Future Fighting Without GPS?

“We assume that in the next war, our GPS-based systems won’t be functioning,” says a senior military figure. So how is Israel preparing for this eventuality?

“We assume that in the next war, our GPS-based systems won’t be functioning,” says a senior military figure. So how is Israel preparing for this eventuality? “By developing technological solutions to GPS jammers, and basing our future weapons systems on other navigational methods: atomic clocks, quantum navigation, and scene-matching guidance systems, to name just a few.”

In March it finally happened. The United States and South Korea began a round of joint military exercises code-named “Key Resolve/Foal Eagle” that involved 12,800 American soldiers and 200,000 South Korean troops.

The soldiers faced a scenario in which, precipitated by the unsuccessful ascension of Kim Jong Un following the death of his father and long-time North Korean leader Kim Jong Il, a military conflict had erupted between both sides of the peninsula.

However, towards the end of the exercise GPS systems started to fail, particularly in areas such as Seoul and Paju. Most affected were US Tomahawk cruise missiles, as well as Joint Direct Attack Munition (JDAM) kits, meant to turn gravity bombs into precision satellite-guided weapons.

According to South Korean intelligence, North Korea was able to jam the GPS signal with two different systems. The first was with a vehicle-mounted device Pyongyang had procured from Russia in the early 2000s, believed to be capable of jamming GPS signals from 50 to 100 kilometers (30 to 60 miles) away.

The second was a spinoff of the Russian system manufactured domestically in North Korea, which is believed to have similar capabilities but costs less on the open market. South Korean intelligence has claimed that in early 2010, North Korea purchased a new 24-Watt jammer from Russia – capable of jamming GPS reception within a 400 kilometer radius, which basically covers the entire Korean Peninsula.

The event did not go unnoticed in Israel, which has for years feared but simultaneously prepared for the possibility that—in a future conflict with Hezbollah in Lebanon, Hamas in the Gaza Strip, Syria or Iran—its GPS-guided weapons will fail. The IDF has taken into consideration the possibility that North Korea has sold its GPS jamming system to countries in the Middle East including Lebanon, Syria, and Iran.

GPS jamming capabilities have been a taboo subject within the Israeli defense establishment and IDF for years, with officers dissuaded from even discussing the potential vulnerability. But as the possibility of a new conflict looms on the horizon, there is no ignoring the likelihood of Israeli bombs being rendered satellite-less in a future war.

“This is a concern and we are preparing for it,” was all that a senior IDF officer was willing to say, when recently asked about the threat.

So what is GPS?

It is an acronym for “Global Positioning Satellite.” The US Department of Defense began to develop GPS technologies in the 1970s and they became operational in the mid-90s. The program presently consists of 32 American satellites that provide autonomous positioning with global coverage, allowing receivers to determine their location to within a few meters.

The satellites revolve around the earth at an altitude of 20,000 kilometers and each is fitted with an atomic clock so they are all synchronized to the same time. Each satellite completes one orbit roughly every 12 hours.

Over the years, GPS has become an integral part of life and not just in the military—it is also used by ships to navigate courses at sea, by cars to travel on land, and by the civil aviation industry.

In the military, GPS has become somewhat taken for granted. The IDF’s foray into the world of GPS began in 2000 when it became the first foreign customer outside the United States to receive JDAM kits. The IDF proceeded to fit the kits onto 2,000-pound MK-84 bombs, thus turning them into precision satellite-guided weapons.

Over the years, the air force has become increasingly dependent on JDAMs, which enable pilots to release bombs from a standoff position, without the need for flying directly over targets where surface-to-air missiles could endanger them.

An example of JDAM’s importance in air force operations came during Operation “Cast Lead” in the Gaza Strip (December 2008-January 2009) when 81 percent of the munitions dropped by the IAF were smart bombs—the largest percentage of precision guided weapons used in a conflict in world history.

But with this reliance comes inherent risks, as jamming systems with the proven ability to block GPS-guided weapons become more readily available on the open market.

In addition, Israel has always been concerned that the US could one day shut down its GPS satellites in order to prevent Israel from engaging in a war that the administration in Washington would not support.

“In a future war, our enemies will have the ability to jam GPS guided weapons,” a former senior IDF officer said. “It’s a challenge that has always been at the top of our priority list.” In Israel, the company responsible for defending Israeli GPS systems against jammers is Rokar, a Jerusalem-based subsidiary of BAE Systems.

Rokar’s product line includes a family of Satellite Navigation Immune Receivers (SNIR), which makes GPS systems unsusceptible to jamming. SNIR can be found in aircraft, tanks, weapons, and naval vessels. It uses advanced algorithms, signal processing, and anti-jamming technologies to support navigation systems in a multiple-jammer environment.

Nir Lavi, director of marketing and business development at Rokar, warned that a small suitcase, fitted with a relatively simple jammer, could shut down GPS navigation systems for hundreds of kilometers. “If a country doesn’t take any precautions to protect GPS then it will be in trouble, since jammers are something that will likely be on a future battlefield,” acknowledged Lavi.

