Sea Giraffe Stands Tall Among Surveillance Radars
Designed for small combatants in a challenging environment
The Saab Sea Giraffe radar is providing big radar capability in a small package. The surveillance radar is well suited for small combatants, such as corvettes and frigates, and has proven to be an effective and reliable performer in very harsh operating environments.
Sea Giraffe provides the volume search radar for USS Independence (LCS 2), one of two variants being evaluated for the Navy’s littoral combat ship. “It is integrated into the LCS open computing infrastructure as an element of the integrated combat system,” says Carlo Zaffanella, vice president for the Open Combat Solutions business of the Mission Integration Systems division at General Dynamics Advanced Information Systems.
“Early in the LCS program, we conducted an extensive best-of-industry trade study that evaluated volume search radars from around the world. We chose the Sea Giraffe because it provided the best proven performance for the target cost and met or exceeded all of the requirements of the LCS program,” Zaffanella says.
According to Zaffanella, Sea Giraffe integrates well with the Independence combat management system. “General Dynamics’ open computing infrastructure approach to LCS provides a flexible, scalable IT backbone utilizing nonproprietary interfaces capable of integrating best-of-industry technologies to ensure that a variety of weapons, sensors and effectors can be integrated into the ship’s combat management system. As a result, Sea Giraffe is able to seamlessly integrate its Identify Friend and Foe (IFF) capability to provide the combat management system with a correlated IFF-radar track. This open computing infrastructure methodology also allowed us to fully integrate data from the SeaRAM launcher with the Sea Giraffe radar to provide a single integrated situation awareness picture for the ship’s self-defense,” he says.
During Navy trials, the Independence crew demonstrated a proficiency in utilizing the capability of the Sea Giraffe to successfully conduct evolutions in all conditions, Zaffanella says.
The Navy’s Board of Inspection and Survey (INSURV) scored the USS Independence (LCS 2) combat system “detect to engage” sequences at 98 out of 100 possible points. “The Sea Giraffe performance was instrumental in achieving that demonstrated performance,” Zaffanella says.
Because of the experience with LCS, Zaffanella says General Dynamics would consider integrating Sea Giraffe into other programs. “Based on the Sea Giraffe performance to date, we would consider integrating Sea Giraffe for other systems depending upon the specific requirements of those systems and how we could best meet those requirements to the satisfaction of the customer,” he says.
Designed for a challenging environment
Saab developed Sea Giraffe and its fire control radars to operate in the littoral environment in the Baltic. “We have 35,000 islands around Stockholm alone,” says Bo Wallander, a retired Swedish Navy captain now working for Saab. “We need a system that can fit on a very fast, small and stealthy ship.”
Sweden’s 650-ton Visby-class corvette is such a ship, with both the Sea Giraffe AMB 3D surveillance radar and the Saab Ceros 200 Fire control radar system – which features the Saab 9LV combat management system. Its stealthy shape and all-composite construction make it very difficult to detect; its gas turbines and diesels can achieve speeds in excess of 35 knots; and its sensors and weapons make it a formidable warship is a very unforgiving maritime environment. “Its purpose is to kill,” Wallander says.
Sweden’s long and rugged coastline is adorned with 100,000 islands altogether, so Visby is designed for the littoral operating environment. “Nothing really happens on the open sea. It takes place in the littoral,” Wallander says.
The Sea Giraffe system is engineered with new technology for improved capability balanced with reliable and proven systems that are maintainable, rugged, and affordable. “The system must survive the environment,” Wallander continues.
The Sea Giraffe family of surveillance radars can be scaled to the requirement and the size of the ship. Saab engineers say there is always a tension between complexity and simplicity. Bigger is not always better. A smaller size means less topside weight and less interior equipment, less cooling required, smaller radar cross section, and better accessibility for equipment maintenance.
“We don’t want a heavy antenna on a ship,” says Wallander.
In addition to the Independence-class littoral combat ship for the U.S. Navy, the Royal Australian Navy recently selected the Sea Giraffe AMB for its Canberra-class amphibious ships. The Australian and New Zealand Anzac-class frigates operate the system, as do the Canadian Halifax-class frigates, Malaysian Lekiu-class frigates, Poland’s Orkan frigates, and the Baynunah-class missile corvettes for the United Arab Emirates.
AMB stands for agile multi-beam, and incorporates a stacked beam solution, according to Ted Ackerstierna, Director, Sales and Marketing, Americas for Saab. “Multiple receiver beams are stacked in altitude in order to instantly cover a large search volume in altitude. It also results in a 3D radar performance where you very accurately can measure target altitudes. The Giraffe has 12 simultaneous receiver beams in elevation and is using mono pulse technique to calculate the accurate elevation.”
Both these features results in more time for the commanding officer onboard to react and act upon an air or surface threat.”
Sea Giraffe can detect small, fast moving targets at altitudes up to 65,000 feet at elevations up to 70 º. It provides air and surface surveillance and tracking, target identification weapons control, and can track rounds fired to determine accuracy. “All this is done simultaneously,” Wallander says.
It can simultaneously handle multiple threats approaching from different directions and altitudes, including fast moving surface-skimming and anti-ship cruise missiles.
Sea Giraffe automatically can detect and track 200 air targets (including IFF tracks), 400 surface targets and 50 jammer emitters at one time, without manually selecting each track and assigning a track number.
It is also optimized to detect hard-to-see surface targets in a severely cluttered environment. “This radar can find really, really small targets, such as life rafts filled with explosives, or pop-up periscopes” Wallander says.
To contribute to stealth, Sea Giraffe can be configured with a stealth radome built with Frequency Selective Surfaces (FSS) to minimize radar cross section (RCS) and infrared signature. ESM, ELINT and/or COMINT gear can be mounted on top of the Sea Giraffe within the radome.
According to Ackerstierna, Sea Giraffe operates in the 5.4-5.9 GHz frequency range. “These frequencies belong to the C band, and is the best solution if you want a radar for both surface and air detection and tracking in both bad weather and in a heavy cluttered environment, such as in the littorals.”
“The radar can operate with a rotation rate of either 30 or 60 revolutions per minute (RPM). In order to have long range surveillance the transmitted pulses must have time to come back and be received before the next pulse get’s transmitted,” Ackerstierna says. “The RPM must be adjusted to the pulse repetition frequency and the maximum range the operator requires. High RPM means high data update which is important when countering high speed threats.”
Sea Giraffe features both a travelling wave tube (TWT) high power transmitter and a low probability of intercept (LPI) mode. “TWT transmits high power in the search volume in order to detect targets at long ranges. This permits an opponent to receive some of that power with ESSM, also at long range. To decrease the detection range for an opponent, the low power mode can be utilized,” Ackerstierna says.
Because Sweden is a small country, it needs to develop versatile and highly capable platforms and systems with export potential to reduce overall development and procurement costs, especially complex systems. “It takes a long time to develop radars,” says Wallander.
“The lowest level system in a system of systems is the most important system,” says Wallander. “Everything from sensor to shooter must be the same quality.”
Saab’s Giraffe family of radars also includes a “Land Giraffe” variant, which can be truck-mounted to provide surveillance and protection for forward operating based against incoming rockets, artillery or mortar rounds.
Capt. Edward Lundquist, U.S. Navy (Ret.), is a principal science writer for MCR Federal, LLC.