Why GNSS Performance Changes in Different Environments

The same GNSS receiver can deliver very different performance depending on where it is used - sometimes varying by several times or even an order of magnitude.

In open sky, positioning may appear extremely stable.
In cities, RTK may struggle to fix.
Near water, data may look stable but still contain hidden errors.

Many users assume this is a device issue.
In reality, GNSS performance is primarily determined by the environment.

Why GNSS Performance Varies

GNSS signals travel over 20,000 kilometers from satellites to Earth. During this journey, they are highly sensitive to environmental conditions near the receiver.

Three key factors dominate GNSS performance:

• Signal obstruction
• Multipath effects
• Signal quality (SNR and geometry)

These factors determine whether a receiver can maintain stable and accurate positioning.

Key Factors Affecting GNSS Performance

1. Signal Obstruction

Obstacles such as buildings, trees, and terrain can block or weaken satellite signals.

Effects include:

• Reduced the number of visible satellites
• Lower signal quality (SNR)
• Difficulty achieving RTK fixed solutions

Obstruction is one of the main causes of unstable positioning in urban environments.

2. Multipath Effects

Multipath occurs when GNSS signals reflect off surfaces such as:

• Buildings
• Roads
• Water
• Metal structures

The receiver then processes both direct and reflected signals, leading to distorted measurements.

This is especially severe in urban canyon environments, where signal reflections are constant and complex.

3. Signal Quality and Geometry

GNSS performance is also affected by:

• Signal-to-Noise Ratio (SNR)
• Satellite geometry (DOP values)

Poor satellite distribution or weak signals reduce positioning stability and accuracy, even in partially open environments.

Environment Comparison

Urban Environment

Urban areas are not signal-poor—they are signal-complex.

Characteristics:

• Heavy obstruction from buildings
• Strong multipath reflections
• Poor satellite geometry (urban canyon effect)

Result:

• Difficulty achieving RTK Fix
• Large positioning fluctuations
• Reduced reliability

Riverside Environment

Water surfaces create strong signal reflections.

Characteristics:

• Open sky visibility
• Strong reflective surfaces (water)

Result:

• Appears stable
• Contains hidden multipath errors
• Position bias may exist without obvious fluctuations

Open-Sky Environment

This is the ideal GNSS environment.

Characteristics:

• Minimal obstruction
• Low multipath
• Good satellite geometry

Result:

• Highest accuracy
• Most stable positioning

However, this represents ideal conditions—not typical real-world scenarios.

Conclusion

GNSS performance is not defined only by the receiver—it is fundamentally shaped by the environment.

Obstruction, multipath effects, and signal quality together determine positioning stability and accuracy.

Understanding these factors is more important than assuming GNSS performance should remain constant across all locations.

In real-world applications, the environment always defines GNSS performance.

📘 Recommended Reading

Want to understand why GNSS positions drift even when the receiver is stationary?

👉 Why Does GNSS Position Drift When the Receiver Is Stationary?

A deep dive into measurement noise, multipath, and satellite geometry effects.