VHF for RTLS: phase ranging across halls and yards
If one sparse gateway layout has to cover full halls, multi-hall campuses, and mixed indoor-outdoor moves, VHF phase ranging is the RTLS option plants put on the shortlist. This page covers how it locates trackers, what it does well, and when it is the wrong buy.
What VHF is
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 comes from measured phase across those carriers, not from signal loudness and not from a dense short-range ceiling grid.
VHF is one technology family among RTLS peers. It is built for a full hall, for multi-hall campuses, and for a large asset count that must share one sparse gateway layout. The same stream can follow people and vehicles through building fabric and between indoor lanes and outdoor yards. In automotive plant deployments, about 3 m (10 ft) of accuracy is a realistic planning baseline with four VHF antennas across roughly 40,000 m² (about 430,000 ft²). Treat that figure as a starting guide, then walk a pilot area on your own floor with inventory in place. 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 uses a sparse gateway count compared with a dense ceiling grid 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. A few gateways can cover an entire hall, so coverage spend does not have to follow every aisle with short-range anchors.
Multi-hall and campus continuity - The same stack can follow assets across halls and outdoor yards on one map, including moves that leave the roof. That continuity case is spelled out in indoor and outdoor on the same move and in different buildings across two square kilometres.
Lots of assets on sparse infrastructure - When tag count is high (returnables, vehicles, people), spend sits on the trackers and a small gateway set, not on a locator roof that grows with every bay. On-device position calculation and a light backhaul pipe support that scale. About 3 m (10 ft) is medium-precision location, which fits hall search, asset tracking, and campus continuity when that band is enough for the shift question.
Weaknesses
VHF carriers sit on government-controlled bands. Each country needs an approved frequency range before gateways can transmit. That licensing step belongs in the RF plan, not after purchase. Hardware is a specialist stack, not commodity phone silicon. About 3 m (10 ft) is a planning baseline for many plant deploys, not exact floor position on a mark. Brochure claims still need a site survey on your floor with inventory in place. 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 sits in that accuracy band. The same continuity test applies when forklift tracking or industrial fleet management must stay visible through walls and into the yard on one tag.
2. Check spectrum and site - Confirm national band approval before you buy the equipment. Survey gateway height and count on your layout. Prove coverage on a campus pilot before you copy 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. 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.