GPS

GPS (Global Positioning System) is a global satellite navigation and timing system developed and maintained by the United States Department of Defense, representing the world's first fully operational commercial Global Navigation Satellite System (GNSS). Comprising three major segments—the space constellation, ground control system, and user receivers—it provides all-weather, high-precision 3D positioning, velocity, and standard time reference services globally (excluding polar regions) and in near-Earth space. In the modern automotive industry, GPS serves as an essential core technology for in-car navigation, telematics connectivity, high-precision positioning for autonomous driving, and vehicle anti-theft tracking systems.

Core Technical Architecture and Operating Principles

The technical architecture of GPS primarily consists of a Medium Earth Orbit (MEO) satellite constellation, ground control and monitoring stations, and in-vehicle GNSS receiver modules:

Space Constellation Multi-Point Deployment and Pseudo-Random Ranging Codes (Orbital Constellation Deployment and Pseudo-Random Ranging Codes):

The GPS space constellation typically comprises at least 24 operational satellites distributed across six orbital planes at an altitude of approximately 20,200 kilometres. Each satellite continuously broadcasts radio signals containing its precise orbital ephemeris and atomic clock data, embedded with dedicated pseudo-random noise codes (such as the C/A code). The on-board receiver captures these signals to compute the precise time-of-flight of the radio waves travelling from the satellites to the vehicle antenna. 

3D Spatial Intersection Ranging and Four-Satellite Joint Resolution (3D Spatial Intersection Ranging and Four-Satellite Joint Resolution):

In-car navigation receivers utilise the principle of trilateration by simultaneously locking onto signals from at least four GPS satellites to solve a system of four mathematical equations. Three satellites determine the vehicle's 3D latitude, longitude, and altitude within the Earth coordinate system, while the fourth satellite corrects the clock bias between the vehicle's quartz clock and the satellite atomic clocks, delivering accurate real-time position and speed readouts. 

Safety Guidelines and Physical Limitations 

Strict Prohibition of Sole Reliance on GPS in Dense High-Rise Areas, Long Tunnels, Under Flyovers, or During Strong Electromagnetic Interference (Prohibiting Blind Reliance on Single GPS Positioning in Dense Urban Canyons, Long Tunnels, Under Overpasses, or During Strong Electromagnetic Interference):

GPS satellite signals are inherently weak and easily obstructed by high-rise buildings, heavy concrete decks, or challenging terrain, resulting in severe multipath errors or total signal loss (blind spots). Drivers and autonomous systems must never rely solely on drifted or interrupted GPS coordinates in extreme environments without redundant backup systems—such as high-definition (HD) maps, Inertial Measurement Units (IMU), or wheel speed sensors—to avoid taking wrong lanes or causing traffic accidents. 

Strict Prohibition of Unauthorised In-Vehicle GPS Signal Jammers or High-Power Interference Equipment (Prohibiting Unauthorized Use of Illegal Vehicle GPS Signal Jammers or High-Power Interference Equipment):

While some motorists attempt to use portable GPS jammers to protect privacy or evade fleet tracking, these radio frequency jamming devices severely disrupt road traffic monitoring, telematics emergency response services, and the navigation systems of neighbouring vehicles. Installing or operating GPS jamming or spoofing equipment in any vehicle or on public roads is strictly prohibited, and offenders will face severe legal prosecution and regulatory penalties.