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System Redundancy

Beyond GPS

By Tim Bartlett

The fact that onboard positioning systems may be able to use signals from more than one system may improve performance for all. Here are four advantages to a truly global satellite-navigation system:

  1. Integrity: If overall control is not in the hands of one state, the chances of service being denied by the provider or the system being disrupted by an attacker are reduced.
  2. Precision: In a combined multiconstellation system, the higher number of satellites available to the user will allow receivers more opportunities to select the satellites that give the best fix. Some estimates suggest that this will dial in position-fixing accuracy to inches, rather than feet.
  3. Availability: Increasing the number of satellites will improve the availability of the signals especially in high-rise cities, where buildings can obstruct signals from satellites that are low on the horizon.
  4. Coverage: The location and inclination of its satellites means that GPS is optimized for coverage around the Equator and middle latitudes: Galileo and GLONASS are optimized for coverage at higher latitudes.