Radar functions increase as developers shift to software and digital modules
A changeover to more digital components is enabling new, sophisticated techniques
- By Terry Costlow
- Oct 01, 2012
Radar systems are evolving rapidly, using improved technology to bring new benefits. A changeover to more digital components is enabling techniques such as beam forming, which improves surveillance capabilities by letting operators focus on targets more quickly.
Leveraging the continuing advances of semiconductors also helps cut costs and reduce field failures, which will help budget-conscious military buyers justify acquisitions. In maritime applications, the ability to monitor large areas is a key advance.
“With phased-array radar, you can have multiple phases that are transmitting at the same time. You can use advanced waveforms to help cover 360 degrees,” said Adam Razavian, deputy major program manager for above water sensors at the Naval Sea Systems Command. “Beam forming is critical; it helps you cover a large area.”
Phased-array radar makes more efficient use of the radar timeline, performing multiple tasks or repeated tasks within each scan. Digital technologies help operators quickly focus in on objects of interest, even in difficult environments.
“Active electronically scanned arrays (AESA) search volumes faster and more efficiently, and offer improved revisit rates, which supports tracking, for example, of highly maneuvering targets within challenging clutter and jammer environments,” said Erik Smith, general manager of Saab Sensis Defense and Security Systems. “In the past it might have taken three scans to establish a firm track on a target, whereas the latest advances in AESA technology enables the radar to revisit the target multiple times within a single scan and thereby establish track.”
Much of the progress in radar technology and performance stems from the continuing increases in microprocessors and other digital devices. Many benefits come from new technologies like digital beam forming, but they don’t come for free. Most developers feel that increasingly fast processors will let them bring even more benefits in the future.
“When you generate the beam in software, you can look everywhere at once. You can also pick your resolution,” said Pierre Poitevin, general manager of FLIR Radars. “The main drawback to digital beam forming is that it requires a significant amount of signal processing. Every year, that’s less of an issue because the CPUs (central processing units) get more powerful, up to a 12-core device where each core runs at 1 GHz.”
More benefits will come as microprocessor speeds rise. Radars will be able to perform different functions, shifting quickly to adapt to changes on the battlefield.
With faster signal processing, we can go to dual-mode scanning,” Poitevin said. “Algorithms can be configured for a fast-scan mode or a Doppler-scan mode, so you make changes like going to a faster scan rate when the ground is flat with few obstructions. You can switch modes in less than a minute.”
Most of the advances come in silicon. But in the high-frequency world of radars, gallium arsenide has been used because it’s faster than silicon. It’s now being replaced by an alternative—gallium nitride—that trims power consumption, which is a huge factor given the amount of heat generated by speedy, power-hungry chips.
“Moving to transmitters and receivers that use gallium nitride has been a big contributor to improved efficiency and lower power,” Razavian said.
He also noted that other digital devices have displaced larger analog designs. Shifting from analog circuitry, which is often called a black art, brings many benefits.
“Elemental-level digitization has helped reduce noise,” Razavian said. “The less noise there is, less effort is needed to clean up the signals.”
This helps improve costs, since recurring hardware costs decline as chips integrate more functions. The cost of software is minimal once programs have been written and fully tested.
“When we move more of the design chain into the digital world, it’s cheaper and we have more flexibility. It also improves reliability. Software is basically reliable once it’s been tested,” Poitevin said.
It’s the Economy
This focus on cost reduction is driving many changes, ranging from initial design concepts through techniques that lower operating costs. On the design side, engineers have devised techniques that make it simpler to expand systems to suit needs and budgets.
Part of this focus is on creating modules and subsystems that can be linked together to enhance coverage. This design goes well beyond electronics. The high speeds of signal processors in new systems often generate large amounts of heat, so cooling the systems is a key factor.
“Today’s radars are very scalable, which has a huge benefit for costs,” Razavian said. “You can add a module, each one in a sensor is an operating radar on its own. To add these modules without changing the cooling system, it must be designed from scratch to be scalable. The radar needs to operate at a given temperature, even when it’s grown to twice its size. If you can cool the radar efficiently, it can radiate far more power.”
Integrating multiple functions into a single system is another cost cutting avenue. When multiple radar systems are consolidated into a single system, both initial costs and field maintenance expenses can be reduced.
“The U.S. Marine Corps Ground/Air Task Oriented Radar (G/ATOR) system, for example is one where the missions of five legacy systems will now be performed by the single G/ATOR system,” Smith said.
Radar designs are also moving away from the unique components that have been common in many designs. Both the military and the overall electronics industry are moving toward hardware that shares common traits so components and modules can be designed by multiple providers.
“Open systems and open architectures with well-defined interfaces play a big role in [reducing] overall costs, they let us compete on modules instead of full systems,” Razavian said. “COTS is also a big factor in our cost-reduction efforts. When modules are repeatable, with fewer unique parts, it’s also much easier to troubleshoot and repair them.”
He also noted that the powerful processors that help design engineers provide enhanced benefits are helping personnel in the field. Newer systems regularly perform diagnostics, so systems can alert operators as soon as problems arise, even directing technicians to the faulty component.
“A major factor in lifetime costs is that systems are becoming smarter,” Razavian said. “The system tells you when there’s a problem, and it isolates it so the technician can go directly to the problem, rather than troubleshooting the entire system.”