Global Navigation Satellite Systems (GNSS) Cheat Sheet

GNSS is a satellite-based system providing global positioning, navigation, and timing (PNT) services. It encompasses various satellite constellations like GPS, GLONASS, Galileo, and BeiDou, each with unique characteristics and applications.

Core Principles

• GNSS provides precise location, velocity, and time information globally.
• It relies on a constellation of satellites orbiting Earth.
• Receivers on the ground calculate position by measuring signals from multiple satellites.
• Key GNSS constellations include GPS (USA), GLONASS (Russia), Galileo (EU), and BeiDou (China).
• Regional Navigation Satellite Systems (RNSS) offer localized coverage.
• Different satellite orbits (LEO, MEO, GEO) impact latency and coverage.
• GNSS technology has evolved significantly, with continuous improvements in accuracy and capabilities.
• Applications span numerous fields, including transportation, surveying, agriculture, and emergency services.

Action Steps

• Understand the fundamental concept of satellite-based positioning.
• Identify the major GNSS constellations and their origins.
• Differentiate between GNSS and RNSS.
• Recognize the various satellite orbits and their implications.
• Explore the historical development and future trends of GNSS.
• Consider the diverse applications of GNSS across different industries.
• Be aware of potential limitations and challenges associated with GNSS usage.

Key Terms

• GNSS: Global Navigation Satellite System: A general term for satellite systems providing positioning, navigation, and timing services globally.
• GPS: Global Positioning System: The U.S.-operated GNSS, widely used and often colloquially referred to as GNSS.
• GLONASS: Global Navigation Satellite System: The Russian GNSS.
• Galileo: The European Union's GNSS.
• BeiDou: The Chinese GNSS.
• RNSS: Regional Navigation Satellite System: Provides navigation services within a specific geographic region.
• LEO: Low Earth Orbit: Satellites orbiting at altitudes of 500-2000 km, offering low latency.
• MEO: Medium Earth Orbit: Satellites orbiting at altitudes of 2,000-34,000 km.
• GEO: Geostationary Earth Orbit: Satellites orbiting at an altitude of approx. 35,786 km, appearing stationary relative to a point on Earth.
• PNT: Positioning, Navigation, and Timing: The core services provided by GNSS.

Pro Tips

• Always check the number of visible satellites for optimal accuracy.
• Understand the difference between standard and precise positioning services.
• Consider atmospheric conditions and their potential impact on signal accuracy.
• Integrate GNSS data with other sensors for enhanced performance.
• Stay updated on new GNSS signals and augmentation systems.

Pitfalls to Avoid

• Using 'GPS' as a generic term for all GNSS.
• Over-reliance on GNSS in environments with signal obstruction (indoors, tunnels).
• Ignoring potential signal errors, biases, and interference.
• Misinterpreting accuracy levels for different receiver types.
• Assuming all GNSS systems are identical in performance.

Myth vs Reality

• GPS is the only Global Navigation Satellite System.: GPS is one of several GNSS, alongside GLONASS, Galileo, and BeiDou, each operated by different countries or regions.
• GNSS signals are always perfectly accurate.: GNSS signals can be affected by atmospheric conditions, signal obstructions, multipath effects, and intentional interference, leading to potential inaccuracies.
• All GNSS receivers are the same.: GNSS receivers vary significantly in type (navigation, mapping, geodetic), accuracy, features, and cost, depending on their intended application.

Real World Examples

• A hiker uses a smartphone app to navigate a trail.: Smartphone GNSS receivers provide location data for navigation apps.
• Surveyors map a construction site.: Geodetic GNSS receivers offer high precision for accurate land surveying and mapping.
• An airplane follows its flight path.: Aircraft navigation systems rely on GNSS for precise positioning and guidance.
• A ship navigates international waters.: Marine navigation systems use GNSS for safe and efficient passage.

Statistics

• Number of GPS operational satellites (as of July 3, 2023): 31
• Number of GLONASS operational satellites (as of August 2020): 23
• Number of Galileo operational satellites (planned): 30
• Number of BeiDou operational satellites (as of 2023): 46

Timeline

• ~1760: Astronomy and Geodesy used for latitude, limited for longitude until accurate clocks.
• 13th Century: Development of the Magnetic Compass.
• 1907: Invention of the Gyrocompass.
• 1912: Radio Direction Finding systems emerge.
• 1930s: Radar and Inertial Navigation Systems (INS) developed.
• 1940s: Loran-A navigation system introduced.
• 1960s: Omega and Doppler Satellite systems developed.
• 1970s: Loran-C navigation system introduced.
• 1978: First GPS satellite launched.
• 1980s: GPS and GLONASS systems begin development.
• December 1993: Initial GPS service declared.
• September 1993: Initial GLONASS service declared.
• 2000: First BeiDou satellite launched.
• December 2012: BeiDou system officially operational.
• 2011: First Galileo satellite launched.
• 2016/2017 (planned): Initial Galileo service.
• 2000s onwards: Development and deployment of multiple GNSS constellations.
• 2013: First IRNSS satellite launched.
• 2010: First QZSS satellite launched.
• 2016: Galileo Initial Services begin.
• 2020: Full Operational Capability for Galileo planned.

People

• Fendra D. Ramadhan: Lecturer (Dosen Pengajar)
• Rizki W. Pratama: Lab Assistant (Laboran)
• Hasanuddin Z. Abidin: Author/Researcher (cited in references)
• Andrew Jones: Author/Researcher (cited in references)
• Joenil Kahar: Author/Researcher (cited in references)
• Chris Rizos: Author/Researcher (cited in references)
• Günter Seeber: Author/Researcher (cited in references)