Law enforcement has long relied on automatic license plate recognition cameras to spot vehicles connected to crimes, but the next generation of surveillance could go far beyond reading plates. A new sensor system called SignalTrace is being pitched to police agencies as a way to tie the electronic signals from phones, laptops, smartwatches, and other devices to specific vehicles. If adopted, the technology would give investigators another powerful method for tracking cars — while raising serious questions about privacy and civil liberties.

Key facts

• SignalTrace is a sensor system by Leonardo US Cyber and Security Solutions designed to detect Bluetooth, Wi-Fi, and RFID signals from nearby electronic devices.
• The system is intended to work alongside automatic license plate recognition (ALPR) cameras, such as those made by Flock.
• By analyzing recurring patterns, SignalTrace could help associate a group of device signatures with a particular vehicle and, eventually, with a registered owner.
• Leonardo says the system does not identify individuals by itself, but privacy advocates warn that combining it with ALPR data can lead to identification.
• The technology is still being pitched and is not yet deployed in the real world.

What is SignalTrace?

SignalTrace is a sensor technology developed by Leonardo US Cyber and Security Solutions, a defense and security company. It is designed to detect electronic signals emitted by consumer devices, including Bluetooth beacons, Wi-Fi probes, and RFID chips. Every smartphone, laptop, smartwatch, wireless earbud, and many other gadgets constantly emit low-level signals to connect with networks and other devices. These signals are not random; they contain unique identifiers that can be observed and logged by receivers.

Leonardo describes SignalTrace as a way to collect electronic signatures from the environment. The company says these signatures are not personally identifiable by themselves. However, the system is not meant to work alone. It is designed to be deployed alongside ALPR cameras, which identify vehicles by their license plates. Together, the two systems could create a powerful surveillance network that links physical vehicles to the digital devices inside them.

How the tracking would work

The proposed system would work by placing SignalTrace sensors at the same physical locations as ALPR cameras. When a car passes through an intersection or enters a parking lot, the ALPR camera records its license plate. At the same moment, the SignalTrace sensor captures the Bluetooth, Wi-Fi, and RFID signatures of any electronic devices in or near the vehicle.

Imagine a person who commutes to work every weekday. Their car passes the same ALPR camera each morning. The camera logs the plate, while the SignalTrace sensor logs the same group of device signatures: a phone, a smartwatch, and a laptop bag with a Bluetooth tracker. Over time, the system identifies a recurring pattern. That specific cluster of device signatures always appears with that license plate. The system then associates the devices with the vehicle.

From that point on, investigators can track the vehicle in another way. If the driver covers the license plate, swaps it, or goes out of view of ALPR cameras, the device signatures may still be visible to SignalTrace sensors in other locations. Police could search for the known electronic signature cluster across a network of sensors and find the vehicle — or at least the devices traveling with it.

Leonardo says it does not identify people

Leonardo has been careful in its public statements about privacy. The company says that SignalTrace only collects electronic signatures and that those signatures, by themselves, do not identify a person. That statement is technically true. A MAC address or Bluetooth identifier is not a name, address, or Social Security number.

But privacy experts point out that the system is not designed to work by itself. It is designed to work with ALPR data. Once a cluster of device signatures is consistently associated with a specific license plate, and that license plate is registered to a person, the electronic signatures become a proxy for that person's identity. In other words, the system may not start with a name, but it can get to a name very quickly.

The concern grows when considering how the data could be used after a vehicle is linked to a person. With enough SignalTrace sensors in place, law enforcement could build a detailed timeline of where a person's devices have been. That timeline could reveal their home address, workplace, daily routines, social contacts, and even visits to sensitive locations such as medical clinics or places of worship.

What SignalTrace could help police do

Supporters of the technology argue that SignalTrace could be a valuable tool for legitimate law-enforcement work. One obvious use case involves fleeing vehicles. Many criminals know that ALPR cameras are everywhere, and they may take steps to avoid them by covering their plates or using stolen plates. With SignalTrace, police could identify a vehicle by its device signatures instead of its plate.

For example, if a car is linked to a suspect in a crime, investigators could pull the historical device signatures associated with that license plate. They could then search for those signatures in other places where the vehicle was spotted, even if the plate was changed. This might help locate a vehicle that has otherwise gone off the grid.

The technology could also assist in finding stolen cars, tracking vehicles involved in kidnappings, or identifying cars connected to repeated crimes in a neighborhood. In cases where traditional plate reading fails, device-signature matching could provide an alternative route.

The danger of false flags

The same capability also creates a serious risk of false flags. Consider a scenario where police are tracking a vehicle connected to an investigation. The system has linked a particular phone to that vehicle. One day, the person lends their car to a friend, spouse, or coworker. The device signatures that police are looking for now appear in a different vehicle.

Because the system has already associated those electronic signatures with the first vehicle, the second vehicle may suddenly become a subject of interest. The owner of the second vehicle might have nothing to do with the crime, but their car could be flagged based on nothing more than the fact that they were driving near someone else's devices.

Even more concerning is the possibility of guilt by association. If a person accused of a crime has their device signatures tracked, and those signatures later appear in the car of a neighbor or an Uber driver, the system could imply a connection that does not exist. The technology does not understand context the way a human investigator would. It simply sees patterns and flags matches.

A broader surveillance shift

SignalTrace is part of a broader trend toward multi-layered surveillance. ALPR cameras have become commonplace across the United States. Companies like Flock have installed networks of cameras in residential neighborhoods, business districts, and highways. These cameras are marketed as tools for fighting crime, but they have also been criticized for creating permanent records of nearly every vehicle that moves through a city.

Adding device-signature sensors to the same poles and intersections would greatly expand the scope of what police can know. A person might be able to avoid bringing a phone when they drive a car, but it is nearly impossible to avoid emitting some form of digital signal. Modern vehicles themselves contain Bluetooth and Wi-Fi modules. Smartwatches, fitness trackers, tire-pressure sensors, and toll transponders all produce electronic signatures. Even a person who deliberately leaves home without a phone could still be tracked by other devices in their pocket or car.

Once these systems are deployed, retroactive privacy is difficult. The data collected by SignalTrace sensors might be stored for months or years, creating a searchable archive of location histories. Law-enforcement agencies could query that archive not only for known suspects, but also for unknown people who happened to appear near a crime scene.

Legal and policy hurdles

The legal status of device-signature tracking is still unclear. The U.S. Supreme Court has ruled that tracking a person's location through a cell phone requires a warrant in many circumstances, but those rulings were based on the specific nature of cell-site records. It is not yet clear how a court would treat Bluetooth and Wi-Fi signatures collected by stationary sensors.

Police may argue that SignalTrace is no different from an ALPR camera, which is typically considered a tool that records what is in public view. However, privacy advocates are likely to counter that electronic signals are not the same as a visible license plate. A plate is displayed intentionally on the outside of a vehicle. A Bluetooth or Wi-Fi signal is generated by personal devices, often without the owner's knowledge or consent, and can be used to infer far more sensitive information.

Another issue is data access and retention. If SignalTrace data is stored in centralized databases, questions arise about who can access it, how long it can be kept, and whether civil-rights organizations can audit its use. Without clear rules, the potential for abuse is significant.

Leonardo says the system is not yet in the real world, but the company is actively pitching it to law-enforcement agencies as an addition to existing ALPR systems. Whether it becomes a core part of police surveillance remains to be seen. What is certain is that the line between our physical presence and our digital presence is becoming thinner every year, and technologies like SignalTrace are designed to exploit that connection.

Source:Android Authority News