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Researchers from the University of Texas at Austin have identified an Israeli air base as a large source of widespread GPS disruptions affecting civilian airline navigation in the Middle East, reported The New York Times. 

The spoofing disruptions involve the transmission of manipulated GPS signals, which can cause airplane instruments to misread their location. Lead researchers Todd Humphreys and Zach Clements stated they are “highly confident” that Ein Shemer Airfield in northern Israel is the source of these attacks. The Israeli military declined The New York Times’ request for comment. 

The research team utilized data emitted by the spoofer and picked up by satellites in low-Earth orbit (LEO) to determine its location. They then confirmed their calculations using ground data collected in Israel.  

Spoofing, along with GPS jamming, has significantly increased over the past three years, especially near war zones such as Ukraine and Gaza. In these areas, militaries interfere with navigation signals to redirect aerial attacks. 

The Middle East has emerged as a hotspot for GPS spoofing, with The New York Times reporting that a separate analysis estimates more than 50,000 flights have been affected in the region in 2024 alone. Researchers from SkAI Data Services and the Zurich University of Applied Sciences, analyzeding data from the OpenSky Network and, found that these attacks have led pilots to mistakenly believe they were above airports in Beirut or Cairo. 

Swiss International Air Lines told The New York TimesNYT that their flights are spoofed “almost every day over the Middle East.” 

The issue extends beyond the region, with Estonia and other Baltic nations having blamed Russia for disrupting signals in their airspaces. Additionally, in April 2024, Finnair temporarily suspended flights to Tartu, Estonia, amid the rise of GPS jamming in the region affecting civilian air travel.  

The attacks have not led to significant safety risks as pilots can use alternative navigation methods. However, they do raise concerns. 

Jeremy Bennington, vice president of Spirent Communications, told The New York Times, “Losing GPS is not going to cause airplanes to fall out of the sky. But I also don’t want to deny the fact that we are removing layers of safety.” 

The spoofing attacks may cause false alerts about planes being too close to the ground, leading to navigation confusion and possibly compromising flight safety. 

As these disruptions continue to affect large areas far from active conflict zones, the aviation industry and international authorities are under increasing pressure to address this emerging threat to air travel security. 

<p>The post Israeli air base identified as alleged source of GPS disruptions in Mideast first appeared on GPS World.</p>

The ongoing conflict between Hamas and Israel, along with the unrest in various universities across the United States in support of Gaza Palestinians, and the continued aggression by the Houthi rebels in Yemen against shipping, are impacting several aspects of our lives, including the rising cost of gasoline.

Since the United States began seeking out Houthi strongholds, it is now being reported that another MQ-9 Reaper drone has been shot down – making an apparent total of five such expensive U.S. UAVs lost over and around Yemen, according to US military reports.

Screenshot of a Houthi-released video of the downing of the MQ-9 Reaper drone (Photo: UAS Vision)

At $30 million each, compared to about $2 million for a surface-to-air missile, the Houthis are apparently ahead on cost. With a 50,000 ft ceiling, the Reaper is capable of avoiding short-range surface-to-air missiles. However, more visual or infra-red (IR) low-level detail may have been sought on this mission. In response, the U.S. military reported the downing of five Houthi UAVs over the Red Sea.

According to a Defense Intelligence Agency (DIA) report, Iran is supplying the Houthis with attack UAVs and longer-range missiles, which are often, if not always, re-assembled, repainted and re-named locally. The DIA said that one of the favorite Kamikaze UAVs used is the Iranian Shahed-136/Houthi Waid-2, which is reported to have a range of almost 1,600 miles. Neither side has yet acknowledged which drones were brought down by the United States.

Shahed-136 (Photo: bbsferrari / iStock / Getty Images Plus / Getty Images)

However, around the same time, it was reported that perhaps two Houthi missiles hit the MV Andromeda Star oil tanker with reportedly little damage — no casualties were reported on the ship as it continued towards its destination Vadinar, India. Another ship, the MV Maisha, avoided a third missile. The missile landed nearby in the water, but the vessel put some distance between itself and the MV Andromeda, continuing safely.
The US/UK forces operating in the Red Sea have countered the more than 100 Houthi attacks on shipping with several airborne strikes on Houthi facilities. This renewed Houthi action over the weekend is thought to have been possible because they were restocked with weapons following the US/UK airstrikes, which slowed their attacks on shipping.

