GNSS vs GPS: Examining the Differences


Modern technology has revolutionized the surveying industry, making it possible to achieve more accurate readings than ever. Not only is it possible to measure angles and distances with greater accuracy, but some technology, specifically global positioning system (GPS) technology, negates the need for these measurements entirely.

The surveying and mapping industry was among the first to use GPS technology - it is much faster, more accurate, and requires less manpower than conventional surveying methods. Here is what you need to know about GPS technology and how it differs from GNSS.

What Does GNSS Stand For?

Modern navigation technology has become part of everyday life and is widely used in a variety of industries to improve efficiency and accuracy. When it comes to navigation, however, the average layman only knows the term GPS. As a surveyor, you understand that the term global positioning system or GPS is a specific system within a larger category.

The term GNSS stands for Global Navigation Satellite System and it is an umbrella term that covers all global satellite positioning systems. GPS is the most widely used GNSS system in the world, originally developed for military use but now accessible to civilians.

The only other fully operational global navigation system is GLONASS, a Russian GNSS. However, there are four GNSS systems in various stages of development:

  • Galileo - the European Union’s positioning system
  • IRNSS - India’s next-generation regional navigational satellite system
  • QZSS - Japan’s regional system
  • Beidou - China’s global navigation satellite system

Satellite navigation has a wide variety of applications, used on both a national and international scale. GNSS systems are useful in any field where precise timing and positioning information is required. This includes the fields of transportation, agriculture, vehicle navigation, marine navigation, mobile communications, and even athletics.

What is the Difference Between GNSS and GPS?

GNSS technology is used in conjunction with existing GPS systems to determine precise location positioning anywhere on the planet. Though both global navigation systems work together, GNSS equipment works on a larger scale. GNSS-compatible equipment can utilize signals from navigational satellites in networks outside the GPS system.

Both GNSS and GPS consist of three primary segments:

  • Satellites - The space segment
  • Ground Control Stations - The ground segment
  • Receivers - The user segment (GPS or GNSS)

Satellites send continuous radio signals toward earth, picked up by GPS and GNSS receivers. The ground control stations that monitor the GNSS track the satellites, updating their positions so information can be transmitted from earth back to the satellites.

How Accurate is GNSS?

Global positioning system technology makes it possible to accurately pinpoint a location using satellite signals. The trouble with GPS is that it only uses satellites owned and run by the United States. These satellite signals are limited - they can easily be blocked by bad weather or geographical obstacles like mountains. If too many of the signals are blocked, a GPS receiver becomes useless until the signal can be reestablished.

Global navigation satellite system technology operates on a broader scale, using signals from any navigation satellite, not just GPS. More signals equate to increased accuracy and reliability. All GNSS receivers are GPS-compatible, but not all GPS receivers are GNSS-compatible.

How is GPS Used in Surveying?

The GPS used in the surveying industry is more complex than the satellite navigation technology common to everyday life. GPS receivers have high-quality antennas and use two frequencies to establish a GPS baseline - one receiver is placed at either end of the line being measured. Data is collected from the same satellites at the same time and later compared to determine the difference in latitude, longitude, and height between the two points.

The benefit of GNSS technology in the surveying field is freedom from physical constraints. Using global navigation satellite system technology, surveyors are not limited by line-of-sight visibility. Survey stations can be placed anywhere with an open view of the sky, no longer confined to remote hilltops within sight of another station.

Global positioning technology is particularly beneficial in areas where there are few land-based reference points. When surveying coasts and waterways, sonar depth soundings can be combined with GPS positions to create nautical charts. This technology is also useful for offshore oil rigs and bridge builders to create accurate hydrographic surveys.

GPS Equipment for Surveyors

Accuracy in the surveying industry all comes down to the quality of your equipment. Most GPS receivers for surveyors use two radio frequencies: L1 and L2. At this time, however, there is no fully functional civilian signal on the L2 frequency. As a result, many receivers leverage a military L2 signal by using a codeless technique.

In addition to receivers, surveyors utilize a variety of GPS rover rods, poles, tripods, and antennae for mounting equipment. Depending on how much equipment your team requires, the price of a GPS surveying system varies. You can expect to pay $4,000 to $10,000 per receiver with an additional cost of $400 or more for the software itself.

The development of the global positioning system changed the land surveying industry for the better, improving efficiency, accuracy, and convenience. As new technology is developed, these improvements will become compounded and the industry will continue to advance.

What you need to know about GPS technology and how it differs from GNSS.