Basics of GPS/QZSS/indoor positioning technology, accuracy improvement technology, and application examples

What is GPS?

Global Positioning System, or GPS, is a satellite-based navigation system that allows a GPS receiver to determine its precise location on Earth.
Initially developed by the United States Department of Defense, GPS was primarily intended for military use.
However, it has since become an indispensable tool for civilian applications, providing accurate positioning, navigation, and timing services to users all over the world.
The system relies on a constellation of at least 24 satellites orbiting the Earth, transmitting signals that a GPS receiver uses to calculate its exact position.

Components of the GPS System

The GPS system consists of three main components: space segment, control segment, and user segment.

1. Space Segment: This includes the 24 to 32 satellites orbiting the Earth.
The satellites are strategically positioned so that, at any time, a GPS receiver can access signals from at least four satellites.

2. Control Segment: This comprises monitor stations, master control stations, and ground antennas that maintain the satellites’ precise orbits and update their navigational data.

3. User Segment: This consists of GPS receivers that detect, decipher, and calculate location data from the satellite signals for various applications.

Introduction to QZSS

QZSS, or the Quasi-Zenith Satellite System, is a regional satellite navigation system created by Japan.
It is designed to augment GPS in Asia-Oceania, ensuring better coverage and improved accuracy because its orbits are optimized for better performance in urban and mountainous regions.
QZSS currently complements the existing GPS signals, providing additional data streams and enhancements to improve the accuracy of positioning for the area it covers.

How QZSS Works

QZSS features multiple quasi-zenith satellites that have orbits designed to linger over Japan and the Asia-Oceania region.
These satellites have higher positioning overhead than conventional satellites, offering enhanced signal reliability in areas where GPS signals languish, like in dense cities with tall buildings or deep valleys.
QZSS is also known as the “Michibiki” system, which means “guiding” in Japanese, reflecting its role in navigation and positioning.

Understanding Indoor Positioning Technology

While GPS and QZSS are excellent for outdoor navigation, their signals become weak or lost entirely when indoors.
Indoor positioning technologies address this gap, using various methods and technologies to determine a precise location within buildings or densely constructed areas.

Technologies for Indoor Positioning

1. Wi-Fi: Leveraging existing Wi-Fi networks, devices can determine their position by analyzing the signal strengths from multiple access points. The precision of Wi-Fi-based systems can range from 2 to 15 meters, depending on network density and other factors.

2. Bluetooth Beacons: These are small, low-energy devices that broadcast signals to nearby devices. By measuring signal strength from several beacons, a device can triangulate its location. Bluetooth beacons typically offer higher accuracy compared to Wi-Fi.

3. Ultra-Wideband (UWB): UWB technology offers precise location-finding capabilities by measuring the time it takes for signals to travel between beacons and devices. It provides accuracy within centimeters, making it excellent for applications requiring high precision.

4. Magnetic Positioning: This method uses distortions in the Earth’s magnetic field caused by indoor structures to pinpoint a location. It generally requires a pre-mapped environment.

Accuracy Improvement Techniques

Ensuring precise positioning not only avoids errors but also enhances the reliability of navigation systems.
Several techniques help improve the accuracy of positioning technologies.

Differential GPS (DGPS)

DGPS enhances GPS accuracy by using a network of fixed ground-based reference stations.
These stations provide the GPS receivers with correction data to reduce positioning errors, offering improved accuracy compared to conventional GPS.

Assisted GPS (A-GPS)

A-GPS helps speed up location acquisition by providing additional data through a mobile network or the internet.
It combines satellite and network data, reducing the time-to-first-fix and enhancing positioning accuracy—especially useful for mobile phones.

Augmentation Systems

Satellite-based augmentation systems (SBAS) like the European Geostationary Navigation Overlay Service (EGNOS) or the Wide Area Augmentation System (WAAS) correct GPS errors, improving accuracy and integrity, particularly for aviation and other professional uses.

Application Examples of Positioning Technologies

Positioning technologies are widely applied across numerous domains, offering varied benefits.

Navigation and Mapping

GPS and QZSS are fundamental in navigation applications, from car navigation systems to geolocation-based services in smartphones.
They enable accurate mapping and routing, crucial for logistics, travel, and personal navigation.

Sustainable Agriculture

Precision agriculture employs GPS-based technologies for soil sampling, crop monitoring, and equipment navigation.
The accurate data ensures optimized resource use, enhancing productivity, and reducing environmental impact.

Search and Rescue Operations

GPS enables effective search and rescue operations by providing rescuers with the exact locations of distress signals.
This capability can significantly reduce response time and increase the likelihood of successful missions.

Fitness and Health Apps

Positioning technology underpins many fitness and health applications that track movements and routes, which is crucial for activities like running, cycling, and hiking.
These apps provide users with data insights about their physical activities, aiding in performance tracking and improvement.

IoT and Smart Cities

Indoor positioning technologies are part of the Internet of Things (IoT) solutions for smart cities.
They aid in facilities management, asset tracking, and navigation within large infrastructures like shopping malls, airports, and hospitals.

Positioning technologies continue to evolve, providing unprecedented capabilities for accurate location data across various environments.
Understanding the fundamentals of GPS, QZSS, and indoor positioning, as well as techniques to enhance accuracy, is essential to linearly advance in technology applications across different industries.
As these systems improve, they promise to provide seamless navigation, greater efficiency, and enhanced safety in our everyday lives.