Hence the renewed threat to oil tanker traffic in the Red Sea has raised the already high threat level, and increased oil and gas prices at the pump are one of the consequences.

Meanwhile, Pakistan has bought 10 additional Chinese Caihong-4, which reportedly look and perform very similarly to the MQ-9 Reaper.

Caihong-4 looks very similar to the General Atomics MQ-9 Reaper
(Photo: OE Data Integration Network (ODIN))

The CH-4 can be used for both attack and reconnaissance. It features a flight endurance of 30 to 40 hours, a range of 2,200 to 3,100 miles and can carry up to six weapons.

This brings Pakistan’s complement to 20 CH-4 UAVs. The new purchase may be to offset India’s purchase of 31 General Atomics MQ-9s, which is included in a huge, recently approved $3.99 billion weapons purchase from the United States. The two countries continue to feud over the contested Kashmir region.

AeroVironment (AV) has developed an add-on for fielded Puma class hand-launched reconnaissance UAVs, which brings autonomy and machine-learning to a worldwide, mostly military fleet of thousands of air vehicles. Referred to as the Autonomy Retrofit Kit (ARK), with AVACORE software, the new update allows operators to command and control one or more vehicles autonomously. This provides computer vision capabilities and enables connection to a distributed, mobile comms network to access data for several separated operating groups.

ARK retrofit kit for Puma 3AE and LE UAVs (Photo: AV)

According to AV, autonomous operating tasking is possible when communications are jammed and the UAV is then still able to execute its mission without manual input. Updated computer vision allows finding, classifying, positioning and daylight or nighttime tracking of objects such as people, vehicles, aircraft and ships. AVACORE includes several software interfaces for different autopilots, sensors and radios to provide integration flexibility.

A neat way to provide significantly enhanced capability for already fielded airborne vehicles when they have some downtime.

Finally, we have a short introduction to a new transport UAV being put together by a California company called MightyFly. The company is led by a woman who was highly instrumental in the success of the flight controls for the Zipline UAV, which is still blazing drone delivery trails overseas and now in North America — with more than one million deliveries. With advisory input from a retired FedEx exec, the team at MightyFly seems well on their way with both a Federal Aviation Administration (FAA) approved Part 135 application and a 20 mile ‘point-to-point’ flight corridor approval for test flights.

Cento gen 3 cargo drone (Photo: MightyFly)

The MF-100 prototype made its first flight and demonstration delivery in April 2021, while the third-generation Cento flew for the first time in December 2022. Cento has a 6’ x 1’ x 1’ cargo hold that can accommodate 96 small USPS packages, weighing up to 100lb and Cento and later models are expected to have a range of 600 miles at up to 150 mph. While their UAVs are currently all-electric, the plan is to add a gas/rotary engine to charge batteries to achieve this forecast range for the drone.

MightyFly has significant support from the U.S. Air Force Agility Prime program and the Air Mobility Command, who continue to invest in autonomous cargo developments as an alternative to leasing helicopters to transport parts, medical supplies and more. MightyFly came up with an auto-loading capability, which resolves the issue of a potentially changing weight and balance of a last-mile cargo drone.

<p>The post Unmanned systems updates first appeared on GPS World.</p>

Photo: Oren Kfir / iStock / Getty Images Plus / Getty Images

On April 4, residents of Tel Aviv, Israel, noticed that map applications on their phones such as Waze, Google Maps and the taxi pickup app Gett were placing them in Lebanon’s capital, Beirut, 130 miles to the north. Cab drivers could not navigate and food-delivery apps were temporarily out of service, reported The Wall Street Journal.

The spoofing was a result of the Israeli military tampering GPS signals to brace for possible retaliation by Iran or one of its allied militias after a suspected Israeli airstrike on an Iranian diplomatic building in Syria. The attack killed a senior Iranian general, Mohammad Reza Zahedi, and six other military officials. It has marked an escalation of the yearslong conflict between Israel and Iran.

