UWB for RTLS: time of flight for a tight floor location
A torque tool sits tagged at Cell 7. The planner needs utilization by hour, not a clipboard guess. The same cell runs a rule that must not start the next sequence until that tool is actually at the station face. “Somewhere near Line 3” fails both jobs. That is one of the jobs ultra-wideband (UWB) is built to answer. This page explains what UWB is, how it gets a location, where it is strong, where it is weak, and when to pick it.
What UWB is on the floor
UWB is a short-pulse radio used for indoor RTLS. Tags and fixed anchors exchange very short pulses. The location engine measures time of flight: how long the pulse took to travel, then converts that time into distance. Under clean line of sight, industrial installs often hold sub-metre (~3 ft) location, commonly on the order of 10–30 cm (4–12 in).
UWB is one technology family among peers, not a default end state for every plant. Plants use it for tool utilization at a work area, rule-engine sequences, dock-face confirmation, exact floor position, and the same continuous tracking jobs other RTLS radios cover when the hall can keep line of sight. Many no-go zones can run at medium precision on another radio instead. Anchor density, update rate, tag power, and TWR versus TDoA still decide battery life and cabling. Match the job to the technology first, then the build inside it. The decision order sits under start with the decision, not the technology. The wider menu is in RTLS technologies out there.
How UWB gets a location
1. Two-way ranging (TWR) - Tag and anchor exchange pulses. The stack measures round-trip time, subtracts known processing delay, and keeps the range. TWR does not need the whole network locked to one clock. It fits tools, forklifts, badges, and other assets that need continuous location without full anchor sync.
2. Time difference of arrival (TDoA) - The tag blinks once. Several synchronized anchors compare when that pulse landed. Position comes from the time differences. Efficient when many tags must update often. The cost sits on sync, survey, and denser infrastructure.
Both methods depend on the first path. If the engine times a bounce instead of the direct path to the antenna, the clock is precise about the wrong length. That is why NLOS and multipath matter as much as the datasheet centimetre (inch) line.
Strengths
Tight, trustworthy location when line of sight holds. Strong for tool utilization by cell, sequence and rule engines that must wait until an asset is truly at the station face, geofences and safety cells that need inside-versus-outside truth, and continuous tracking of vehicles, people, or loads when the plant wants that precision on one radio family. Time-based ranging, not signal loudness, underpins those jobs.
Weaknesses
For best results the tag needs direct line of sight to enough anchors. That is the biggest downside in cluttered areas. Loaded racking, mezzanines, stacked cages, and tall WIP walls block or bend the first path. Empty-lab numbers fail in production clutter. Faster updates cost tag battery unless the tag is wired to vehicle power. Dense anchors mean cabling and survey. Run a short coverage map on a real work pocket first, then expand only where the first path stays clean. The lab-versus-floor gap is walked in ask for a coverage map, not 30 cm (12 in) on the slide. Cost traps sit in what to include when calculating RTLS ROI.
When UWB fits
1. Name the decision that needs a reliable place - Tool utilization by cell, a sequence gate, exact floor position, dock-face confirmation, or continuous search where a few tens of centimetres (about a foot) matter.
2. Check line of sight on the real layout - If clutter will block anchors, budget density, remounts, or accept that this pocket is a weak fit until the layout changes.
3. Choose TWR or TDoA, then land one map - TWR when sync is hard and assets are few. TDoA when many tags must blink often. Then put the stream on one digital twin for internal logistics optimization and production monitoring. Peer technology pages for other radios sit under the survey linked above. Definitions start at what is RTLS. Product capabilities are on the features overview.
Pick UWB when its strengths match the job and its weaknesses are acceptable on your floor. Get in touch if you want to walk that choice on your own facility model.