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Components and How an AIS Receiver Works in a Vessel Tracking System
Posted on May 26, 2026 by Nur Wachda Mihmidati
An AIS receiver is a device used to capture Automatic Identification System (AIS) signals from nearby vessels and convert them into real-time navigation data. This system operates passively without transmitting any signals back, making it commonly used for vessel traffic monitoring, navigation safety, and port operations oversight. Read the full explanation in the following TransTRACK article!
What is an AIS receiver?
An AIS receiver is a device used to receive signals from the AIS (Automatic Identification System) transmitted by vessels in the surrounding waters.
The Automatic Identification System is a maritime communication system that automatically transmits important vessel data such as:
- Vessel identification (name, MMSI)
- GPS Location
- Speed and direction
- Navigation status (sailing, anchored, etc.)
How Does an AIS Receiver Work?
Here is a step-by-step explanation of how an AIS Receiver (Automatic Identification System Receiver) works, from signal reception to display on the screen:
The Automatic Identification System operates by using VHF radio waves to transmit and receive real-time vessel position data.
1. VHF Frequency List (AIS Channels)
AIS operates on two main VHF channels:
- Channel 87B (161.975 MHz) Used for AIS transmissions (AIS 1)
- Channel 88B (162.025 MHz) Used for AIS transmissions (AIS 2)
Directions for use:
- Both of these channels operate using time-division multiple access (TDMA)
- The ships do not experience “signal interference” because the time slots are automatically assigned
- The receiver alternately picks up signals from both frequencies to improve coverage
2. Data Decoding List (Signal → Digital Data)
Steps in AIS data conversion:
a. Signal Reception
- The AIS receiver picks up raw VHF radio signals from nearby vessels
b. Demodulation
- Radio signals are converted into digital bits (0s and 1s)
c. Parsing NMEA Sentence
- Digital data is converted into a standard format:
- NMEA 0183 sentence (example: !AIVDM,1,1,,A,…)
d. Decode Information
From the NMEA data, the system extracts:
- MMSI (vessel identification)
- Latitude & Longitude
- Speed Over Ground (SOG)
- Course Over Ground (COG)
- Navigation status
3. Visualization List (Data Output)
Once the data has been successfully decoded, the information is displayed across various platforms:
a. Chartplotter (Marine Navigation Display)
- Displaying the ship’s position on a nautical chart
- Used on ship bridges or in professional navigation systems
b. Radar / ECDIS System
- Combining AIS and radar for situational awareness
- Display the target vessel as an “overlay” on the navigation screen
c. PC / Software Monitoring
- Apps like OpenCPN, Coastal Monitoring System, or port platforms
- Used for fleet tracking and traffic monitoring
d. Mobile Apps / Cloud Platform
- Real-time visualization on a smartphone or cloud-based dashboard
- Commonly used for fleet management and port surveillance systems
The Difference Between an AIS Receiver and an AIS Transponder
In the Automatic Identification System (AIS), onboard devices are generally divided into two main categories based on their function: devices that only receive data and devices that also transmit data. This distinction directly affects a vessel’s visibility, the level of navigational safety, and compliance with maritime regulations.
| Aspek | AIS Receiver | AIS Transponder (Class A / Class B) |
| Main functions | Receives data from other vessels only | Receiving and sending vessel data |
| Vessel visibility | Invisible to other ships | Visible to other ships and ground-based surveillance systems |
| Communication | One-way (incoming only) | Two-way (sending and receiving) |
| Data sent | None | MMSI, GPS position, speed, heading, navigation status |
| Navigation safety | Basically, just for monitoring | Tall, supports collision prevention |
| GPS Requirements | Not required | You must select a gear |
| Biaya | Lower | Higher |
| Regulations | Not required for large ships | Mandatory for certain vessels (especially commercial ones) |
Components Required for Setting Up an AIS Receiver
The AIS receiver setup consists of three main components that operate sequentially, from signal reception to the display of vessel data.
VHF antenna
It is designed to receive AIS signals on the 156–162 MHz frequency band. The quality of the antenna and its mounting position (the higher, the better) significantly affect the range. The coaxial cable is also important because signal loss can cause data instability.
Data Interface
Connecting the receiver to other devices:
- USB: for PCs/laptops (the simplest option)
- NMEA 0183: the legacy standard for navigation devices
- NMEA 2000: a modern network for marine devices
- Wi-Fi: for smartphones or cloud monitoring
Software / Display
Visualizing AIS data:
- OpenCPN for PC
- MFD on board (radar and GPS integration)
- Mobile app or cloud platform for real-time monitoring
Conclusion
An AIS receiver is a critical component of a vessel monitoring system that captures AIS signals from nearby vessels and converts them into navigational data that can be displayed in real time. With the support of a VHF antenna, data interface, and visualization software, an AIS receiver enhances situational awareness, maritime safety, and the efficiency of maritime traffic monitoring, particularly in port areas and congested waters.
However, for broader and more integrated operational needs, an AIS receiver alone is no longer sufficient. A system is needed that can process data in real time, is centralized, and can be integrated with various other maritime data sources.
To improve overall port visibility and operational control, use the Port Surveillance System from TransTRACK. This solution leverages AIS receiver technology as one of its primary data sources to provide real-time, accurate, and integrated vessel monitoring on a single platform.
With this system, port operators can:
- Monitoring ship movements in real time in the port area and its surroundings
- Integrating AIS data with other operational systems
- Improving safety and preventing collisions or vessel congestion
- Supporting real-time data-driven decision-making
Transform port oversight into a smarter, more centralized, and more efficient process with solutions from TransTRACK.
FAQ
Do I need a license to use an AIS receiver?
No. Because an AIS receiver is passive (it only receives signals), users generally do not need a special radio station license. This is different from an AIS transponder, which transmits signals and is usually subject to specific regulations.
What is the average range of an AIS receiver?
The range of an AIS receiver depends heavily on the height of the VHF antenna and environmental conditions, but generally ranges from 15 to 25 nautical miles (approximately 27–46 km).
Does the AIS receiver require an internet connection?
No. The AIS receiver operates directly using VHF radio signals without an internet connection. However, if the data is displayed via a cloud platform or web-based application, an internet connection is required for additional visualization.
Can I convert an AIS receiver into a transponder?
No, that’s not possible. The AIS receiver does not have a transmitter module, so it cannot be converted into a transponder. To transmit vessel data, a separate AIS transponder is required.
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