3.4.5. Advantages and disadvantages of GNSS

• It is easy to navigate with GPS.
• It is available 24 hours anytime.
• It has world coverage.
• It is independent of weather conditions.
• It is independent of visibility conditions: night, fog and dust.
• It has open signal.
• It requires open to sky clearance.
• It is faster and quicker, particularly where Total Station can’t be used due to horizontal obstructions.
• Multi-constellations and multi-frequency receivers can provide much accurate results.
• It is independent of visibility of previous points, as all measurements are independent.
• Its data can be easily integrated with Total Station data and GIS.

The advantages of GNSS (Global Navigation Satellite Systems) are significant. First, it simplifies navigation, as GPS devices provide direct routes and real-time guidance. Availability 24/7 means users can navigate at any time, which is crucial for various activities, from driving to hiking. The world coverage assures users that they can receive signals globally, making it useful for international travel.

Another key advantage is its reliability irrespective of weather conditions. GNSS can operate through rain or fog, which would hinder other navigation systems. Availability of an open signal allows easy access to GNSS data, ensuring widespread usage without restrictions, although a clear view of the sky is necessary to receive signals effectively. Moreover, GNSS is faster, particularly in challenging environments where other surveying methods, like Total Stations, may be obstructed.

Advancements in technology have led to multi-constellation and multi-frequency receivers, enhancing accuracy and reliability of positioning solutions. Each GNSS measurement is made independently, which allows integration with other technologies such as Total Station and Geographic Information Systems (GIS). This integration significantly improves the efficiency of data collection and analysis.

Think of using GNSS like having a global map available on your smartphone that updates in real-time as you move. Just like the map shows your current location and offers directions to your desired destination, GNSS works tirelessly 24/7, allowing anyone with a device to navigate the world with ease. Whether you're hiking in a mountainous area or driving through a city at night, GNSS remains reliable, guiding you without concern for weather conditions or time of day.

• A good visibility for the sky is necessary, as high rise buildings obstruct the signals.
• It can’t be used for indoor positioning.
• It can’t give precise results in areas like, forest, under a bridge, tunnel, etc.
• Vertical precision is not enough for some applications.
• Extreme atmospheric conditions, storms can contribute to errors in GPS observations.
• With limited number of satellites, accurate results may not be obtained.

Despite its advantages, GNSS also has drawbacks that can limit its effectiveness. First, the system requires a clear view of the sky; thus, tall buildings, trees, or overhanging structures can obstruct the signals, leading to inaccurate positioning or complete signal loss. This challenge makes GNSS unsuitable for indoor navigation as signals cannot penetrate walls.

Furthermore, GNSS struggles in densely vegetated areas or urban canyons, like under bridges or in tunnels, where GPS signals are significantly weakened. Users may also experience issues with vertical precision, as the technology is less reliable in measuring altitude compared to horizontal position.

Another disadvantage is that extreme weather conditions, such as storms, can introduce errors in GNSS observations, affecting accuracy. Lastly, the dependency on the number of satellites in view means fewer satellites can lead to poor positioning solutions, making it crucial to have as many visible satellites as possible for precise location accuracy.

Imagine trying to get a GPS signal inside a tunnel or beneath a tall building. It's akin to relying on a radio that cuts out during stormy weather; just like you can't hear the station clearly if obstructions get in the way, the GNSS system struggles to determine your precise location when the signals are blocked or interfered with. This situation highlights the limits of technology—having a powerful device like a GNSS does not guarantee perfect performance in every environment.

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