According to WSJ, analysts say a direct Iranian strike on Israel is unlikely. However, one day after Israel drafted reservists to boost air defenses, the Israeli military said it would pause all leave for combat units “in accordance with the situational assessment.”

Israel has withdrawn some of its ambassadors and evacuated its embassies in multiple locations. With tensions and uncertainty rising, several Israeli municipalities near Tel Aviv put out announcements to calm residents and refresh guidance for emergencies.

According to the Israeli military, the GPS spoofing — which can be used to confuse targeting systems for military weapons — was part of an effort to protect the country. “Today we initiated GPS disruption in order to neutralize threats,” said Israeli military spokesman Daniel Hagari. “We are aware that this disruption causes discomfort, but this is an essential and necessary tool in our defense capabilities.”

Israel has ramped up GPS jamming and spoofing since the start of its war with Hamas in early October 2023, but mainly in the north of the country, where the Iranian-backed Hezbollah militia has rockets to strike Israeli towns and military bases, according to Reuters.

The military has scrambled signals in southern Israel, mainly around the city of Eilat, the target of missile and UAV attacks by Iranian-backed Yemeni and Iraqi militias, according to Yigal Unna, former director general of the Israel National Cyber Directorate.

The GPS disruptions have intensified since the most recent strike and have spread to central Israel where a local taxi driver shared that his map application had located him at the Rafic Hariri International Airport in Beirut. In the south of the country, and in Jerusalem and the occupied Palestinian West Bank, GPS devices placed users in Cairo, residents told WSJ.

Mohammad Abdelhalim, founder of the Palestinian navigation app Doroob, said that signal interruptions have occurred regularly on various platforms that rely on GPS since the Oct. 7 Hamas-led attacks on Israel, ranging from a few minutes to several hours at a time.

Spoofing can pose risks beyond being a nuisance for citizens. Distorting signals can create challenges for civilian and commercial planes that use GPS signals for navigation. Spoofing can also throw guided missiles off their trajectory, which poses unpredictable risks to civilians.

The ramifications of the widening GPS blackouts remain unclear. Beyond the hassles for civilian drivers, there are safety concerns for emergency responders and commercial transit unable to reliably track locations.

The recent spoofing in Tel Aviv is one of countless reminders that the country’s active military actions are only miles away and can have cascading effects on aspects of daily life.

<p>The post GPS disruptions in Tel Aviv as Israel braces for possible Iranian attacks first appeared on GPS World.</p>

Image: NiseriN/ iStock / Getty Images Plus/ Getty Images

Three U.S. service members were killed and dozens wounded during a UAV attack on U.S. forces stationed in northeastern Jordan near the Syrian border, President Joe Biden and U.S. officials said on January 28.

Biden blamed Iran-backed groups for the attack, the first deadly strike against U.S. forces since the Israel-Hamas war erupted in October 2023 and sent shock waves throughout the Middle East.

“While we are still gathering the facts of this attack, we know it was carried out by radical Iran-backed militant groups operating in Syria and Iraq,” Biden said in a statement.

At least 34 personnel were being evaluated for possible traumatic brain injury, a U.S. official told Reuters, speaking on the condition of anonymity. Two officials said some wounded U.S. forces were medically evacuated from the base for further treatment.

The Islamic Resistance in Iraq – an umbrella organization of Iran-backed militant groups — claimed attacks on three bases, including one on the Jordan-Syria border.

The attack is a major escalation in the already tense situation in the Middle East, where war broke out in Gaza after the Palestinian Islamist group Hamas attacked Israel on October 7, killing 1,200 people. Israel’s subsequent assault on Gaza has killed more than 26,000 Palestinians as of January 2024, according to the local health ministry.

Since then, U.S. forces have come under attack more than 150 times by Iran-backed groups in Iraq and Syria. U.S. warships have also been fired at by Iran-backed Houthi forces in Yemen, who are regularly attacking commercial ships passing through Red Sea waters off Yemen’s coast.

