What Is a GPS Sensor?
A GPS sensor is a device used in the Global Positioning System (GPS), a worldwide satellite-based positioning system. GPS operates continuously, providing high-accuracy location measurements for various applications such as car navigation, time synchronization, and geophysical observations.
Uses of GPS Sensors
Initially used in aircraft, ships, and surveying, GPS sensors have found widespread use in today’s information technology era. They are actively incorporated into smartphones, laptops, car navigation systems, digital cameras, smartwatches, and drones. GPS sensors also play a crucial role in precision surveying and measuring crustal deformation to mm or cm levels. Additionally, GPS satellites help synchronize time data measured by international atomic clocks for determining international standard time.
Principles of GPS Sensors
GPS sensors determine their position on Earth by measuring the distance to multiple satellites. The L1 and L2 signals emitted from these satellites are detected by GPS receivers, which calculate the time difference between signal transmission from the satellite and reception on Earth. Since these radio waves travel at the speed of light, the time of travel multiplied by the speed of light gives the distance between the satellite and the GPS sensor on the ground.
Other Information on GPS Sensors
1. Operation of GPS Satellites
GPS satellites transmit L1 and L2 signals at specific times. The ground control monitors the satellites’ time and orbit, managing signal transmission and reception. Most ground control stations are unmanned, except for the main station.
2. Number of GPS Satellites
For accurate positioning, information from at least four GPS satellites is typically used to compensate for the less accurate clocks in GPS receivers compared to the atomic clocks in the satellites.
3. Accuracy of GPS
GPS sensors in smartphones and car navigation systems generally offer an accuracy of several meters. Efforts to enhance accuracy include combining GPS data with WIFI base station distances, electronic compasses, and other technologies. The broader term for satellite-based positioning systems like GPS is GNSS (Global Navigation Satellite System), which includes systems like QZSS (Quasi-Zenith Satellite System).
4. RTK Technology
RTK (Real Time Kinematic) is a method that enhances GPS accuracy by using two receivers—a reference base station and a mobile station—to compensate for positional deviations. This can improve accuracy to a few centimeters, making it promising for use in smartphones and drones. When combined with ICT (information and communication technology), RTK opens up possibilities for new services like smart agriculture, construction, and drone delivery.
5. GPS Transmitters
GPS transmitters calculate location from GPS signals and transmit this information to specific destinations. They can be used for real-time tracking or manual searching, with applications ranging from monitoring the elderly and children to theft prevention for vehicles and personal items and ensuring safety in outdoor activities.