Small Smart Stuff Page 2

Electronics December 2002
By Ben Ellison

Small Smart Stuff
Part 2: Airmar also claims that the design delivers high performance.
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Besides the ability to set up and page through as many as five highly customized screens as I described earlier, Furuno's box has some other significant smarts under its little hood. For one thing, the RD-30 can do some math, such as watching the Speed Over Ground output from a GPS and keeping its own trip and vessel logs. It also contains a whole database of Loran to lat/lon conversion corrections and is quite adept at mixing NMEA data. The Achilles heel of the 0183 protocol is its intolerance of multiple data "talkers," or inputs. The RD-30 can listen to two inputs at once, display any desired info, and simultaneously send out a custom mix to either or both of its outputs. The user--or perhaps the user's electronics tech--can exercise on/off control of those outputs right down to the individual data string. This can be very handy in sophisticated systems, or for feeding a PC navigation program. The auxiliary output port also has a 12-volt feed, making it easy to daisy chain another RD-30 for more display options and/or more data mixing.

All the RD-30's features happen to match up quite nicely with a line of similarly innocuous but witty devices recently developed by Airmar. I'm referring to Smart Sensors, which look like standard through-hull, in-hull, and transom-mount depth transducers with water temperature and speed (through the water) options. Indeed they are transducers, but also much more. Each housing also contains the brains to turn raw sensor readings into NMEA 0183 data. Its cable leads not to a control head and display, but to any device capable of showing 0183 numbers.

The simplicity of a Smart Sensor is impressive on its own, but Airmar also claims that the design delivers high performance. Putting the electronic guts right into the transducer eliminates signal degradation from cable runs, which can subsequently extend up to 330 feet, plus Airmar equipped those guts with fast, sensitive digital signal processing. The purported results are accurate speed readings up to the 40-knot range, temperature readings to hundredths of a degree, and depth readings even in very shallow water, or under the duress of backing prop wash; I've heard confirmation of these claims from testers. The transducers run at 170-kHz or 235-kHz frequencies so that they can be used with to regular 200-kHz fishfinders without interference.

The RD-30 can do presentation magic with the Smart Sensor's precision data streams, a happy relationship that Furuno's marketing department is celebrating, but bear in mind that each is an independent player capable of other 0183 friendships. And I've seen more innovative display, data mixing, and sensor devices being developed with 0183. It seems a little ironic that just as the world of marine electronics focuses on fast networks, multitasking, and color everything, there's a spurt of originality largely employing older technologies. I'm heading off to the winter boat shows soon, where I'm sure to be dazzled by all sorts of gizmos. I'm also going to keep an eye out for R2D2-type gadgets that make much smarter and more useful sidekicks than they may first appear.

Furuno USA Phone: (360) 834-9300. Fax: (360) 834-9400.

Next page > Electronics Q&A > Page 1, 2, 3

This article originally appeared in the January 2003 issue of Power & Motoryacht magazine.

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