GPS Jamming – The RISKs are REAL
And Very Much Worth Understanding
The Global Positioning System (GPS) is one of those ubiquitous technologies that powers an inordinate amount of our daily lives, and moreover, the global economy, yet most people are oblivious to it. GPS is literally everywhere around the globe and truly is indispensable. It is in your car, your smartphone, maybe even your watch. It helps you get from point A to point B without a second thought. The importance of GPS is signified as follows:
The U.S. Department of Defense is required by law to “maintain a Standard Positioning Service (as defined in the federal radio navigation plan and the standard positioning service signal specification) that will be available on a continuous, worldwide basis“ and “develop measures to prevent hostile use of GPS and its augmentations without unduly disrupting or degrading civilian uses”.
GPS is a set of radio technologies and related systems that falls within the larger category of Global Navigation Satellite System (GNSS). As of 2020, there are three fully operational GNSS systems:
The U.S. navigation signal timing and ranging (NAVSTAR) GPS
Russia’s Global Navigation Satellite System (GLONASS)
Europe’s Galileo system
Though GPS technology is a subset of GNSS, receivers are differentiated as GPS only, or as GNSS. A GPS receiver is only capable of reading information from satellites in the GPS satellite constellation. A typical GNSS device can receive information from both GPS and GLONASS (or more than these two systems) at a time.
Because many of the global GNSS systems use similar frequencies and signals as GPS, around the L1 frequency spectrum, many “Multi-GNSS” receivers capable of using multiple systems have been produced.
The NAVSTAR GPS consists of 32 satellites owned by the U.S. and is the best-known and most widely utilized satellite positioning system. Russia’s GLONASS consists of 24 operational satellites with three used as spares and/or for use in testing.
GPS receivers—whether they are installed in ships at sea or embedded in a smartphone or a wristwatch—calculate their latitude, longitude and altitude by measuring the relative time delay of signals broadcast by at least four different satellites. Ground control systems, consisting of six monitoring stations, four ground antennas and Schriever’s master control station (MCS), communicate and operate the NAVSTAR satellites via communications from the ground antennas.
GPS Jamming - why do we need to care about it?
Because large swaths of the global economy, global navigation, aviation, and everyday basic security depend on GPS, the threat of disruption to GPS has major implications. It is very easy for crooks and other bad actors to leverage GPS jamming to support efforts in the drug trade, cargo theft and a host of other illicit activities. Drug traffickers regularly use jammers to try to foil electronic surveillance by law enforcement or rival gangs. The shipping security firm FreightWatch reported last year (2024) that there have been at least four large scale cargo thefts that were foiled in which GPS jamming devices were recovered. Simple jamming devices, despite being illegal to possess in the US, can be purchased for less than $200.00.
In 2013, the Federal Communications Commission fined a person almost $32k for using a device intended to evade the fleet management tracking system on his company vehicle. The device in question: a $30 GPS jammer.
For more than two years the FAA and New Jersey Port Authority were unable to determine why a new ground-based augmentation system (GBAS) – a flight system used primarily for augmenting aircraft take-off and landing at the Newark airport continued to experience intermittent failures. The cause of the failures was unknown. Leveraging specialized equipment, the culprit was finally identified. A contractor on site at the airport was using a GPS jammer that not only blocked his company vehicle’s fleet tracking system, it also took down the airport’s GBAS in the process.
A simple jamming device was able to take down a state-of-the-art, highly sophisticated aircraft landing system at one of the busiest airports in the world. Of note, this user was NOT trying to interfere with airport operations. Imagine what a person who DID intend to do harm to airport operations could do?
GPS is used for much more than just navigation. It’s also the primary source of timing and synchronization used in critical infrastructures such as financial, communications, industrial, the electric power grid, and more.
Jamming and Spoofing – so simple a child can do it!
Jamming is one challenge. Spoofing GPS devices is yet another challenge. GPS is susceptible to jamming and spoofing because its satellite signals arrive at the earth’s surface with extremely low power. GPS consists of three components: satellites, receivers and ground control stations (see GPS basics below). GPS spoofing and jamming are attacks that interfere with GPS signals. GPS jamming occurs when an external entity disrupts GPS signals by overwhelming them with noise or interference. This prevents receivers from determining an accurate location, leading to navigation failures, positioning errors, and loss of tracking.
