Chapter 05 of 5
Lost in the City
Urban canyons, jamming and how your phone fills the gaps.
- Reality
A Fragile Signal
GPS signals are weak and can be blocked by buildings, trees and roofs.
- Urban Canyons
Bouncing Off Glass
In cities, signals bounce off buildings and arrive late, which can make your blue dot jump around.
- The Sky Layer
The Ionosphere
A layer of charged particles high in the atmosphere slows radio signals slightly, causing errors if uncorrected.
17 more cards in this chapter
Could you answer this?
What was 'Selective Availability' in GPS?
🛰️ Why Your Phone Needs Einstein
- 01Beeps From SpaceHow listening to Sputnik led to satellite navigation.
- 02Four Satellites and a StopwatchHow a phone works out where it is by timing radio signals.
- 03A Billionth of a SecondWhy GPS depends on atomic clocks and timing measured in nanoseconds.
- 04Einstein in OrbitThe relativity corrections that keep your blue dot on the right street.
- 05Lost in the CityUrban canyons, jamming and how your phone fills the gaps.