Product Focus: GPS

A look at some of today's GPS products and systems.

by / September 30, 1996
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.

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.

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.
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'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 often as every second.

With SA (Selective Availability, the government's imposed accuracy degradation for non-military GPS use), 95 percent of mobile-unit positions are true within 100 meters. With realtime differential correction -- provided by USCG or ACE beacons, or by private companies for a nominal subscription -- accuracies are on the order of 5 to 10 meters.

The system uses any type of paper map that can be scanned and referenced to latitude/longitude coordinates. Map size and scale are limited only by hard disk space.

According to Cimarron, the software, which runs under Windows 95, includes advanced bitmap graphics that enable users to manipulate map files quickly. Vehicle Tracker is compatible with trunking, UHF, VHF, microwave, and telephone transmission systems.

Modem (installed inside radio transceiver).
GPS receiver/controller.
Controller (bi-directional modem).
Single or multichannel RS232 cable (Cimarron can provide the PC).
Vehicle Tracker software.
Base hardware, software and single map scanning: $9,145
Mobile hardware: $1,350 per vehicle
Base-station computer: Pentium PC with 16MB RAM and 500MB of hard disk (ASCII output from the controller is routed to the computer's serial com port via RS232).
For further information, contact Cimarron Technologies Corp., 934 South Andreasen Drive, Suite G, Escondido, CA 92029-1919.

The 8600RT is a lightweight GPS/GIS data collection system made up of the MX 8600 GPS receiver, MX 41R Beacon receiver, GPS/Beacon antenna, battery charger and backpack. The MX 8600PC software package is optional. The system is designed for GPS/GIS data collection, and has output formats compatible with commercial mapping and GIS software, including ArcInfo, ArcView and AutoCad.

The six-channel, waterproof MX8600 uses carrier smoothing to improve reception in difficult areas. A special offset function is used to record position coordinates where signal reception is nonexistent. Users can record point and line features simultaneously -- a light pole, for example, while measuring a line. Data can be collected in realtime differential or post-processed differential mode.

According to the company, post-processed differential correction produces 1- to 3-meter accuracies (realtime accuracy is in the 1- to 5-meter range). The 8600 can be ordered with 1, 2, or 4MB RAM.

The Beacon receiver automatically seeks out and tunes to the frequency of the strongest DGPS signal. Software functions provide GIS data collection solutions from planning to output, including datum and grid selection, creating and editing databases in the field, creating and editing map displays, post processing, and combining multiple data-collection files before export.

The MX8600PC software package does not come with the MX8600RT system, but is available separately. This software package is needed in order to export data to the above mentioned GIS software.

MX 8600 GPS/GIS receiver.
MX 41R DGPS Beacon receiver.
Combined GPS/Beacon antenna.
Batteries and cabling.
Ergonomically designed backpack.
Basic system (MX8601R): $7,950
MX86900PC software: $1,430
For further information, contact Leica Inc., Navigation and Positioning Division, 23868 Hawthorne Boulevard, Torrance, CA 90505-5908. Call 310/791-5300, or fax 310/791-6108.

MSTAR is the new Windows-based professional software package for the ProMark X and ProMark X-CP (carrier phase) GPS receiver/dataloggers. The software is reported to be significantly faster and more comprehensive than earlier versions. The system was designed for survey, mapping, positioning and GIS applications.

Capabilities of the new software include mission planning, data collection, differential post-processing and data analysis. Satellite selection prior to field work assures data collection using the most favorable satellite geometry.

MSTAR speed is essentially a function of its ability to convert multiple files simultaneously; users can process numerous datasets using multiple control positions and defined data sessions. Both raw data and differentially processed results can be converted to commonly used GIS programs, including ArcInfo, ArcView and AutoCad DXF. Software capabilities include user choice of grid projections; conversion between virtually all datum and coordinate systems; and outputs in RINEX, ASCII and several other formats. Other features include statistical analysis, user-definable coordinate systems and GPS receiver communications. The software does not do network adjustments, but will output data that can be read by StarNet, the network adjustment program. The ProMark X-CP can also be used as a base station. Sub-meter operations, however, require both receivers to be CP versions.