While the United States has maintained an official line that Washington is not at war in the region, it has been retaliating against the Iran-backed groups in Iraq and Syria and carrying out strikes against Yemen’s Houthi military capabilities.

Referring to the fallen soldiers, in his statement released by the White House Biden said: “We will carry on their commitment to fight terrorism. And have no doubt — we will hold all those responsible to account at a time and in a manner of our choosing.”

<p>The post 3 US troops killed, up to 34 injured in Jordan UAV strike linked to Iran first appeared on GPS World.</p>

Image: guvendemir/ E+/Getty Images

Electronic warfare in the Middle East and Ukraine is affecting air travel far beyond the battlefields, unnerving pilots and revealing unintended consequences of a tactic that experts believe will become more widespread, reported The New York Times.  

Planes are losing satellite signals, flights have been diverted and pilots have received false location reports or inaccurate warnings that they were flying close to terrain, according to European Union safety regulators and an internal airline memo viewed by The New York Times. The Federal Aviation Administration (FAA) has also warned pilots about GPS jamming in the Middle East. 

Following Russia’s invasion of Ukraine in early 2022, radio frequency interference only continues to increase across the Middle East as of autumn 2023. These interferences can involve jamming GNSS signals to obstruct or block them using noise, or mimicking signals to trick GNSS receivers into picking up counterfeit satellite signals, known as spoofing.  

Aircraft systems have been unable to detect GPS spoofing and ultimately correct for it. According to Opsgroup, an organization that monitors changes and risks in the aviation industry, one Embraer jet bound for Dubai nearly veered into Iranian airspace in September before the pilots figured out the plane was chasing a false signal. 

“We only realized there was an issue because the autopilot started turning to the left and right, so it was obvious that something was wrong,” crew members reported to Opsgroup. 

Issues arise 

With the rise of electronic warfare, the strain on aviation could be a sign of more serious economic and security issues.  

The U.S. government calls GNSS signals “an invisible utility.” Smartphones, cars, stock exchanges, data centers and countless industries rely on them for time, navigation or both. Similar systems exist around the world, such as Galileo in Europe, Glonass in Russia, QZSS in Japan, NavIC in India and BeiDou in China. One study from Britain said a five-day disruption of satellite signals could cost the country $6.3 billion. 

Minor interference with GPS signals is fairly common. GPS jamming devices, while illegal to use, are inexpensive and easy to obtain from vendors on the internet. Governments, too, have been more willing to overtly interfere with signals as a tactic in electronic warfare. 

It is not always possible to distinguish jamming from spoofing, or to determine who is behind the interference. Israel said in mid-October it had restricted GPS in the region and had warned pilots not to rely on satellite navigation systems for landing.  

Russian interference is well-documented. A 2019 report by the Washington-based analytical nonprofit group C4ADS showed extensive spoofing from a Russian-controlled air base in Syria. Reports also indicated that, when Russian President, Vladimir Putin, traveled to remote locations or Russian-occupied Crimea, he was flanked by mobile GPS-spoofing technology. 

Russia has disrupted GPS signals to misdirect Ukrainian UAVs and throw precision-guided shells off their targets. Ukraine also jams Russian receivers but lacks the same level of sophistication.  

Jamming is common in conflict zones. Spoofing, until recently, was considered rare.   

The interference has been felt up to 190 miles away from battlefields and “appears to go well beyond simple military mission effectiveness,” according to Eurocontrol, Europe’s primary air-traffic-control manager. The worst-affected regions include the aerial space above the Black Sea area from Turkey to Azerbaijan; the Mediterranean Sea extending from Cyprus to Libya; the Baltic Sea near Poland and Latvia; and the Arctic near Finland and Norway. 

Airbus said it recorded nearly 50,000 interference events on its aircraft last year, more than four times as many as the year before. This came on top of an over twentyfold jump in radio-interference events from 2017 to 2018, as recorded by a voluntary incident reporting system run by Eurocontrol. Eurocontrol said the increased jamming since 2018 was most likely meant to interfere with battlefield UAVs. 

