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...brought to you by none other than Oldsmobile.

Here's a excerpt from a late-90s review comparing Guidestar to Cadillac's OnStar and BMW's in-car nav.

Simple relative positioning systems that utilize only NAVSTAR data, like when using a GPS system with your laptop computer in the car, typically have no idea about specific street information, such as dead ends, one way streets, etc. In effect, such GPS-only systems are nothing more than an elaborate, highly accurate compass. As these relative position-only systems are totally GPS data-reliant, you also have to wait for a triangulation fix to inform you and the on-board lap top as to where you all are at system start-up. But who wants to sit in the car and wait for up to fifteen minutes to get a fix? More critically, the GPS signal can easily be blocked by tall downtown buildings. And, of course, the GPS signal is always absent when going through a tunnel or when you are in an underground garage. Finally, such GPS data-only systems do not give you audible turn by turn commands. You always have to take your eyes off the road to look at the computer display.

Turn by turn guidance deals with all these thorny GPS issues. It works without any satellite data. Instead, it utilizes "dead reckoning" data collected from vehicle motion sensors located in the car, and compares that vehicle data with on-board digital maps. This dead reckoning data includes speed, turning radius, and distance traveled When you have all three components; GPS, dead-reckoning, and digital maps; you've got the whole where-the-hell-are-we enchilada. An excellent example of one such complete GPS system is Oldsmobile's Guidestar system, available in their Bravada sport-ute, and Eighty-Eight and LSS sedans. It was the Bravada-installed Guidestar system that we reviewed.

The Oldsmobile Guidestar system is made by Rockwell, the same folks who designed and built the GPS/NAVSTAR satellite system on behalf of the DoD. Needless to say, this company has an inside track on GPS. As explained by Rockwell, which also markets the system under the Pathmaster name, the dead reckoning system instantly computes relative changes in the vehicle's position. The Guidestar maps show where you are by using GPS data and comparing them with dead reckoning data collected via speed pulses from the Bravada's tail lights, as well as from a directional sensor that senses turns. Via map matching,

Guidestar continually determines the shape of the Bravada's route by comparing its dead-reckoning "track" to actual road layout. It does this by using algorithms to compute changes in direction and distance traveled. As new data is received from the dead-reckoning function, output coordinates are linked to known points on a digital road map, and the algorithm "snaps" the Bravada onto the road network.
For example, says Rockwell, if our Bravada was tracking on a north-to-south road for 3.6 miles, and we made a 90 degree turn onto an east-to-west road, the map matching function of Guidestar would select the street with the highest potential at the new coordinates. It would compare this calculated position with a GPS location and determine a correction factor between the two. The system would then automatically update and adjust the Bravada's position on the map display. In addition to correcting for degradation or loss of satellite signals, this method also improves GPS accuracy from 100 to 10 meters.

Regardless of how a destination is selected, Guidestar calculates the quickest route, and can even provide alternatives in the event that we wanted to avoid freeways. Once we selected a destination, the Guidestar system begins its search outward from the known location to our requested destination, reviewing all possible routes simultaneously. It then begins to eliminate possibilities based on speed limits, road class (highway, surfaced, unsurfaced), and the number of maneuvers (for example, right turns are more desirable than left turns), until one route remains to where we wanted to go.

In the Bravada, you are informed about all these course changes by either looking at the display or via an audio prompt. The audio prompt is a whole lot safer way to travel than continually looking down at a driver distracting display. Using Guidestar is easy. The Guidestar system consists of a small stalk mounted display, with several simple to operate buttons that offer quick menu navigation. You get comprehensive detailed city coverage, plus points of interest and landmark info for airports, hotels, gas stations, ATMs, etc., Lastly, it has inter-town coverage including all roads to places having a population exceeding 500.

When the system starts up, it indicates that you are cruising only on dead reckoning. When the GPS data is finally locked in, a status bar in the Guidestar display changes color to let you know that both guidance systems are on line. The turn by turn feature really works well. We discovered that rotaries -- traffic circles -- presented a particularly good test for a GPS system. Guidestar always sailed through these circular challenges with no problem.

In the Bravada, the turn by turn map data were contained in PCMCIA drive cartridges located in a compartment at the vehicle's rear. The map data is supplied to Rockwell by Etak. Dead reckoning systems are only as good as the car's on-board map data base. So, if there is new road construction with detours, then the turn by turn map data in those cartridges is probably out of date. Accordingly, the data on the PCMCIA drives must be periodically updated by Oldsmobile.

We experienced this out of date data problem when going through Boston. The central expressway running through the heart of the city is being all torn up. Guidestar had no knowledge of these road changes and detours. However, the GPS system could still get a fix on us, and using the digital map display, would offer guidance on how best to get to our destination. As in all high tech systems, even when you wear both belt and suspenders, your pants can still fall down.

When purchased from Oldsmobile, the Guidestar system will set you back $2,495. It brought the Bravada sticker up to $30,285. Each additional cartridge containing information for a specific region of the country costs $400. To revise a cartridge, say you move from Boston to New York, costs $150.

If you never experienced Guidestar, just go rent a Hertz car and rent up the NeverLost unit. That's Guidestar still in use today!

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