Irish Ports Implement Thales Systems

Acting ahead of an International Marine Organization (IMO) -mandated Automatic Identification System (AIS), the harbormasters of Cork and Shannon, Ireland, have implemented Thales Navigation tracking systems within their STN Atlas VTS installations. By equipping key harbor craft with Thales Navigation TDMA (Time Division Multiple Access) transponders, the ports have overcome the geographical limitations of radar and achieved a dramatic advance in the efficiency and safety of their operations. Thales Navigation transponders are similar to AIS, but the Thales Navigation system includes the major advantage of giving the port operator complete control over it. AIS transponders are required to function independently of any control center so that two ships meeting in mid-ocean can exchange and display information automatically. The ship's master decides the content of the display, and no port controller can change it or choose not to receive its messages. The Thales Navigation TDMA system operates within a designated area for which there is a central control. All transponder messages lead to the port controller who has options unavailable on the AIS system. With TDMA the port controllers have the freedom to control the reporting intervals and content of the transponder signals. They can also set up guard zones that can trigger alarms if a harbor vessel crosses a demarcation line, and they can remove a target from the display if crowding makes it desirable. For ports such as Shannon and Waterford, where the VTS radar sites are far apart; the TDMA transponder network can transmit the radar track table data back to the port control. This eliminates the need for costly tied telephone lines or microwave data links between each station and the control headquarters. Because this data is also transmitted to all other TDMA units in the region, the same complete VTS radar image can be seen by the Coast Guard, on pilot vessels or wherever a radar display is linked to a TDMA receiver. The transmission costs of the system are zero, so the system can also be used to distribute tide gauge and wind speed data around the network as an additional aid to pilots and harbor craft. The system automatically transmits precise differential GPS corrections to all vessels equipped with a TDMA unit operating within the area.