In addition to the software and detachable quadrifilar helix antenna, the ProMark X and X-CP come with an external multipath-resistant antenna. Minimum software requirements are a 486 or higher, with minimum of 8MB RAM.

ProMark X-CP: $4,495
Upgrade to MSTAR for owners of ProMark X and ProMark X-CP receivers with earlier software: $495
For further information, contact Magellan Systems Inc., 960 Overland Court, San Dimas, CA 91773, 909/394-5000.

Except for something James Bond might drive, the smartest vehicle on six wheels has to be Roadware's ARAN (Automated Road ANalyzer). This state-of-the-art automated data-collection vehicle carries an array of integrated sensors that detect, photograph, and record the locations of potholes, ruts, cracks and pavement breaks; road-stress features such as texture, retroreflectivity, transverse profile, shim quantities, surface friction, passing zones, pavement width and roadbed thickness.

At the same time, ARAN videotapes rights-of-way in three dimensions and records the condition of pavement markers and road signs -- all with millimeter accuracy while traveling at highway speeds!

What enables the vehicle to record so much detail with precision is a system of highly integrated sensors -- differential GPS (DGPS); laser photodetectors, accelerometers; ground-penetrating radar, optical sensors, strobe lighting, aircraft gyroscopes, high-resolution video cameras, and post-production software that largely automate pavement-condition rating.

The software allows operators to review video logs and determine the exact geographic location of recorded objects by pointing and clicking on the image. Each frame of video has a unique eight-digit code that is cross-referenced with the linear distance along the highway. Unlike making on-site inspections and using mile markers for position references, Department of Transportation (DOT) personnel can develop GIS databases and maps from data provided by ARAN. The system can also be used to create and maintain inventories of assets such as bridges, guardrails, utility poles, fire hydrants, manhole covers and trees.

To date, 16 state DOTs have either purchased an ARAN or are contracting with Roadware Corp. for ARAN services. The system is also used in many countries around the world.

ARAN vehicles: $180,000 to $600,000 for most popular models, $1,000,000 for highly specialized vehicles
For further information, contact Roadware Corp., 147 East River Road, Paris, Ontario, Canada N3L3T6. Call 519/442-2264, or fax 519/442-3680.

Trimble's GeoExplorer II GPS is a mapping and GIS data-collection tool as well as a navigation instrument. Powered by off-the-shelf AA alkaline batteries, the pocket-sized receiver provides 2- to 5-meter accuracy with realtime or post-processed differential correction. It tracks up to eight satellites, and stores 9,000 3D positions in a 256K internal memory. Raw and real-time corrected data can be stored in the same file to ensure continuation of data collection in the event differential signals are blocked. Raw data can then be corrected in post processing. Outputs accommodate ASCII, RTCM, SC-104 and XMODEM serial protocols.

The accompanying Pathfinder Office software is Windows-based, featuring hands-off data processing from downloading to exporting to a GIS or CAD system. A graphical user interface module has functions for editing, displaying and plotting features at any scale. The system will display background maps behind GPS data, which allows users to see where data has been collected and the relationship to previously recorded map features, such as roads or property boundaries. System capabilities include mission planning, data-dictionary development; editing, plotting and differential correction; and user-selectable map coordinates and output functions. Pathfinder can also be configured to automatically transfer data from the collector directly to the user's PC. The package supports all major GIS systems, including ArcInfo, ArcView, AutoCAD, Intergraph, MGE, ERDAS and GRASS.

GeoExplorer II, Part Number 28778-00.
Receiver with internal antenna.
PFINDER software.
Data download cable.
Set of alkaline batteries.
Carrying case with belt loop.
GeoExplorer II: $3,495
For further information, contact Trimble Navigation, Survey & Mapping Division, P.O. Box 3642, Sunnyvale, CA 94088-3642. Call 800/545-7762, or fax 408/481-8488.

Bill McGarigle is a freelance science and technology writer. E-mail: .