大学英语教程4原文翻译如下：
Two of the most frustrating things about driving a car are getting lost and getting stuck in traffic。While the computer revolution is unlikely to cure these problems, it will have a positive impact。
Sensors in your car tuned to radio signals from orbiting satellites can locate your car precisely at any moment and warn of traffic jams。We already have twenty-four Navstar satellites orbiting the earth, making up what is called the Global Positioning System。
They make it possible to determine your location on the earth to within about a hundred feet。At any given time, there are several GPS satellites orbiting overhead at a distance of about 11,000 miles。
Each satellite contains four "atomic clocks," which vibrate at a precise frequency, according to the laws of the quantum theory。
开车最头疼的两大麻烦是迷路和交通堵塞。虽然计算机革命不可能彻底解决这两个问题，但却会带来积极的影响。
你汽车上与绕轨道运行的卫星发出的无线电信号调谐的传感器能随时精确地确定你汽车的方位，并告知交通阻塞情况。我们已经有24颗环绕地球运行的导航卫星，组成了人们所说的全球卫星定位系统。通过这些卫星我们有可能以小于100英尺的误差确定你在地球上的方位。
在任何一个特定时间，总有若干颗全球定位系统的卫星在11000英里的高空绕地球运行。每颗卫星都装有4个“原子钟”，它们根据量子理论法则，以精确的频率振动。
As a satellite passes overhead, it sends out a radio signal that can be detected by a receiver in a car's computer。The car's computer can then calculate how far the satellite is by measuring how long it took for the signal to arrive。
Since the speed of light is well known, any delay in receiving the satellite's signal can be converted into a distance。
卫星从高空经过时发出能被汽车上计算机里的接收器辨认的无线电信号。汽车上的计算机就会根据信号传来所花的时间计算出卫星有多远。由于光速为人熟知，接收卫星信号时的任何时间迟缓都能折算出距离的远近。