What Is the Difference Between Terrestrial and Satellite AIS Tracking?
Tracking ships worldwide relies on AIS (Automatic Identification System), a technology that transmits vessel identity, position, speed, and voyage details. But not all AIS data is received the same way. Two major systems deliver AIS signals globally: Terrestrial AIS and Satellite AIS.
Understanding the difference between these technologies is essential for maritime professionals, ship spotters, fleet managers, logistics companies, and anyone who uses real-time vessel tracking apps like Marine Radar: Vessel Tracker.
This guide explains how both AIS tracking systems work, their strengths and limitations, and why combining both offers the most accurate marine tracking experience.
What Is AIS Tracking?
AIS tracking is the process of receiving real-time vessel information transmitted from onboard AIS transponders. AIS signals are captured either by coastal receiving stations (terrestrial) or orbiting satellites (satellite AIS).
Each vessel broadcasts data, including,
- IMO Number
- MMSI Number
- Vessel Name
- Position (Latitude & Longitude)
- Speed & Course
- Destination & ETA
- Type, Size & Dimensions
- Navigational Status
What Is Terrestrial AIS?
Terrestrial AIS (T-AIS) refers to AIS signals captured by land-based receivers installed along coastlines, ports, and islands.
How It Works
Vessels transmit AIS signals; shore-based receivers pick up signals, which are then processed and displayed on marine tracking systems like the Marine Radar app.
Coverage
- Up to 40–70 nautical miles from the coastline
- Depends on elevation, weather, and radio interference
Advantages of Terrestrial AIS
- Low latency (near real-time)
- High refresh rate, frequent updates
- Strong accuracy in coastal waters
Limitations of Terrestrial AIS
- No visibility in the open ocean
- Coverage is weak in remote areas
- Dependent on physical infrastructure
What Is Satellite AIS?
Satellite AIS (S-AIS) captures signals from vessels using orbiting satellites equipped with AIS receivers.
How It Works
Ships transmit AIS; the signal is received by satellites passing overhead and transmitted to tracking platforms, such as the Marine Radar app.
Coverage
Global, including:
- Deep ocean routes
- Remote seas
- The polar region
- Far offshore areas beyond VHF range
Advantages of Satellite AIS
- Worldwide coverage
- Ideal for long-distance shipping & ocean crossings
- Helps track vessels in unmonitored, isolated regions
Limitations of Satellite AIS
- Refresh rate depends on satellite positions
- Signal collision in high-traffic areas
- Slightly higher latency than terrestrial AIS
Terrestrial vs Satellite AIS: Key Differences
The Marine Radar: Vessel Tracker app integrates both Terrestrial AIS & Satellite AIS to deliver complete global visibility.
How Does Marine Radar Use Both Systems for Better Tracking?
The Marine Radar: Vessel Tracker app integrates both Terrestrial AIS & Satellite AIS to deliver complete global visibility.
- Real-Time Coastal Tracking (Terrestrial AIS)
Marine radar uses high-density terrestrial stations to provide rapid updates near ports and coastlines.
- Global Open Ocean Coverage (Satellite AIS)
Satellite AIS ensures you can track vessels anywhere in the world, even across remote oceans.
- Accurate Vessel Profiles with IMO + MMSI
Marine Radar combines AIS data with:
- IMO Numbers
- MMSI Numbers
- Call Sign
- Ownership details
- Flag
- Voyage & ETA
- Vessel type & size
- Enhanced Map Intelligence
Marine Radar map features include:
- Nearby vessel finder
- Map style customization
- Route replay
- Area statistics by country/region
- Ship density heatmaps
- Alerts & Notifications
Using AIS data, Marine Radar offers:
- Arrival & departure alerts
- Position-change alerts
- Course-change alerts
- Speed-change alerts
Which AIS Tracking Method Is Better?
It depends on your need:
- For Coastal Tracking → Terrestrial AIS
Ideal for port authorities, pilot boats, harbor operations, and local ship spotting.
- For Long-Distance Tracking → Satellite AIS
Perfect for tracking vessels on international routes, deep-sea shipping, and cargo monitoring.
- For Complete Tracking → Both Combined (Marine Radar)
Marine Radar combines both datasets to provide the most comprehensive ship tracking experience.
Conclusion
Both terrestrial AIS and satellite AIS are essential for global vessel tracking. While terrestrial AIS provides quick, near-shore accuracy, satellite AIS delivers global ocean coverage.
Marine Radar intelligently merges both, giving users the ability to track any vessel, whether coastal or deep-sea, in real time.
For maritime professionals, logistics firms, and ship enthusiasts, understanding these two AIS systems helps clarify how marine radar provides such accurate and reliable vessel data worldwide.
FAQs
- What is the main difference between Terrestrial and Satellite AIS?
Terrestrial AIS utilizes land-based receivers, whereas satellite AIS employs satellites to capture vessel signals worldwide.
- Which AIS tracking system is more accurate?
Terrestrial AIS provides more frequent updates near the coast, while satellite AIS offers global tracking even when vessels are far offshore.
- Does marine radar use both AIS types?
Yes. Marine Radar utilizes a hybrid system that combines terrestrial AIS and satellite AIS for comprehensive global visibility.
- Can Satellite AIS track a ship anywhere?
Yes. Satellite AIS covers all oceans, including remote routes that extend beyond the range of terrestrial receivers.
- Why does AIS sometimes show delayed updates?
Satellite passes, signal collisions, atmospheric conditions, and AIS transponder strength can affect update frequency.