Spoofing sends fake signals to trick GPS devices into showing incorrect locations, while GPS jammers block signals altogether, causing loss of service. GPS spoofing manipulates GPS signals to deceive receivers into believing they are in a different location.
Jammers broadcast noise on GPS frequencies, primarily L1 (1575 MHz) and L2 (1227 MHz), but at a higher power to drown out satellite signals. This makes it impossible for the GPS receiver to distinguish between the legitimate signal and the interference. The receiver is overwhelmed and fails to provide accurate positioning data. The three primary methods used in jamming include:
Continuous Wave (CW): Concentrates full power on one frequency using a steady sinusoidal signal for targeted blocking.
Sweep or Barrage: Often referred to as chirp jamming, these devices transmit across a band of frequencies and rapidly shift frequencies, typically between 1565-1585 MHz. In this way they can often overpower an entire range of signals rather than a single frequency.
Directional: Uses antennas to aim interference at specific targets, such as drones or vehicles.
GPS jammers can be as simple as a device that plugs into a vehicle’s cigarette lighter port and are often marketed as anti-tracking tools despite legal restrictions. These types of devices are typically used to disable tracking in trucks and cars and broadcast on the L1 band at approximately 10mW.
Larger, complex, and more bulky devices with dozens of antennas, often referred to as hedgehog jammers (due to their many antennas) typically broadcast on the L1 or L2 band with around 10W of power. These jammers are often used by criminals seeking to jam multiple radio signals at the same time such as WIFI, GPS, and cellular signals and can cover kilometers – to disable alarm systems, hide the location of contraband or stolen materials, or prevent satellite-based navigation/tracking services.
NOTE: In many countries, including the United States, the use of GPS jammers by civilians is illegal. The US Federal Communications Commission (FCC) prohibits the sale, marketing, and use of any device that intentionally interferes with authorized radio communications because of the risk to public safety.
It is also possible for satellite malfunctions and/or solar flares to temporarily disrupt the transmission of GPS signals.
Consumer Facing Deployments
There are literally thousands of consumer and public applications and programs that rely on a robust secure GPS system. Some of them include:
Civilian aviation/aircraft tracking relies on GPS.
Global marine navigation relies on GPS.
Disaster relief/emergency services - many emergency services depend upon GPS for location and timing capabilities.
Geofencing/Geotracking use GPS to locate devices that are attached to or carried by a person, vehicle, or pet.
Vehicle fleet operations - used to identify, locate and maintain contact with fleet vehicles in real-time for route optimization and operational efficiencies.
Automobile navigation tools/software up to and including autonomous driving systems heavily leverage GPS.
Satellite tracking and orbital operations including collision avoidance systems use GPS signals.
Surveying/Tectonics/Mining - surveyors use absolute locations to make maps and determine property boundaries, and GPS enables direct fault motion measurement of earthquakes and to measure crustal motion and deformation.
Telematics - where GPS technology is integrated with computers and mobile communications technology in automotive navigation systems.
Military Deployments
Military uses, not surprising, are also varied and diverse and include navigation over air/land/sea, radio clock synchronization, target tracking, missile and projectile guidance, satellite operations, and even nuclear detonation detection.
Fun Fact – GPS Break Through
GPS played a critical role in the 1991 Persian Gulf War, so much so, that this conflict has been characterized as was the worlds’ first “space war”. GPS supported U.S. and Coalition forces with navigation and position tracking. The first gulf war also demonstrated the susceptibility of GPS to being jammed. Iraqi forces installed jamming devices on likely targets that emitted radio noise, disrupting reception of the weak GPS signal.
More recently, in the current Russo-Ukrainian War, Ukrainian GPS-guided munitions have experienced significant failure rates resulting from Russian electronic warfare against GPS systems.
