ELECTRONICS
As we approached another daymark during our Miami
test, a second, smaller return showed next to the piling.
It was a buoy like those typically used with crab pots.
A similar nearby return was reflected from a swimming
seabird. Granted, calm water made returns from these
soft targets possible. But consider the Great State of
Maine, where water often is calm when conditions are
at their foggiest, and lobster pots in some places lie like
paving stones across the bottom. (If you think that’s
an exaggeration, go see for yourself.) Broadband Radar
would allow you to see a channel through that mess
of buoys, not to mention fog-obscured rocks, docks,
and bridges.
“IT’S MAGIC”
Greg Konig is vice president for Navico’s product line, a
role that can be likened to that of midwife to the birth of
new machines. During a press luncheon, Konig was asked
if he could explain how Broadband Radar works “in
layman’s terms.” Konig obviously did not want to launch
into a lengthy discourse over salad and sandwiches. “In
layman’s terms,” he said, pausing for effect, “...it’s magic!”
With help from Konig and other folks at Navico, I’ll now
attempt to explain how Broadband Radar works and how
it differs from conventional radar.
Conventional or pulse radar came into its own during
World War II, when England needed as much warning
as possible to challenge attacking German aircraft. Radar
developers wanted to be able to determine an enemy’s
range and bearing, and the farther away, the better.
These radars, like marine radars of today, sent out a
radio signal and then determined range and bearing from
the echo returned to the antenna after that signal had
encountered an aircraft. The signal was generated by a
magnetron, which has been compared to a valve opening
and closing to release pulses of energy.
In layman’s terms: Imagine you are standing blindfolded
near a house. You holler “hello!” and then listen to hear
the echo. Let’s assume you are changing direction like a
rotating radome as you continue to call “hello!” and listen
again. You holler, pause, listen; holler, pause, listen. Your
sense of hearing is more finely tuned than most, and the
echoes tell you that there is an irregular object nearby in a
particular direction at a specific distance.
Broadband Radar is a sexy marketing name for what
engineers call frequency-modulated continuous-wave
(FMCW) radar. The word “broadband” nowadays is
associated with good computer connectivity; Navico
justified use of the term because its radar emits signals
along a broad range of frequencies. It does this without a
magnetron, instead using two solid-state amplifiers: one to
Peter Swanson
This dual amplifier assembly is what spins around inside the
broadband radome. The upper portion transmits continuously,
while the lower portion simultaneously receives echoes.
transmit waves at continuously increasing frequencies, the
other to simultaneously receive their echoes.
Now, Mr. Layman, you are standing near the same
house, not hollering. You are whispering, “do, re, mi, fa, so,
la, ti, do; do, re, mi, fa, so, la, ti, do,” etc. As you rotate and
whisper, you listen for echoes, with an ear for nuance. You
don’t pause; you whisper and listen simultaneously. You
clock the echo from each discreet note and use these
streaming time-stamps to build a mental picture of a
building with a tree in front of it, but not touching.
“What’s really useful is not just that you can discriminate
two targets a mile away, but that you are able to quickly
discriminate what’s on their radar and relate it to what’s
around you,” Konig told me. “You are able to match what
you see on the screen to reality quicker than you ordinarily
could. It also eliminates sea clutter and rain clutter about
five times better than your traditional radar, and you don’t
have to tune the radar as much to get the signals to pop
out from the noise, so it is a much less painful experience.”
THIRD-PARTY EXPERT EVALUATION
Another broadband advantage over traditional radar is
that it requires no warm-up because it has no magnetron.
Switch it on, and within seconds you have a picture of the
waters around you. Traditional radar delays transmission
for up to 90 seconds. Add to this the fact that FMCW
radar has inherently better rejection of sea clutter and self-tunes depending on range scale. Together, these features
give the skipper the confidence to refrain from transmitting
during benign conditions to preserve battery state.
Enhanced situational awareness is only a button push
away—no tuning.
