Even at current prices, a navigation computer is impressive. It can guide you from point to point in most major cities with precise turn-by-turn directionsspoken by a clear human-sounding voice, and written on a screen in front of the driver.
The computer works with an antennathat takes signals from no fewer than three of the 24 global positioning system satellites. By measuring the time required for a signal to travel between the satellites and the antenna, the cars location can be pinned down within 100 meters.
The satellite signals, along with inputs on speed from a wheel-speed sensor and direction from a meter, determine the cars position even as it moves. This information is combined with a map database. Streets, landmarks and points of interest are included.
Most systems are basically identical. The differences come in hardwarethe way the computer accepts the drivers request for directions and the way it presents the driving instructions. On most systems, a driver enters a desired address, motorway junction or point of interest via a touch screen or disc. But the Lexus screen goes a step further: you can point to any spot on the map screen and get directions to it.
BMWs system offers a set of cross hairsthat can be moved across the map to pick a point youd like to get to. Audis screen can be switched to TV reception.
阅读能力的提高包括很多因素,文章可以分为段落,段落可以分为句子,句子可以分为单词。
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