In the Middle East, there have been reports of false signals telling pilots their aircraft were directly above the airport in Tel Aviv despite being far away. Opsgroup said it had received around 50 similar reports. In some cases, onboard equipment showed that planes were approaching airports in Baghdad, Cairo or Beirut, Lebanon, when they were not. 

Looking ahead 

Spoofing is hard to distinguish because the signal appears legitimate. Only Europe’s Galileo incorporates an authentication system that can verify when a signal is from its satellites. Galileo, which currently is the most accurate and precise navigation satellite system, plans to introduce an even stronger level of authentication, according to the European Commission. 

But even Galileo’s authentication cannot protect against one of the most dreaded types of spoofing, known as “meaconing.” In a meaconing attack, a spoofer would record satellite signals, and then rebroadcast them with an amplification or a delay. Experts have not publicly confirmed any meaconing attacks in the Middle East. 

Opsgroup said the latest events should prompt manufacturers to re-examine the integration of satellite signals in aircraft electronics, known as avionics, without a safeguard that can identify false signals.

In this environment of intentional GPS jamming and spoofing, Israel has produced a leading anti-jam technology company, InfiniDome, located in Caesarea. According to co-founder Omer Sharar, the company has been working to defend GPS signals for more than seven years and has also seen the rise of devices to jam the GPS L1 frequency that anyone can buy online for $100.   

Gpsdome-1 (left) protects GPS L1. GPSdome-2 (right) protects GPS L1/L2 or GPS L1/GLONASS L1. (Image: InfiniDome)

Most readily available jammer electronics only output interference disrupting GPS L1, which is commonly installed for vehicle tracking and UAV guidance. InfiniDome says it has successfully protected trucking, UAV operations and others in Israel and around the world with its Infinidome GPSdome-1 and GPSdome-2 anti-jam products. 

It is clear the conflict’s repercussions extend well beyond the battlefield, highlighting the critical need for security assessments or alternative PNT systems to protect civilians. While there is going to be a significant impact on commercial airline travel to and from Israel while hostilities continue, there is hope for a possible long-term solution for the intense jamming that has plagued the region for years.  

<p>The post Beyond the frontlines: The far-reaching effects of electronic warfare first appeared on GPS World.</p>

One of the things you can be sure of in the Ukraine-Russia war is that one side or the other is jamming the other’s communications and sat-nav guidance systems. An apparent consequence is that there is likely some “spill-over” to adjacent areas. For Israel, however, it looks like it’s more directed jamming rather than incidental.

Israel GPS jamming. (Image: GPS Jam.org)

In this environment of intentional GPS jamming, it’s not surprising that Israel has produced a leading anti-jam technology company, called InfiniDome, in Caesarea (between Haifa and Tel-Aviv). According to co-founder Omer Sharar, the company has been working to defend GPS signals for more than seven years and has also seen the rise of devices to jam the GPS L1 frequency that anyone can buy online for $100.  

 Just as Ukraine is throwing explosive cardboard UAVs with little cost at Russian occupying forces, a few carefully placed low-cost jammers could inflict serious damage on a country’s navigation capabilities. 

 However, a 2019 presentation by Todd Humphreys identified the source of interference and spoofing at that time, a Russian high-power jammer located at a Russian base in Syria. 

Humphreys used instrumentation on the International Space Station (ISS) to gather data on the directed interference but concluded that the jamming in Israel could be a consequence of Russia’s efforts to protect its troops in Syria from UAV attacks. The Russian Khmeimim Air Base is on the Mediterranean coast and attacks are thought to come from rebels within Syria.

With the current GPS jamming out of Syria, most commercial aircraft traffic flying into Ben Gurion International Airport is significantly affected as flights cross from over the coast from the Mediterranean. Longer flight tracks deeper southeast into Israel are necessary, probably relying on VOR and DME ground station waypoints before turning back northwest to capture the instrument landing system (ILS) into the airport. This costs time and fuel and causes aircraft to overfly settlements where noise can be a real problem.

