A New Spin on Radar
SOLID-STATE RADAR BRINGS THE POWER OF TODAY’S TECHNOLOGY TO AN OLD SOLUTION.
The pilothouse was in night mode, screens dimmed. A low-hanging curtain of clouds magnified the darkness that seemed to swallow the boat and gave the deck underfoot the advantage of surprise with its erratic movements. Watchstanders kept a weather eye on the AIS, plotter, autopilot, and radar. Squalls and ships, tugs and tows, even waves breaking on a reef show up on that radar. And unlike the electronic chart or the AIS, radar doesn’t show an idealized version of the world beyond the pilothouse windows. Instead it pings back just the facts, such as they are (if you’re able to interpret them): traffic and weather, buoys, land, even birds. The value is unmistakable to experienced boaters who read these displays closely and have faith in what they see.
The trust boaters place in the information that instruments provide is a key part of letting electronics help extend our safe boating time well into the dark hours and foggy days. New technologies may be a welcome addition to the cause, but will they—or should they—replace the proven performance on which we’ve relied for years?
Since pulse-compression radar left the limitation of military service five or so years ago, marine-electronics companies have been looking at incorporating the system into recreational helms. Most marine radar signals from both solid-state and conventional pulse radar operate within the X-band. Navico (parent to Simrad, Lowrance, and B&G electronics brands), Furuno, and U.K.-based Kelvin Hughes all have solid-state radar systems, but so far Navico is the only one to bring a system for recreational boaters to market: Broadband radar, now in its fourth generation. Furuno ( www.furunousa.com) has an S-band radar available for commercial vessels and has an X-band system in development, also for the commercial side. The Sharpeye system from Kelvin Hughes is also for commercial application.
With regard to solid-state radar, a Raymarine representative says the company has nothing to talk about right now. Garmin has a system for aircraft radar, but so far also has given no indi- cation of development for marine customers.
The latest addition to the field is an openarray radar series from Simrad ( www.simradyachting.com), dubbed Halo, that is designed for recreational boats. It aims to use solid-state radar technology to improve on many of the features we’ve come to take for granted from conventional pulse radar. Whether these radars succeed or not remains to be seen—the stated goals are lofty. The series consists of three models including 6-, 4-, and 3-foot openarray antennas that are compatible with Simrad’s NSS and NSO evo2 multifunction displays, and sell for $5,500, $5,000 and $4,500 respectively. Halo-3 and Halo-4 are available now, while Halo-6 will begin shipping in August. Simrad says the brushless motors and helical gears that turn the antennas are maintenance free and operate quietly, (43 decibels at 48 rpm), and that the solid-state transmitter will not degrade over its 10,000-hour service life.
“It has no magnetron,” says Don Korte, senior radar product manager for Simrad. “It’s powered to 25 watts using Gallium nitride. It’s a new type of technology that is in cell-phone towers now and in military radars.” Instead of the 4- and 6-kilowatt magnetrons you know from conventional open-array pulse radar, the new system uses a spread-spectrum X-band transmitter to deliver a signal using what’s called “pulse compression.” Simrad describes the signal as similar to the CHIRP used in the company’s latest sonar products. Moreover, as Halo ranges out, the signal burst is comprised of as many as six different pulse lengths consisting of a range of frequencies, rather than just one, that upon echo return provide large amounts of data about the distance and direction of targets.
Simrad’s designers understood that short pulses provide good minimum range, but poor long range performance. At the same time—you guessed it—long pulses work well at long range but don’t do so well up close. In layman’s terms, Simrad decided to