is designed to meet Apple's and Google's channel sounding specifications. That is the sentence that matters most, because a ranging feature is useless unless the phone in your pocket implements the same thing. Both platform owners having published specifications for it is a stronger signal about where this goes than any chip launch on its own.
Why your tag will never get it
This is where enthusiasm has to meet the hardware. Channel sounding is implemented in silicon at both ends of the link. It cannot be added by a firmware update, an app update or an iOS release, because the radio in an existing tag simply does not have the circuitry to do it.
So the upgrade path is: new chips, then new tag designs using them, then those tags reaching shops, then phones exposing the capability to apps. Each of those steps takes months and the last one is not in the tag maker's hands at all. Anybody telling you a tag on sale now is "channel sounding ready" is describing a marketing position, not a capability.
There is also a cost question that nobody in the industry likes discussing. Finding tags sell for a few pounds and use mature, cheap silicon precisely because of it. A part announced this year, aimed initially at secure vehicle entry and industrial asset tracking, is not going into a two-pack of key ring tags any time soon.
Is it worth waiting for?
No, and we would say that even if it cost us the sale of a tag today.
The honest position is that the arrow solves a specific, narrow problem: the last three metres, outdoors or in a large open space, where a map is too coarse and a sound is too directionless. Indoors, in a house, a buzzer at close range does the same job well enough that most people would not notice the difference. Our look at how accurate tags really are sets out where the error actually comes from.
If your losses are of the "which room, which building, which café" variety — and for most households they are — waiting eighteen months for a feature that improves the last three metres is a poor trade against covering five objects now. If your losses genuinely are the last-three-metres kind, buy the Ultra Wideband hardware that exists today rather than waiting for a cheaper version of it.
What channel sounding will eventually change is the price of that capability, not whether it exists. That is worth something, and it is worth watching. It is not worth postponing a decision over.
How BlueTag stands in relation to all this
BlueTag does not have channel sounding and cannot acquire it. It is a broadcast-only Bluetooth Low Energy device, and we would rather write that sentence here than let a version number on a box imply otherwise. Nor does it carry Ultra Wideband, so neither an arrow nor a distance readout ever appears on screen.
What it has instead is the pair of mechanisms that do the actual work for most losses: a link of up to 60 m / 200 ft over which your iPhone can set off an 80–100 dB buzzer, and the Apple Find My network past that, where passing Apple devices report an encrypted position only your Apple Account can decrypt. Our piece on what the Bluetooth specification says about broadcasting explains why that design is what buys the battery life.
The rest is fixed and unglamorous: an MFi certified case sealed to IP67, measuring 36.3 × 36.3 × 9 mm at roughly 10 g, powered by a CR2032 the owner swaps every couple of years. An iPhone or an iPad running iOS 14.5 upwards is required, and Android is not supported. A box holds two of them plus two key rings, posted free within the UK, returnable for thirty days, under £15. See the specification.
Sources
- Silicon Labs, 4 August 2026 — Silicon Labs unveils BG2B, its lowest-power Bluetooth LE SoC
- CNX Software, 4 August 2026 — BG2B is the lowest-power Bluetooth LE SoC from Silicon Labs so far
- Bluetooth SIG — the Core 6.0 specification, where ranging was first defined
- Bluetooth SIG — Bluetooth Core 6.2 feature overview, released 4 November 2025
From the desk of Bluetooth Tracker Last revised
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