GPS and GNSS
Global Navigation Satellite System (GNSS) is used to determine a drone's position on Earth. GPS is a specific type of GNSS.
GNSS
Global Navigation Satellite System: consists of 89 satellites, ground based station, aircraft receiver
PRN Code: radio signal sent from satellites to user device. It has timestamped data that has distance calculations which is decoded by a GNS receiver.
Signal Error Causes: reflected, refracted, obstructed, not enough satellite signals.
Post-Processed Kinematic (PPK): is a GNSS data correction technology which is widely used in surveying and mapping to obtain high-precision positioning data or centimeter-level accuracy.
It is mainly used in drone mapping and can also be used as a backup for Real-Time Kinematic technology in surveying projects.
Image Source: https://www.eenewseurope.com/en/global-and-easy-access-to-satellite-l-band-gnss-corrections/
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GPS
Global Positioning System: Consists of 30 satellites orbiting the earth 11,000 nautical miles above the Earth.
GPS Signals: travel at the speed of light, distance measured in time
GPS Satellites: 3 are needed to triangulate your position (can be off by 2 metres); 4 can more accurately read your position.
Real-Time Kinematic (RTK): is a technique that uses carrier-based ranging and provides ranges (and therefore positions) that are orders of magnitude more precise than those available through code-based positioning. (mainly used to correct location)
With reference to GPS in particular, the system is commonly referred to as carrier-phase enhancement, or CPGPS. It has applications in land survey, hydrographic survey, and in unmanned aerial vehicle navigation.
Image Source: https://www.eenewseurope.com/en/global-and-easy-access-to-satellite-l-band-gnss-corrections/
Image Source: https://www.dronerush.com/drone-gps-10778/