Knowing Where You Are
Written by Steve Goodman
SOTECH 2010 Volume: 8 Issue: 4 (June)
Point A to Point B and Everything in Between -
GPS and NAV
The great Yogi Berra once said, “If you don’t know where you are going, you’ll wind up someplace else.” Nowhere is that truer then on the battlefield. In fact, in combat operations, it is not only imperative to know where you are going, but also exactly where you, your fellow soldiers, your other assets and your enemies are—at any given moment. And that means reliance on GPS technologies and NAV systems.
Many of the modern day conveniences we take for granted actually had their start in the military—usually from the labs and research facilities of the Defense Advanced Research Projects Agency (DARPA). The internet was one of these, and GPS navigation systems are another. However, the units and technologies used by DoD are very different than what one might find on the dashboard of his or her car, or even within a commercial vehicle or aircraft.
“One of the main differences between military and commercial GPS receivers is in the capability of military receivers to decode additional signals that allow them to provide a more accurate position solution,” said Ben Ritter, business development manager, reference systems, GE Aviation.
Basically, GPS is a satellite-based navigation system that uses a specialized receiver to process radio signals, and uses that data to calculate location and velocity. The advantages of a GPS system are its worldwide coverage, no long-term drift, low cost for the user, and small size, weight and minimal power requirements. “The disadvantages,” said Ritter, “include short-term variability and signal denial due to blockage or jamming either intentional or unintentional.”
At a 2010 conference that was held at Tuft University’s Institute for Foreign Policy Analysis, General Norton Schwartz, Air Force Chief of Staff, said, “Jamming of GPS signals could present a very serious problem for U.S. military hardware.”
The lack of security is only one problem that is making GPS-only systems less than the ideal technology for military navigation. In fact, the increased demand on GPS satellites due to the widespread use of GPS beyond military applications has forced DoD to seek alternative technologies. According to a 2009 Government Accountability Office (GAO) report entitled Global Positioning System: Significant Challenges in Sustaining and Upgrading Widely Used Capabilities, the latest federally funded GPS program, Block IIF, is already more than $850 million over budget and is facing “significant technical problems that continue to threaten its delivery schedule.”
There are currently about 30 or so GPS satellites in orbit, the oldest of which were launched in the 1990s. According to the GAO report, these older satellites are in danger of failure. The first attempt to launch a new satellite under the Block IIF initiative was scheduled in February of this year, three months later than the November 2009 estimate of the GAO report. That launch was scrubbed due to technical difficulties, and twice since, with the latest failed takeoff occurring on May 24, 2010, just days before the filing of this report.
Launch delays of next generation satellites notwithstanding, the developers and users of NAV technology for DoD applications face other challenges as well. According to GE’s Ritter, “Military products, in general, can be much different than commercial or industrial products due to different environments and specific user requirements. Systems need to be able to withstand wide temperature ranges, high levels of vibration, humidity, dust, mechanical and thermal shock, electromagnetic interference exposure, and in some cases, nuclear exposure. In the case of GPS, the equipment must also be able to utilize the military signal that provides additional precision, security and tracking capability. The challenges of designing, qualifying and fielding those military systems generally lead to significantly different products from the commercial or even industrial variety.”
“When designing for DoD,” agreed Christopher Watson, director of marketing for Middletown, R.I.-based KVH Industries, “you have to meet a gamut of mil-spec requirements—salt, fog, dust egress—all of the environmental rigors. We do extensive in-house testing where we ‘shake and bake’ our products. We can dump liquid nitro into the systems; we raise the temperatures to 185 degrees. We stress our products to the breaking point for all of our military systems.”
In 2003, USSOCOM placed its first $1.4 million order with KVH Industries for its TACNAV military vehicle navigation system, as part of a large-quantity, multi-year SOCOM program.
INERTIAL GUIDANCE SYSTEMS
The way DoD is overcoming the limitations of global positioning technology is to use GPS in conjunction with other systems that will function as an adjunct to, or in lieu of GPS. One of the most popular such solutions is “inertial navigation.”
