A look at the new portable GPS systems says a lot about what is driving the market for these products, and what we can expect to see in the coming year.

Manufacturers are clearly targeting the GIS arena -- its user base is far larger than that of precision, high-end surveys -- and the growing competition has dropped sticker prices. Since data collection is optimally done using GPS, the lower-priced systems may find greater use in agencies and departments across the board -- redevelopment and transportation, utilities, urban and regional planning -- all have needs in asset management and GIS-based data display.

With the exception of a GPS-based vehicle tracking system and a sophisticated highway survey vehicle, the GPS systems selected here are portable and designed primarily for mapping and asset management.

ASHTECH

The Ashtech Reliance GPS is a compact field asset-management system specifically designed to work with GIS. It includes a Windows-based processor capable of direct data transfer to GIS, CAD and other Windows programs.

The office software suite has a wide range of capabilities, with mission planning, time and location for each recording session, location of each feature relative to other assets, operator and instrument identification, GPS accuracy of each point feature, and a built-in editor for field asset labeling and descriptions. Capabilities also cover datum and RINEX conversion, and coordinate system transformation.

Accuracy for the standard Submeter System is reported to be 75 centimeters in either static (one-second point occupation) or dynamic (walking) mode. The Decimeter System processes both code and carrier data, and is reported to have 10-centimeter, on-the-fly accuracy. Optional software is available for one-centimeter accuracy.

The Reliance comes in two models; both use the Ashtech SCA-12 GPS receiver and a handheld datalogger/controller. Both models accept realtime or post-processed differential corrections. A 4.5MB memory stores 35 hours of data when recording at five-second intervals, or seven hours of data recording at one-second intervals. The controller has an alpha-numeric keypad and a backlit, eight-line x 42-character LCD (liquid crystal display). According to Ashtech, the controller is waterproof against accidental immersion, and can withstand a six-foot drop onto a hard surface. The system is light, relatively easy to use, and provides a rapid means of developing and maintaining a wide range of asset databases, from power poles and water meters to wetlands and endangered species habitats.

STANDARD EQUIPMENT

12-channel all-in-view GPS receiver.

Reliance processor software.

Compact GPS antenna.

Backpack carrying system.

Two rechargeable receiver batteries (8 to 12 hours of operation).

Battery charger (110 or 220 VAC output).

Husky FS/2, or Psion Workabout handheld controller, w/FAMlog software.

Data cable.

Manuals.

LIST PRICE

Reliance Submeter: $6,950

Reliance Decimeter: $8,950

Husky FS/2 FAMlog: $3,995

Psion Workabout FAMlog: $2,495

For further information, contact Ashtech, 1170 Kifer Road, Sunnyvale, CA 94086. Call 800/922-2401.

CIMARRON TECHNOLOGIES

Cimarron's Skymark Vehicle Tracker is an automatic vehicle location (AVL) system that uses existing voice radio dispatch systems to track the speed, direction and location of mobile units.

The mobile unit's GPS coordinates are transmitted in packets (short bursts) to the base station, where they appear in realtime as a moving icon on a full-color map display. Included in every burst are the vehicle identification, speed, direction, position in latitude/longitude and a brief message. Software functions include display of the closest vehicle to a specific point or place; the distance and bearing between any two points on the map; and automatic time stamp and recording. The latter allows vehicle route logs to be played back for review. Dispatchers can also program mobile units to send position reports each time the unit's microphone switch is depressed; whenever the unit is polled by the base station, or at selected distance and time intervals. Units can be programmed to send position reports as