十万个为什么·科学启蒙30篇（2）
16 / 30
正在校验访问权限...
How Do GPS Devices Know Your Exact Location?
GPS设备如何知道你的精确位置？
-
GPS devices receive signals from at least four satellites orbiting Earth at 20,000 kilometers high.
-
Each signal carries precise time data from atomic clocks aboard the satellites.
-
The device calculates distance to each satellite by measuring how long the signal took to arrive.
-
Using trilateration, it pinpoints your location where three imaginary spheres intersect.
-
Tiny timing errors—even one-millionth of a second—can cause position mistakes of hundreds of meters.
-
Ground stations constantly monitor and correct satellite orbits and clock drifts.
-
Your phone combines GPS with Wi-Fi and cell tower data to speed up and refine location fixes.
-
Atmospheric delays slow down signals, so advanced receivers apply real-time correction models.
-
Military GPS uses encrypted signals for higher accuracy than civilian versions.
-
That’s how your map app knows whether you’re on the left or right side of the street.