Most readily available jammer electronics only output interference disrupting GPS L1, which is most commonly installed for vehicle tracking and UAV guidance. InfiniDome has successfully protected trucking, UAV operations and others in Israel and around the world with its Infinidome GPSdome-1 and GPSdome-2 anti-jam products.

Gpsdome-1 (left) protects GPS L1. GPSdome-2 (right) protects GPS L1/L2 or GPS L1/GLONASS L1.

Two antennas 10 cm to 25 cm apart enable GPSDome-1 algorithms to detect and null out a GPS L1 jammer. GPSDome-2 accommodates up to four antennas and can null up to three directional signals on both GPS L1 and L2 or GPS L1 and GLONASS L1. 

InfiniDome is currently working with an aerospace company to integrate its anti-jam technology with airborne inertial/GPS and qualify the integrated system for use in civil aviation, with the objective of maintaining max 3% drift when fully jammed. This will introduce certified anti-jam technology into civil aviation use — something that will provide some jamming protection, which airlines desperately need going forward. In addition, other high-end UAV manufacturers are potential customers for this new system. 

While the ongoing conflict and the devastating loss of life is forefront as each day of the war passes, these anti-jam solutions may ultimately help solve signal degradation problems. While there is going to be a significant impact on commercial airline travel to and from Israel while hostilities continue, we can maybe see the way to a possible long-term solution for the intense jamming from which the region has suffered for many years. 

<p>The post GPS jamming in Israel first appeared on GPS World.</p>

Image: GPSJam.org

Israel has declared war on the Palestinian militant group  Hamas after it carried out an unprecedented attack by air, sea and land on October 7, 2023.

The large-scale surprise attack has left more than 1,200 dead in Israel, said Israel Defense Forces spokesperson Lt. Col. Jonathan Conricus in an update on October 11. It has since prompted retaliatory Israeli airstrikes on Gaza that have killed more than 1,055 people.

During the ongoing conflict between Israel and Hamas, the Middle East is witnessing a significant shift in the patterns of GPS interference, with data showing an increase in disruptions compared to just a week prior, according to Defence and Security Middle East.

Reports have surfaced indicating Hamas has actively jammed Israeli communication systems during the initial stages of the conflict. This strategic move highlights the increase of jamming GPS and communication networks in modern warfare scenarios, where precision and coordination are imperative.

Positioning, navigation and timing (PNT) services play a role in a variety of military systems and civil technologies. These services not only guide precision warfare, but also facilitate efficient transportation, communication and various civilian applications.

The Middle East has a history of being a focal point for jamming and spoofing activities, impacting not only security but also regional stability and even commercial flights.

For example, there have been recent reports of recurring interference allegedly caused by Russian systems in Syria, which frequently disrupts air traffic at Tel Aviv’s Ben Gurion airport. Regulatory bodies, such as the Federal Aviation Administration, the European Union Aviation Safety Agency, and Israel’s aviation authority, advised airlines to exercise caution when operating in the airspace of the region. Multiple airlines have now canceled or suspended flights.

With airlines reducing services and regulatory bodies advising caution, the conflict’s repercussions extend well beyond the battlefield, highlighting the critical need for security assessments or alternative PNT systems to protect civilians.  

<p>The post GPS jamming increases amid Israel Hamas conflict first appeared on GPS World.</p>

An approach for ground vehicles using carrier-phase and inertial measurement data

The combination of easily accessible low-cost GNSS spoofers and the emergence of increasingly automated GNSS-reliant ground vehicles prompts a need for fast and reliable GNSS spoofing detection. To underscore this point, Regulus Cyber, an Israeli cybersecurity company, recently spoofed a Tesla Model 3 on autopilot mode, causing the vehicle to suddenly slow and unexpectedly veer off the main road.

Among GNSS signal authentication techniques, signal-quality monitoring (SQM) and multi-antenna could be considered for implementation on ground vehicles. However, SQM tends to perform poorly on dynamic platforms in urban areas where strong multipath and in-band noise are common, and multi-antenna spoofing detection techniques, while effective, are disfavored by automotive manufacturers seeking to reduce vehicle cost and aerodynamic drag. Thus, there is a need for a single-antenna GNSS spoofing detection technique that performs well on ground vehicles, despite the adverse signal-propagation conditions in an urban environment.