“Inertial navigation systems use sensors to detect physical motion such as rotation and acceleration of the host vehicle,” explained Ritter. “The sensor outputs are then integrated to derive the location, speed, heading and altitude of the vehicle. This self-contained solution is not reliant on other signal sources such as magnetic compasses, is very accurate over short time periods, and can provide high data rates. When the functionality of GPS systems are combined with the capabilities of inertial navigation systems [INS], the result is a blended solution that contains the best of both worlds.”
GE Aviation provides vehicle based navigation systems for land, air and seaborne assets.
KVH employs a similar technology that it refers to as a digital compass, designed to work with and back up GPS systems. “We invented and first fielded the digital compass with the Marine Corps, during the first Gulf War in the late ’80s,” said Watson. “A digital compass can actually register the distortions caused by an armored vehicle and cancel those out using software. So you have a very precise compass inside of a vehicle that is not being affected, distorted or made less accurate by the movement of the vehicle itself, or the gun turret above. It is fully self-contained, but then we can tie it into a GPS for example, so that way if there is a GPS outage, or blockage because you are in a city or because of weather, or because of some countermeasure action taken by the opposition, you are not left without navigation information.”
A BIRD IN THE HAND
Navigation technology, especially in the special operations community is not restricted to vehicular-based systems. SOCOM deploys a number of handheld tactical GPS and NAV devices.
Rockwell Collins, long a provider of navigational equipment and devices to the DoD has recently introduced its Defense Advanced GPS Receiver (DAGR) ruggedized navigation system. DAGR is a small and ultra lightweight handheld GPS with a user-friendly graphical user interface and moving maps. DAGR incorporates fieldtested and proven anti-jam technology, and is the first handheld GPS deployed by U.S. forces that uses Rockwell Collins’ proprietary security device, the Selective Availability Anti-Spoofing Module (SAASM).
According to the company, SAASM gives DAGR capacities that cannot be found in commercial GPS receivers, such as, “the ability to utilize the Precise Positioning Service signal via COMSEC crypto-key. SAASM gives authorized users the confidence to operate reliably in an electronically challenged combat environment that could render commercial GPS receivers inaccurate or nonfunctioning.”
DAGR is particularly well suited to the challenges of special forces operations. “The special operations forces, by nature of the missions they undertake, typically subject equipment to more stressful conditions than the conventional military,” said Gina Krug, principal marketing manager, soldier systems, Rockwell Collins. “One example would be the conduct of a high altitude, high opening [HAHO] military freefall parachute insertion. In a HAHO operation, special operators exit an aircraft in flight at altitudes of as much as 25,000 feet above ground level, deploy a ram-air canopy parachute and glide to a target. In an operation like this they might use a handheld GPS device for guidance to the drop zone. Exit altitude can be extremely cold. At that temperature the liquid in the LCD screen on most GPS receivers will freeze solid. The DAGR, however, is designed to operate in temperatures down to minus 40 Fahrenheit.”
As essential as some of these advanced handheld systems can be, any special operator will tell you that knowing exactly where you are and how to get from point A to point B sometimes can be done— indeed has to be done—with some very low-tech solutions. Pace counting has been employed by trackers, hunters and warriors in the field for generations. Also known as tally stepping, it is a technique that was used by Roman Legions, as well as Army Rangers in the Jungles of Vietnam. Pace beads are commercially available, or special operatives have been known to make their own.
Pace beads never crash or lock-up, cannot be jammed and can provide distance traveled data despite the terrain or weather conditions—even in total darkness. Pace beads certainly are a bit of an anachronistic method of navigation, especially given some of the devices previously talked about. However, they remain popular with Army Rangers, Delta Force, Green Berets, Navy Seals and the British Special Air Service, and thus bear mentioning.
WHERE WE ARE GOING
GPS and navigation devices have been and will continue to be enabling technologies for the warfighter. Irregular conflicts such as Operations Enduring Freedom and Iraqi Freedom have proven their indispensability. “The global war on terror and irregular conflicts we now face places added reliance on these systems as an integral component of overall battlefield awareness. Having the capability of situational awareness of friendly forces on the battlefield is widely held as a force multiplier. Integrated GPS/INS is clearly the best solution for providing that situational awareness,” concluded GE’s Ritter. ♦