License Plate Cameras Are About to Track Your Phone, Smartwatch, and Even Your Pets
Most people already know that traffic cameras can read license plates. What fewer people realize is that the next generation of those same cameras may also be quietly harvesting the unique wireless identifiers broadcast by every smart device in your vehicle — your phone, your AirPods, your smartwatch, your car's infotainment system, and possibly even your pet's microchip. That future is closer than you think, and a defense contractor called Leonardo is already marketing the technology to law enforcement agencies.
What Is SignalTrace and Who Is Behind It?
Leonardo is a major defense and aerospace contractor with an established customer base that includes police departments, border security agencies, and other government clients. The company is now promoting a new surveillance product called SignalTrace, which pairs traditional automatic license plate reader (ALPR) cameras with sensors capable of scraping the unique identifiers broadcast by nearby wireless devices.
A detailed report by 404 Media first brought SignalTrace to wide public attention, revealing how the system is being positioned as a tool to help law enforcement correlate physical vehicle sightings with a web of connected devices. Rather than simply capturing a plate number and moving on, SignalTrace-equipped cameras would simultaneously log the wireless signals of every smart device within range of the camera — building a far richer data profile with every single pass.
The implications of that capability are enormous. Where traditional ALPRs tell authorities where a car was and when, SignalTrace promises to tell them which devices were inside that car, who those devices likely belong to, and where those same devices turn up next.
Which Devices Can SignalTrace Actually Track?
The scope of what SignalTrace is designed to detect is broader than most people would assume. According to the marketing materials reviewed by 404 Media, the system is intended to pick up unique identifiers from a wide range of consumer electronics and connected devices, including:
- Smartphones and tablets — the most obvious targets, broadcasting Bluetooth and Wi-Fi signals constantly in most default configurations.
- Wearables — smartwatches, fitness trackers, and wireless earbuds like AirPods all broadcast Bluetooth identifiers that can be linked back to a specific user account.
- AirTags and similar tracking devices — ironically, the very products marketed to consumers as personal trackers become additional data points for third-party surveillance.
- Vehicle infotainment systems — modern cars are rolling wireless hubs. Their built-in navigation, entertainment, and connectivity systems broadcast identifiers just as phones do.
- 5G hotspots — many vehicles now include built-in cellular hotspots, each with a unique hardware identifier.
- Tire pressure monitoring sensors (TPMS) — these small, low-power sensors mounted inside each tire broadcast short-range radio signals, and they too carry unique identifiers.
- Pet microchips — perhaps most surprising of all, Leonardo's materials reportedly list pet microchips as a potential data source, meaning even your dog or cat could become an involuntary tracking anchor tying you to a location.
Each of these devices broadcasts a hardware identifier that, once logged, can be correlated with other sightings across a network of cameras. Travel past enough SignalTrace units and the system can reconstruct a detailed map of where you go, when you go there, and who or what you travel with.
Why This Is a Significant Escalation in Surveillance Capability
Automatic license plate readers are not new. Law enforcement agencies across the United States and around the world have deployed ALPR systems for years, building databases of vehicle movements that civil liberties advocates have long criticized as a form of warrantless mass surveillance. Courts have wrestled with how to apply Fourth Amendment protections to data that is technically collected in public spaces.
SignalTrace represents a qualitative leap beyond that existing debate. A license plate is registered to a vehicle. A vehicle can change hands, be borrowed, or be rented. But a smartphone's hardware identifier is tied to a specific device, and that device is typically tied to a specific person through their Apple ID, Google account, or carrier contract. Wireless device identifiers don't change when you loan someone your car.
This also intersects directly with the data broker ecosystem. Data brokers have for years purchased device location data from app developers and ad networks, assembling detailed profiles of individuals' movements and behaviors. When a surveillance vendor like Leonardo begins collecting and packaging similar device-level identifiers — and making that data available to law enforcement clients — it effectively merges the commercial surveillance economy with state power in a single hardware unit bolted to a pole above a highway.
What Are the Privacy Concerns?
Privacy advocates argue that systems like SignalTrace normalize a level of persistent, automated tracking that would have required extensive physical resources just a decade ago. A driver passing through a city equipped with SignalTrace cameras wouldn't simply have their plate logged. They'd have every wireless device in their possession catalogued and cross-referenced, potentially without any individualized suspicion, judicial oversight, or even awareness.
The inclusion of tire pressure sensors and pet microchips in Leonardo's device list is particularly telling. These are not communication devices in any meaningful sense — they are passive hardware components attached to personal property. Their inclusion signals an intent to cast the widest possible net, capturing any unique identifier that can anchor a person to a place and time.
What Can You Do to Protect Yourself?
There are practical steps that privacy-conscious individuals can take, though none are foolproof. Enabling Bluetooth and Wi-Fi only when actively needed reduces the window of exposure. Some devices offer randomized MAC addresses, which can limit persistent tracking across sessions. Keeping devices in airplane mode while driving is more aggressive but substantially reduces the wireless footprint a system like SignalTrace could capture.
Longer term, meaningful protection is likely to require legislative action. Several U.S. states have introduced or passed laws restricting how ALPR data can be stored and shared, and similar frameworks governing wireless device scanning in public spaces are a logical next step — though they lag far behind the technology itself.
The Bottom Line
SignalTrace is a clear signal of where mass surveillance is heading. By bundling device-scraping sensors with license plate cameras already trusted by law enforcement, Leonardo is positioning itself to sell authorities not just a record of where your car was, but a comprehensive wireless fingerprint of everything and everyone inside it. As these systems become more widely deployed, the question of what privacy looks like in a public space will become impossible to ignore.