Consider navigation for ground forces. In today’s IDF, the tanks, armored personnel carriers, and artillery howitzers are all connected to the Ground Force Command’s Digital Army Program (DAP), which tracks the positioning of all Israeli units in addition to the positions of enemy forces. DAP also helps to improve units’ maneuverability and can lead them to the location of their target.

Former Israeli Air Force (IAF) commander, Major General (Res.) Eytan Ben Eliyahu, told IsraelDefense that, while GPS satellites could possibly be shut down by the US or be jammed by an enemy, the benefits from having invested in the system far outweigh the risks.

He noted that, “The need for a backup system was always important, but the possibility of interference has always been a problem for every military system; air defense missiles threaten fighters and radios can be blocked. Nothing is foolproof but these vulnerabilities do not justify not using the systems.”

Ben Eliyahu served as IAF commander from 1996 until 2000, during which time the Ministry of Defense signed a historic deal to purchase its first batch of JDAM kits. In 2000, several months after he retired, the kits arrived and provided the air force with the ability to launch missiles from standoff positions, day or night, and in all-weather conditions.

“I pushed very hard for the JDAMs since I realized they were going to provide us with new capabilities that would change the way we operate,” he said. “There are potential problems but, when weighing the risks alongside the benefits, it is definitely worth relying on such systems.”

Is it really that easy to jam GPS?

The short answer is “yes.” Even though jammers are illegal to buy and use in countries like the United States, this doesn’t stop some websites from offering them for as low as $45 with free worldwide shipping. “There’s no real protection against jamming,” says David Last, former president of the Royal Institute of Navigation and GPS consultant to the British government.

Referring specifically to a future war between Israel and Hezbollah, Last claimed that theoretically, Hezbollah could place a special radio transmitter on an elevated surface—like a tall mountain in southern Lebanon—and potentially block Israeli GPS within a radius of several kilometers.

“It takes so little jamming capabilities to take out GPS and jam a very considerable area. All you need is an easily portable radio transmitter and if you set it up on an elevated location, you can cover a large area.”

There are, of course, different ways to jam GPS. For example, one way is to simply block the GPS receiver inside a weapon system, by preventing it from hooking up to the satellite. A more sophisticated method is called “spoofing,” which tricks the weapon’s GPS navigation system into thinking that it’s flying towards the target, when in reality it’s been “spoofed” and is headed somewhere else.

Last concedes that, although general awareness has increased in recent years regarding the danger of potential breakdowns in GPS systems—especially in civil aviation and maritime transport—the threat is growing.

While the US is also working on a new generation of satellites—called GPS III—that are purportedly immune to jamming, Last says that any responsible military will have to develop alternative systems so as not to be “blinded” in a future war. “Some fairly advanced technologies are in use on aircraft and missiles to minimize the effect, but you must have backup systems to survive,” he warns.

What happens if GPS doesn’t work? How will the IDF get its forces and weapons where they need to go?

If GPS is unavailable, Israel could potentially link up with alternative satellite navigation systems that will be operational in the near future.

The European Union, for example, is developing its own satellite navigation system called “Galileo” and the Russians are adding satellites to their GLONASS program to achieve global coverage. Some Israeli navigation systems already come installed with the dual ability to connect to either the US or Russian systems.

Another possibility for Israel is to utilize its expertise in developing micro and mini-satellites to launch a cluster of satellites over an area of operations, which could ultimately provide a backup navigation network to GPS. Rafael is developing a capability to launch microsatellites from F-15s.

Inertial Navigation

Due to the risk of jamming, one of the IDF’s requirements has been to develop alternatives for GPS weapons and navigation systems. However, on the bottom line, it seems that satellites are apparently not trusted in Israel, and the obvious tendency is to return to the navigation methods of old, primarily inertial navigation.

Inertial Navigation Systems (INS) utilize computers and motion sensors in order to calculate a position, based on direction and movement speed, without the need for any external reference point. In other words, the system knows its initial coordinates, and calculates the position or a target according to continuous assessments of time, speed, and momentum.

Despite the fact that INS were always required in places where there was no GPS reception (in submarines cruising underwater, for example), there was a tendency to neglect their development during the 1990s and even more recently. This was done out of a perception that GPS systems were nearly infallible. However, this is not the situation today, as several companies are developing alternative advanced technologies in Israel.

In general, an INS necessitates six sensors—three linear accelerometers, which examine the motion in all spatial dimensions, and three rotation gauges (gyros).

Some of the Israeli weapon systems (such as mini UAVs or kits that pinpoint the position of soldiers in the framework of Elbit Systems’ “Future Infantry Program”) are based on chips that utilize MEMS (Micro Electro Mechanical System) technology from cheap mass production lines in global factories. These chips represent an alternative to the advanced sensors and can even be found in iPhones. However, they aren’t considered reliable enough and are not impervious to the conditions prevalent within most military systems.

