How GPS jammers impact fleets

Commercial fleet owners and operators have seen an industry-wide shift toward integrated, connected technology. GPS tracking, telematics and real-time data help companies streamline operations, promote safer driving and maintain compliance. But one growing risk threatens that visibility: the GPS jammer.

A GPS jammer — sometimes called a GPS blocker, GPS signal jammer, GPS signal blocker or telematics jammer — can interfere with the Global Positioning Systems (GPS) tracking solutions that fleets rely on every day. While these devices are illegal in the U.S., they are still sold online and can disrupt fleet visibility, safety oversight and day-to-day control.

Understanding what GPS jammers are, how they work, what they look like and how they impact your fleet is critical to protecting your vehicles, drivers and operations. This guide explains the essentials and outlines how to detect and mitigate GPS signal blocking before it becomes a costly problem.

What is a GPS jammer and how does it work?

A GPS jammer is a small, high-power radio frequency (RF) transmitter that blocks or interferes with lawful communication signals. These devices can disrupt GPS satellite signals, cellular networks, Wi-Fi and even toll readers.

GPS receivers rely on low-power microwave signals broadcast from GPS satellites. A GPS jammer works by overpowering these satellite signals with a stronger, short-range RF signal that creates “noise.” When this happens, the vehicle’s GPS hardware cannot process satellite data. In some cases, the signal is overwhelmed entirely; in others, the jammer generates misleading information — a tactic often referred to as spoofing.

More advanced GPS jammer models take this a step further. Some rapidly hop between frequencies or target multiple GNSS constellations such as GPS, GLONASS and Galileo. Others can interfere with cellular networks at the same time. These capabilities make the GPS jammers harder to detect and can disrupt more than one system at once.

Types of GPS jammers

GPS jammers come in several forms, each built to interfere with location data in different ways. While they vary in size, power and complexity, they all disrupt the signals that telematics systems rely on to provide accurate tracking.

• Portable jammers: The most common GPS jammer, these small plug-in or battery-powered devices are often used to hide a vehicle’s location from tracking systems. Their range is limited, but they can still create localized GPS outages that affect nearby vehicles or equipment.
• Vehicle jammers: Hard-wired or mounted inside a vehicle, these typically block multiple signals at once. Many models interfere with GPS, cellular and Wi-Fi frequencies simultaneously, making them useful to individuals trying to disrupt both navigation data and connected fleet communications.
• Stationary jammers: These are higher-power systems that operate from a fixed location. More common outside the United States, these devices can blanket a much larger area and disrupt multiple GNSS constellations at the same time, affecting not just a single vehicle but an entire zone.
• GPS spoofers: These operate differently from jammers but are often grouped in the same conversation. Instead of blocking GPS signals, they imitate legitimate satellite transmissions to feed false location data to telematics systems. This can cause a vehicle to appear in the wrong place, follow an impossible route or remain stationary when it’s actually moving.

What GPS jammers look like

Since devices that can block GPS signals come from a number of manufacturers, they vary greatly in shape, size and dimensions, making them hard to spot within a driver’s vehicle. Most commonly, GPS blockers are small enough to fit in a hand or glove box and plug into a 12-volt port, USB charger or cigarette lighter.  They may resemble a cell phone, portable battery pack or Wi-Fi hotspot. All this makes them difficult to spot visually, especially when hidden among personal items in the cab.

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Are GPS jammers illegal?

GPS jammers are illegal in the United States and Canada. GPS jamming devices can prevent a driver or others on the road from making 9-1-1 and other emergency calls, and they can interfere with communication networks utilized by police, fire and emergency medical services, impacting public safety. Because of these significant risks, it is illegal to operate, market, sell or ship GPS jammers.1

Despite this, many are still sold online. Drivers may unknowingly violate federal law by using them, exposing themselves and employers to penalties.

How GPS jammers impact fleets

Fleet operations depend on accurate GPS data for routing, safety monitoring, compliance and maintenance. Jamming interrupts that visibility.

• Loss of location visibility: Fleets cannot see where vehicles are, how long routes take or whether drivers remain on schedule. This makes it more difficult for fleet managers to track progress, respond to issues or help in effective route planning and adjustments for efficiency — ultimately leading toward greater mileage, longer travel times, increased fuel usage and higher operational costs.
• Missing or inaccurate safety data: GPS jammers prevent identification of speeding, harsh driving and hours-of-service compliance. In the case of a breakdown or accident, vehicles may be difficult to find, wasting time and resources and jeopardizing driver safety.
• Reduced theft recovery: A jammed GPS unit makes a stolen vehicle harder to track or recover.
• Incorrect maintenance reporting: Mileage, engine hours and utilization data may be incomplete, affecting preventive maintenance.
• Compliance challenges: Gaps in required telematics data can lead to audits, fines or regulatory violations.
• Operational and financial disruption: Service delays, missed appointments and increased administrative work can all stem from lost tracking data.

The inability to accurately measure this type of data can result in compliance audits, fines, and situations where vehicles aren’t properly maintained — ultimately impacting revenue and fleet safety.

How to detect possible GPS jamming

While it’s difficult to spot a jammer, fleet owners, operators and managers can spot the signs. Verizon Connect’s fleet management platform can actually help you recognize if and when a device is being potentially hampered by a GPS jammer. The following may be signs of GPS blocking:

• Monitor Non-Reporting Unit (NRU) trends: A sudden spike in devices dropping offline or failing to update can indicate that something is blocking their ability to acquire a GPS signal.
• Notice when GPS data doesn’t match driver activity: See if the route history shows gaps, impossible jumps or periods of “no movement” when a vehicle was known to be active.
• See simultaneous loss of GPS and cellular signals: Losing both at the same time — especially in areas that normally have coverage — can suggest a multi-band jammer affecting multiple frequencies at once.
• Drivers experience navigation app issues: Repeated “GPS signal lost” alerts, frozen maps or erratic rerouting on driver smartphones can mean interference.
• Discover anomalies during specific hours or routes: If vehicles consistently lose GPS in the same area or at the same time of day, it may point to a jammer operating near that location.

How fleets can prevent and mitigate GPS jamming

The most effective way to avoid GPS jamming is to prevent it before it disrupts operations. Clear policies, consistent monitoring and proactive maintenance give fleets the best chance to catch issues early and limit the impact of interference. These steps can help protect your systems and reduce risk:

• Set clear policies and educate drivers: Clearly communicating with employees the company’s vehicle usage policies, and policies around illegal devices like GPS jammers, can help discourage use of such devices in the first place.
• Secure hardware installation: Hidden or tamper-resistant installation reduces the chances of interference, one of the benefits of professional telematics installation.
• Perform regular IT and device maintenance: Keeping a regular schedule of IT network maintenance and troubleshooting to offset the possibility of data tampering can go a long way toward preventing future issues. 
• Investigate anomalies quickly: Address issues before they cause widespread operational disruption. Spotting the anomalies above is worth a quick investigation.

Learn more about how video and telematics strengthen fleet security here.

Strengthening fleet safety with reliable connected technology

GPS jammers threaten the reliability of the systems fleets depend on. But with the right approach, these risks can be identified and mitigated. By understanding how GPS jammers work, watching for warning signs and leveraging a secure telematics platform, fleet managers can maintain visibility, ensure compliance and protect people and assets.

Want to learn more about how Verizon Connect Reveal’s secure network supports fleet management software with greater uptime? Book a demo today.

Sources:

1 Cell Phone and GPS Jamming, Federal Communications Commission