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What Affects GPS Accuracy?


In our modern era, it is an often overlooked, but impressive nonetheless, fact that we can measure distances and locations to within millimetres of true accuracy. If you consider the sheer amount of satellite systems, ground facilities, surveyors and equipment in use to make this possible, it is a true harmony of interconnected systems.

However, in spite of this, RTK GPS can still have issues with accuracy. Although they may be less significant or regular as older options, like dumpy levels or DGPS systems, it is possible that occasional dips in accuracy may be expected. So what is responsible for these inconsistencies and what can surveyors do to reduce the likelihood of them?

The Factors Affecting RTK GPS Accuracy


Ionospheric Delay

The ionosphere is one of the upper layers of Earth’s atmosphere, and it acts as a semi-physical barrier to the radio communication we use for interacting with our satellites. Understanding the nature of this delay is a relatively recent innovation, which is why you don’t typically see it included in DGPS devices. 

Satellite Clock Errors

RTK GPS also improves on the formula and accuracy of surveying equipment operations by accounting for satellite clock errors. We are all likely familiar with the expression “time is relative,” but it doesn’t really affect our daily lives. With satellite clocks, however, it is a critical consideration and one that humanity has yet to perfect.

Rover Distance

A surprisingly “dumb” problem with accuracy comes from the rover and base stations’ relative distance to one another. Range boosters are often employed for difficult or treacherous surveys to counteract the loss in accuracy that comes with increasing distance. 

Signal Interference

Although the technology and science behind these complex systems can make it seem like they work by some sort of magic, they are, in fact, working within some distinctly physical parameters. Therefore, one of the most common reasons for inconsistent data is signal interference from large objects. If the rover is in a valley without a GNSS receiver close at hand, there may be interference. This issue persists if doing work in modern settings as well.

Find Your RTK GPS Today

Although there may be problems with achieving the highest level of accuracy, millimetre level corrections are often of little consequence. If you are looking to improve your accuracy or replace an inaccurate piece of equipment, contact us today. We offer helpful advice and product information! 

Bench Mark Equipment & Supplies is your team to trust with all your surveying equipment. We have been providing high-quality surveying equipment to land surveyors, engineers, construction, airborne and resource professionals since 2002. This helps establish ourselves as the go-to team in Calgary, Canada, and the USA. Plus, we provide a wide selection of equipment, including global navigation satellite systems, RTK GPS equipment, GNSS receivers, and more. We strive to provide the highest level of customer care and service for everyone. To speak to one of our team today, call us at 403-286-0333 or email us [email protected]

About the Author

Nolan has been working in the surveying field since 2017, starting as a part-time student at Bench-Mark while attending the University of Calgary. He now works in technical support and sales helping customers find the right product for them.

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