ZS2EZ SHIP TRACKING
participate in the MarineTraffic vessel tracking project. Situated only
a few km from Port Elizabeth Harbour (elevation 68m ASL), my station
consists of a Raspberry Pi-Based COMAR SLR350Ni receiver connected to a
162MHz endfed dipole mounted on my tower some 47ft above ground.
Data is fed directly to the MarineTraffic Internet Server via a
10Mbps Fibre Internet connection, where it is assimilated into their
To see my MarineTraffic Station Page (Port Elizabeth - Station#5292) click here
About the Marine Traffic project
This project is part of an academic, open, community-based project. It
is dedicated in collecting and presenting data which are exploited in
research areas, such as:
- Study of marine telecommunications in respect of efficiency and
- Simulation of vessel movements in order to contribute to the safety
of navigation and to cope with critical incidents
- Interactive information systems design
- Design of databases providing real-time information
- Statistical processing of ports traffic with applications in
- Design of models for the spotting of the origin of a pollution
- Design of efficient algorithms for sea path evaluation and for
determining the estimated time of ship arrivals
- Correlation of the collected information with weather data
- Cooperation with Institutes dedicated in the protection of the
It provides free real-time information to the public, about ship
movements and ports, mainly across the coast-lines of Europe and
N.America. The project is currently hosted by the Department of Product
and Systems Design Enginnering, University of the Aegean, Greece. The
initial data collection is based on the Automatic Identification System
Below is the map of tracked
How the vessels positions are recorded?
The system is based on AIS (Automatic Identification System).
As from December 2004, the International Maritime Organization (IMO)
requires all vessels over 299GT to carry an AIS transponder on board,
which transmits their position, speed and course, among some other
static information, such as vessel’s name, dimensions and voyage
What is AIS?
AIS is initially intended to help ships avoid collisions, as well as
assisting port authorities to better control sea traffic. AIS
transponders on board vessels include a GPS (Global Positioning System)
receiver, which collects position and movement details. It includes
also a VHF transmitter, which transmits periodically this information
on two VHF channels (frequencies 161.975 MHz and 162.025 MHz – old VHF
channels 87 & 88) and make this data available to the public
domain. Other vessels or base stations are able to receive this
information, process it using special software and display vessels
locations on a chart plotter or on a computer.
What is the range AIS covers?
Normally, vessels with an AIS receiver connected to an
external antenna placed on 15 meters above sea level, will receive AIS
information within a range of 15-20 nautical miles. Base stations at a
higher elevation, may extend the range up to 40-60 nm, even behind
remote mountains, depending on elevation, antenna type, obstacles
around antenna and weather conditions. The most important factor for
better reception is the elevation of the base station antenna. The
higher, the better. We have seen vessels 200 nm away, with a small
portable antenna placed on an island mountain on 700 meters altitude!
Our base stations cover fully a range of 40 miles and periodically
receive information from some more distant vessels.
How is the data collected?
Our base stations are equipped with an AIS receiver, a PC and
an Internet connection. The AIS unit receives data, which are processed
by simple software on the PC and then sent to a central database by
means of a ‘web service’. This software is free for anyone interested,
under a GNU license.
Data received by the AIS unit are encoded in NMEA sentences
(64-bit plain text). A sample is shown below:
Messages include the following three basic types:
1. Dynamic Information, such as vessel’s position, speed, current
status, course and rate of turn.
2. Static Information, such as vessel’ name, IMO number, MMSI number,
3. Voyage-specific Information, such as destination, ETA and draught.
How often is the data updated?
Data received are uploaded in the database in real time and therefore
they are immediately available on the map and on other pages. However,
several positions shown on map may be not continuously refreshed (e.g.
when a ship goes out of range). Vessel positions shown on map may be up
to 1 hour old. Please note also that map web page is only periodically
refreshed or whenever the ‘Refresh now’ link is pressed manually.
BACK TO ZS2EZ