VHF for RTLS: phase ranging across halls and yards
A plant spans three halls and an outdoor yard. Hundreds of tagged returnables and tuggers move across that footprint. The logistics lead needs one location layer for the full halls, not a dense locator roof in every bay. That full-hall, multi-hall, high-count job is where VHF phase ranging often makes sense. This page explains what it is, how it gets a location, where it is strong, where it is weak, and when to pick it.
What VHF is on the floor
VHF phase ranging is an indoor and outdoor RTLS method. Fixed gateways broadcast unmodulated VHF carriers, typically in fine sub-bands around 148–174 MHz (subject to national allocation). A tracker on a person, vehicle, or asset receives those carriers, measures phase, separates the direct path from reflections, and computes its own position on the device. The location is not signal loudness and not a dense ceiling pulse grid.
VHF is one technology family among peers. Its strengths show up on a full hall, across multi-hall sites, and when there are a lot of assets to track on one sparse gateway layout. People and vehicles can also move through walls and between indoor and outdoor lanes on the same stream. In automotive plant deployments, about 3 m (10 ft) of accuracy is a realistic planning floor with four VHF antennas across roughly 40,000 m² (about 430,000 ft²). Treat that as a starting guide, then walk a pilot area on your own floor with inventory in place to see if it still holds. Match the job to the technology first. The decision order sits under start with the decision, not the technology. The wider menu is in RTLS technologies out there.
How VHF gets a location
1. Gateways transmit VHF carriers - Fixed stations emit the unmodulated carriers. Placement and antenna height set coverage. The stack runs on a sparse count of gateways compared with a roof of short-range locators.
2. The tracker computes position on the device - The module measures phase across the carriers, runs an algorithm that isolates the direct path from multipath, and outputs coordinates locally on the tracker.
3. A backhaul pipe moves the result - After the tracker knows where it is, it typically sends the small position packet on a private LoRa / LoRaWAN network. One LoRa gateway is often enough next to four VHF antennas on a hall of that size. From there the stream enters the plant over Ethernet or LTE (4G / 5G). LoRaWAN is the pipe. It does not create the VHF phase location.
Strengths
Full-hall coverage - Low-frequency carriers penetrate concrete and building fabric, so a few gateways can cover an entire hall without carpeting every aisle in short-range anchors.
Multi-hall and campus continuity - The same stack can follow assets across halls and outdoor yards on one map, without handing off to GPS at every door.
Lots of assets on sparse infrastructure - When tag count is high (returnables, vehicles, people), the cost story sits on the trackers and a small gateway set, not a dense locator roof that grows with every bay. On-device position calculation and a light backhaul pipe support that scale. Medium-precision search accuracy (about 3 m / 10 ft) fits hall and campus jobs when that band is enough.
Weaknesses
VHF carriers sit on government-controlled bands. Each country needs an approved frequency range before gateways can transmit. That licensing step is part of the RF plan, not an afterthought. Hardware is a specialist stack, not commodity phone silicon. About 3 m (10 ft) is a planning floor for many plant deploys, not a painted centimetre (inch) cell. Brochure claims still need a site survey on your floor. Tracker and gateway spares follow the proprietary path. Put licensing, survey, and mount labour on the payback sheet in what to include when calculating RTLS ROI.
When VHF fits
1. Name the scale job - Full-hall coverage, multi-hall continuity, or a large asset count that must share one sparse gateway layout. If the answer can be wrong by about 3 m (10 ft) and still work, VHF is in that accuracy band.
2. Check spectrum and site - Confirm national band approval before you buy. Survey gateway height and count on your layout. Start with a pilot walk on your campus before you roll the same layout site-wide.
3. Separate location from pipe, then land one map - VHF phase creates the location. LoRaWAN, Ethernet, or LTE moves it. 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 VHF when you need full-hall or multi-hall reach for many assets, and its weaknesses are acceptable on your campus. Get in touch if you want to walk that choice on your own facility model.