Satellite Navigation (satnav) is a system of satellites that provide longitude, latitude, and elevation measurements. Satellite systems rely on the global coverage of satnav’s geo-spacial positioning and satellite constellations to receive location information for outdoor asset tracking applications for fleets of vehicles, sea vessels, industrial machinery, and more. Often mistakenly used interchangeably, GPS and GNSS have nuanced differences. GNSS refers to the totality of satellite navigation systems, whereas GPS is constellation specific. Correct nomenclature is critically important when selecting a satellite receiver module for an end product design.
What Does GPS Stand For?
Originally introduced by the US military in the 1960s, GPS (Figure 1) specifically stands for Global Positioning Systems and provides navigation resources to the ground location of objects and assets. The United States has 31 GPS satellites, NAVSTAR, that emit signals to enable receivers to determine ephemeris data. Ephemeris data provides GPS receivers with information regarding an object’s location, timing, and health in relation to satellites in orbit. Ephemeris data can also be utilized as a GPS data collection scheduling tool as it provides future predictions of satellite conditions.
A Grand View Research report predicts that “The global positioning systems (GPS) market size is anticipated to reach USD 146.4 billion by 2025.” There are many factors that can affect the accuracy of GPS data as it is a line-of-site technology. Satellite geometry, physical obstacles, atmospheric conditions, and type/quality of GPS receiver can inhibit data accuracy. Additionally, data collected through GPS may be accurate, but the software interpreting the data may provide inaccuracies like mislabeled or missing roads. However, standard GPS service providers generally provide users with accuracy within 7 meters, 95% of the time.
Figure 1: GPS architecture
Source: Federal Aviation Administration
What Does GNSS Stand For?
GNSS is an acronym for Global Navigation Satellite System and refers a constellation of satellites that provide positioning and timing transmission to enabled receivers. While the term GPS technically refers specifically to the United States satellite constellation, GNSS includes GPS, the European constellation (Galileo), the Russian Constellation (GLONASS), China’s BeiDou Navigation Satellite System, and others. Most modern GNSS modules utilize and track several different satellite constellations. A designer might be disappointed if they choose a “GPS module” that ONLY supports a single constellation.
Like GPS technology, GNSS architecture is broken into three segments (Figure 2); the space segment, the control segment, and the user segment. GNSS performance is analyzed by the following factors:
Accuracy
Integrity
Continuity
Availability
Figure 2: GNSS architecture is comprised of three segments
Source: European Space Agency Navipedia
Differences Between GPS and GNSS:
To be clear, GNSS is an umbrella term for global satellite positioning systems. GPS is a type of GNSS and can be used in conjunction with other GNSS constellations. Choosing a satellite receiver module with support for multiple GNSS constellations provides maximum flexibility in establishing a quick and accurate location fix. This is especially helpful when line-of-site is obstructed to one or more of the satellites within GNSS constellations.
GPS and GNSS are related, but are not synonymous terms. If you are looking at which technology to incorporate into your design, contact our engineering experts at Connected Development for assistance on your next product development.