GPS Basics
The GPS project was launched in the United States in 1973 to overcome limitations of previous navigation systems. The U.S. Department of Defense developed the system, which originally used 24 military satellites, and it became fully operational in 1993. Civilian use (with limited capabilities) went operational in the mid-1980s.
The work of Gladys West on the creation of the mathematical geodetic earth model is credited as instrumental in the creation of computational techniques for detecting satellite positions with the precision needed for GPS. Mrs. West started her career at the Naval Surface Warfare Center in Virginia in 1956. At the time, she was second black women working for the US Navy.
How does it work?
GPS is a navigation system using satellites, a receiver and algorithms to synchronize location, velocity and time data for air, sea and land travel. It is owned by the United States Space Force and operated by Mission Delta 31 (MD31). MD31 is the United States Space Force unit responsible for navigation warfare.
GPS does not require the user to transmit any data, and it operates independently of any telephone or Internet reception, though these technologies can enhance the usefulness of GPS positioning information. While the U.S. government created, controls, operates, and maintains the GPS system, it is freely accessible to anyone with a GPS receiver.
A GPS tracker receives radio frequency (RF) signals in the microwave band from an array of satellite transmitters orbiting the earth. Once a GPS tracker receives signals from four or more satellites, it determines its position through a series of time calculations and trilateration. The receiver relies on these precise and specific satellite signals to determine where it is in the world.
System and Components
GPS is made up of three different components, called segments, that work together to provide location information. The three segments of GPS are:
Space (satellites): The satellite system is a constellation of at least 31 satellites in six earth-centered orbital planes, each with four satellites, orbiting at 13,000 miles (20,000 km) above earth and traveling at a speed of 8,700 mph (14,000 km/h). The satellites transmit signals to users for geographical position and time of day. While only three satellites are needed to accurately resolve a location on earth’s surface, a fourth satellite is often used to correct the receiver’s clock error, to provide more accurate positioning.
Ground Control: The Control Segment is made up of earth-based monitoring stations, master control stations and ground antenna. Control activities include tracking and operating the satellites in space and monitoring transmissions. There are monitoring stations on almost every continent in the world, including North and South America, Africa, Europe, Asia and Australia.
User Equipment: Includes GPS receivers and transmitters, including items like watches, smartphones and telematic devices. In fleet operations, devices like telematics units or driver smartphones receive satellite signals and calculate exact positions to support dispatching and fleet safety. GPS receivers can be standalone/handheld devices for consumer use, or compact integrated circuits (ICs) or modules designed to be embedded into larger systems, devices, such as vehicles, sea going vessels etc.
As of 2025, 83 Global Positioning System navigation satellites have been built: 31 are launched and operational, 3 are in reserve or testing, 44 are retired, and 2 were lost during launch. GPS Satellite launches are on-going, as satellites need replacement after their useful lifespan. The next GPS satellite launch (GPS III SV0) is planned for late Jan 2026 from Cape Canaveral Space Force Station’s SLC-40 (launch pad) on a SpaceX Falcon 9 rocket.
The GPS satellite constellation requires a minimum of 24 operational satellites and allows for up to 32; typically, 31 are operational at any one time. After being launched, GPS satellites enter a period of testing before their signals are set to “Healthy”. During normal operations, certain signals may be set to “Unhealthy” to accommodate updates or testing.
After decommissioning, most GPS satellites become on-orbit spares and may be recommissioned if needed. Permanently retired satellites are sent to a higher, less congested disposal orbit where their fuel is vented, batteries are intentionally depleted and communication is switched off.
GPS uses three main civil radio frequency (RF) signal bands today: L1 at 1575.42 MHz, L2 at 1227.60 MHz, and L5 at 1176.45 MHz, each with different roles and signal structures.
L1 band - L1 is centered at 1575.42 MHz and is the original and most widely used GPS civil band. It carries the open C/A code, the encrypted P(Y) code, and newer signals such as L1C and M‑code, supporting legacy civil, modern civil, and military users.
The C/A code repeats every 1 millisecond and is used by civilian receivers to acquire and track satellites quickly. Each GPS satellite transmits a unique C/A code from a set of Gold codes, by modulating the code onto the L1 carrier frequency.
