Summer 2006 Issue

A Hot Spot GPS Finder

Kenwood teams up with AvMap to give weak-signal operators precise
driving instructions to that high, dirt-road site . . .

By Gordon West, WB6NOA


On your upcoming hilltop VHF/ UHF expedition, you won’t necessarily need to bring a laptop along to see detailed color maps, along with APRS position-hit-callsigns all around you. A completely portable GPS bi-directional navigating receiver can do it all, with one simple cable between the receiver and a Kenwood D-7 handheld or D-700 mobile rig.

“I slip my D-7 into my vest pocket and run the cable to my portable GPS chart display, and I can walk anywhere and everywhere squawking my GPS position on APRS while also receiving and displaying APRS stations and their callsigns right on the GPS color-map display,” comments Don Arnold, W6GPS, working with Kenwood Corporation and C-Map Group, which brings in the portable GPS charting receiver from its parent company in Italy.

“For weak-signal operators, a combined GPS that also reads grid squares and sub grids, with bi-directional capability for receiving APRS positions of other weak-signal operators, has allowed many microwave groups to speed up dish pointing,” adds Don, who is a recent convert to the exciting world of 10 GHz and above.

A few years ago, a handful of Garmin GPS receivers could also show APRS received callsigns, but the display was relatively small, plus it required additional keystrokes within submenus to display driving instructions to the distant callsign on the screen. With the new AvMap, a minimum number of keystrokes let you easily “ITT”—Intercept To Target.

It has been just one short year since AvMap introduced its first GPS color-map receiver specifically designed for the amateur radio market. A provided Y cable split out NMEA GPS 1200-baud position sentences and sent them to GPS TNC-enabled equipment such as Kenwood, plus ICOM and Alinco, radios with built-in (optional) TNCs. The first unit was called Geosat 2, and the hot GPS receiver actually was built right into the antenna unit. The split out of the data occurred before the GPS NMEA sentence reached the 12-volt 51/2-inch display head.

Then came Geosat 2.5, putting the driving-instruction speaker in the back of the display unit, and switching the power plug over to a simple cigarette-lighter-plug assembly. Both the 2 and the 2.5 included a CD of the entire country, with 256 MB preloaded in a proprietary compact flash card with approximately six states loaded with TeleAtlas street-level mapping, plus over 4 million Point of Interest details, including hotels, restaurants, gas stations, schools, and campgrounds.

Don Arnold, W6GPS, works AvMap on the test bench with a Kenwood D-7 handheld rig.

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