Due to the importance of the subject, most of the large defense companies possess in-house capabilities for developing military-purposed inertial navigation systems. At Israel Aerospace Industries (IAI), the accelerometers are developed in the Tamam factory; at Elbit Systems, they’re developed in El-Op. Rafael, Israel Military Industries (IMI) and Rada operate in the field as well.

Standard accelerometers are based on a tiny pendulum that can calculate its acceleration at any given moment based on its motion. The pendulum deduces the necessary data needed for a constant position calculation – direction and speed.

Israel is considered a global leader in the development of optics-based gyroscopic technologies. These are technologies which, besides Israel, exist only in the United States, Germany, France, and China.

One of the technologies is based on laser beams that move within a system of mirrors, and another based on light beams rotating circularly in a fiber optic system. The more the scope of the light’s rotation increases, the greater the attainable level of accuracy, as is required for long-range arms systems.

The Jerusalem-based El Cielo, which belongs to the Aeronautics group, is also developing such sensors for civilian inertial navigation systems. These are purposed for use in the mining industry and for discovering oil and gas fields at sea (where GPS signals can’t be received).

The sensors can’t allow for spatial orientation, unless they are part of a fastened navigation system, which includes a powerful inertial measurement unit capable of translating data into precise coordinates.

Inertial navigation systems are generally considered less precise and are more costly than GPS systems. A standard INS seeks to reach a deviation no greater than 0.8 mile per an hour of flight. A basic system can cost as much as ten thousand dollars, compared to the mere dozens of dollars (and maximal precision, of course) embodied in the cost of a GPS-based navigation system.

According to Shai Palti, Executive VP for Business Development at El Cielo, the most sophisticated navigation systems today are built with an inertial backup that is connected to the GPS at all times. So long as satellite signals are received, the computer carries out a comparison between the precise data input and the data received from the INS. When the satellite system goes beyond GPS reception, the inertial navigation systems know their exact start position, and the correction that they require from this point and onwards. This stems from the knowledge gained by the previous comparison between the INS data to the GPS system, up to the loss of the signal.

In order to avoid losing the time dimension precision when the navigation systems lose contact with the GPS satellites, some integrated systems utilize atomic clocks, which are sufficient for providing the precise time – just like the clocks in the satellites themselves.

Besides Israel, Switzerland and the US are the only other countries developing atomic clocks that are sufficiently complex for military purposes.

Atomic clocks calculate time with near absolute precision, as they follow the movement of atomic particles, just as “traditional” clocks follow the movement of a pendulum. The importance of absolute precision of time when discussing a navigation system installed on an armament, moving at tremendous speed, is exemplified by the fact that a three nanosecond deviation could equal a one meter deviation from the target.

The Israeli company Accubeat has been developing atomic clocks since 1994 (the company sold half of its shares to Rafael in August). In addition to atomic clocks produced for various systems worldwide, Accubeat develops navigation systems based on atomic clocks, which provides a complete substitute for GPS-based navigation.

“We are talking about very advanced technology,” Accubeat’s CEO, Beni Levi tells IsraelDefense.

“In principle, one can say that the atomic clocks mimic the method that GPS systems use to locate a position. Just as GPS satellites know their orientation in space vis-à-vis predetermined ground positions, atomic clocks enable the determination of other objects in space, relative to predetermined points on the ground. If there are atomic clocks at such sites, then their time is entirely precise, and they can be used for performing “incisions” which allow for pinpointing positions.


Another method for navigating weapon systems towards their targets without GPS dependency, and with absolute precision, is through the use of scene-matching technology. Rafael is considered the world leader within this field (read more about screen-matching technology on p. 22). The Israeli Ministry of Defense has partnered with the defense industries for the initial development of a future navigation technology called “Quantum Navigation.” This technology is expected to be operational only in another decade. At this stage, the Israeli MoD is not providing detailed information about its progress.

What about products based on GPS alternatives?

Israel Aerospace Industries (IAI) and Elbit Systems have both developed systems to assist forces in reaching their targets, even in a GPS-jammed environment.

The first system designed for vehicles was produced by IAI, and called the Advanced Navigation System (ADNAV). It weighs 2.2 kilograms, is based on a GPS package, and is backed up by internal sensors (including fiber optic-based gyros and accelerometers).

The system hooks up to a satellite, downloads the coordinates of its target, and then utilizes inertial sensors to provide autonomous navigation—even without satellite coverage. There are those who claim that the ADNAV has a deviation rate of no more than one percent of the distance traveled when in an inertial navigation mode.

The second system developed by Elbit Systems is called S-NAV and is intended for infantry soldiers moving on foot. The system is roughly the size of a pack of cigarettes and weighs approximately 155 grams.

According to Elbit, the S-NAV can detect the number of steps a soldier takes, the way he walks, and other movements, in order to estimate his position (with a deviation of 1-2 percent from the target’s coordinates).

One can discern how much the IDF is switching to non-GPS navigation by the fact that Elbit Systems intends to equip even Knight-class commander vehicles—primarily intended for logistical missions—with inertial navigation systems.

“We don’t want to be dependent on GPS, even in the field of logistics,” says a security source.


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