The P(Y) code is an encrypted code that repeats every 7 days and is used primarily for military precise positioning service (PPS) on both L1 and L2 carrier frequencies. Only authorized receivers with cryptographic keys can decrypt P(Y), providing higher precision and jam/spoof resistance.
L2 band -L2 is centered at 1227.60 MHz and was originally introduced mainly for military and precise applications. It carries P(Y) and the modern civil L2C signal, enabling dual‑frequency ionospheric correction (error correction for atmospheric affects) and higher‑precision positioning when combined with L1.
L5 band - L5 is centered at 1176.45 MHz, in the Aeronautical Radionavigation Service band reserved for safety‑of‑life operations. L5 has higher transmitted power, wider bandwidth, and longer codes than L1 C/A, improving multi-path rejection, interference resilience, and accuracy for applications like aviation approaches.
Jamming Counter Measures
Anti-jamming techniques use several technologies to detect, isolate, and reduce the impact of GPS interference. Solutions may be hardware-based, software-defined, or a hybrid of both. The common methods used to counter/prevent GPS jamming can be categorized as follows:
Antennas and related tools: Multi-element high quality antennas can help counter GPS jamming through specialized designs that detect and suppress interference while preserving weak satellite signals. These systems create directional “nulls” toward jammers, enabling reliable navigation in hostile environments. Examples are:
Controlled Reception Pattern Antennas (CRPAs) use multiple (4-16) antenna elements in an array to adaptively steer reception patterns. They generate nulls in the direction of jamming sources, canceling noise like covering an ear in a loud crowd, while focusing on legitimate GPS signals. Digital beam forming enhances this by processing signals to precisely nullify interference and boost signal-to-noise ratio.
What is a “null”? A null is “zone of silence” in the direction of the detected interference. This suppresses the jamming signal while still allowing legitimate satellite signals from other directions to be received. Null steering is effective in many scenarios but has limitations: it typically works best against a single interference source and cannot address all threats, such as spoofing or complex multi-directional jamming.
High-gain directional antennas: Focus on skyward GPS signals, rejecting ground-based jammers via narrow beam width and polarization matching.
Active anti-jam antennas: Embed filters like a Surface Acoustic Wave (SAW) filter to selectively pass GPS signals while rejecting unwanted interference, or ceramic to block out-of-band interference.
Signal-processing algorithms: Signal-processing algorithms help GPS receivers fight jamming by spotting and removing unwanted interference, much like tuning out loud static on a radio to hear a faint voice. These methods analyze the incoming signal to separate the weak GPS data from stronger jamming noise.
Algorithms first detect jamming through methods like energy detection, which scans for unusual power spikes, or cyclostationary analysis (to characterize signal properties), which identifies repeating interference patterns. Once spotted, adaptive notch filters create a null in the signal at the jamming frequency, blocking it without harming the GPS signal. For swept (chirp) jamming that shifts frequencies, high-resolution tools like Fast Orthogonal Search model the interference precisely so again it can be mulled out. Combined with hardware like directional antennas (see CRPAs above), with these systems, receivers stay operational where standard ones fail.
Integration with Inertial Navigation Systems: GPS receivers can be combined/ integrated with other Inertial Navigation Systems (INS) to provide resilient navigation during jamming. INS uses gyroscopes and accelerometers to track position, velocity, and orientation independently of GPS signals, so can bridge outages caused by interference. INS essentially provides a backup mechanism if the core GPS system becomes overwhelmed by jamming.
Wrapping up
Not trying to be a “Dougie Downer”, but here is a sobering thought….
There are no formal plans for a full replacement of GPS. The U.S. Space Force key efforts are focused on refinement and augmentation by enhancing satellites, ground control, and user equipment to improve accuracy, anti-jamming resilience, and signal capabilities. GPS III Satellites (generation III) are currently being deployed, and they will deliver 3X greater accuracy and 8X better anti-jamming. The GPS IIIF program, with launches starting in 2027, will deploy up to 22 satellites with 60X greater anti-jamming.
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