In a concurrent trend, increasingly automated ground vehicles demand ever-stricter lateral positioning to ensure safety of operation. An influential study calls for lateral positioning better than 20 centimeters on freeways and better than 10 centimeters on local streets (both at a 95% probability level). Such stringent requirements can be met by referencing lidar and camera measurements to a local high-definition map, but poor weather (heavy rain, dense fog or snowy whiteout) can render this technique unavailable.

On the other hand, progress in precise (decimeter-level) GNSS-based ground vehicle positioning, which is impervious to poor weather, has demonstrated surprisingly high (above 97%) solution availability in urban areas. This technique is based on carrier-phase differential GNSS (CDGNSS) positioning, which exploits GNSS carrier-phase measurements having millimeter-level precision but integer-wavelength ambiguities.

Key to our promising results is the tight coupling of CDGNSS and inertial measurement unit (IMU) data, without which high-accuracy CDGNSS solution availability is significantly reduced due to pervasive signal blockage and multipath in urban areas. Tight coupling brings millimeter-precise GNSS carrier-phase measurements into correspondence with high-sensitivity and high-frequency inertial sensing. Our particular estimation architecture incorporates inertial sensing via model replacement, in which the estimator’s propagation step relies on bias-compensated acceleration and angular rate measurements from the IMU instead of a vehicle dynamics model.

As a consequence, at each measurement update, an a priori antenna position is available whose delta from the previous measurement update accounts for all vehicle motion sensed by the IMU, including small-amplitude high-frequency motion caused by road irregularities. Remarkably, when tracking authentic GNSS signals in a clean (open-sky) environment, the GNSS carrier-phase predicted by the a priori antenna position and the actual measured carrier phase agree to within millimeters.

The research described in this article pursues a novel GNSS spoofing-detection technique based on a simple but consequential observation: it is practically impossible for a spoofer to create a false ensemble of GNSS signals whose carrier-phase variations, when received through the antenna of a target ground vehicle, track the phase values predicted by inertial sensing. In other words, antenna motion caused by factors such as road irregularities or rapid braking or steering is sensed with high fidelity by an onboard IMU but is unpredictable at the sub-centimeter-level by a would-be spoofer.

Therefore, the differences between IMU-predicted and measured carrier-phase values offer the basis for an exquisitely sensitive GNSS spoofing-detection statistic. What is more, such carrier-phase fixed-ambiguity residual cost is generated as a byproduct of tightly coupled inertial-CDGNSS vehicle position estimation.

Two difficulties complicate the use of fixed-ambiguity residual cost for spoofing detection. First is the integer-ambiguous nature of the carrier-phase measurement, which causes the post-integer-fix residual cost to equal not the difference between the measured and predicted carrier phases (as would be the case for a typical residual), but rather modulo an integer number of carrier wavelengths. Such integer folding complicates development of a probability distribution for a detection test statistic based on carrier-phase fixed-ambiguity residual cost.

Second, the severe signal multipath conditions in urban areas create thick tails in any detection statistic based on carrier-phase measurements. Setting a detection threshold high enough to avoid false spoofing alarms caused by mere multipath could render the detection test insensitive to dangerous forms of spoofing. Reducing false alarms by accurately modeling the effect of a particular urban multipath environment on the detection statistic would be a Sisyphean undertaking, requiring exceptionally accurate up-to-date 3D models of the urban landscape, including materials properties.

Our work takes an empirical approach to these difficulties. It does not attempt to develop a theoretical model to delineate the effects of integer folding or multipath on its proposed carrier-phase fixed-ambiguity residual cost-based detection statistic. Rather, it develops null-hypothesis empirical distributions for the statistic in both shallow and deep urban areas, and uses these distributions to demonstrate that high-sensitivity spoofing detection is possible despite integer folding and urban multipath.

<p>The post GNSS Spoofing Detection: Guard against automated ground vehicle attacks first appeared on GPS World.</p>