GPS transponders

The Seatrack 220/320 represents a new generation GPS transponder used in 3D and vertical seismic surveys for streamer tailbuoy/gunfloat positioning, as well as marine operations such as like barge management, and vessel traffic monitoring. It includes a 12-channel, high-performance GPS receiver, a synthesized UHF radio, antennas and a communication computer packaged in a robust, self-contained unit.

GPS data is collected and transmitted to the vessel by the internal UHF radio or a communication line. Time Division Multiple Access (TDMA) is used for multiple unit transmission at a common frequency.

Seatrack 220 is developed for tailbuoy operation while the even more robust Seatrack 320 is design to resist the extreme shocks at a gunfloat.

The Seatrack 330 represents a new robust extension to the Seatrack product line. A built-in damping mechanism is developed to reduce shock exposure to the electronics including the GPS antenna. The design is verified by running a single unit through more than 1.000.000 extreme shock cycles without failure.

The environment on a seismic source is extremely challenging for all types of electronics. Firing the air guns may cause high-energy shocks of more than 50G with 10 ms duration. Repeated every few seconds, day and night, for periods of several months gives new meaning to the term shock exposure. Seatrack 330 is designed to withstand this harsh environment.

The Seadiff RNAV is a software package used to collect and process relative GPS positioning data from the Seatrack 220 and VCU 200. As many as 24 Seatrack units may be interfaced simultaneously. Quality control of GPS observations is implemented according to UKOOA recommendations. RTK capability for centimeter-level accuracy is possible.

The user interface allows easy control of all relevant parameters and provides an overview of system performance in real time and as time series plots. Data logging for post processing is achieved by running Seadiff RNAV in the replay mode. For absolute accuracy, the Seadiff RNAV accommodates one or more links for differential corrections.

Marine traffic control and vessel management are the target applications for the Seatrack VTS (Vessel Tracking System). This small, shock resistant, waterproof GPS transponder package is designed for two-way communication with an operations center and for ECS (Electronic Charting Systems) data input.

The Seatrack VTS contains either a standard or high-performance 12-channel GPS receiver. The on-board computer allows easy interface with communication methods such as a GSM telephone or a VHF radio. DGPS position accuracy may be achieved by adding an IALA, FM-RDS, UHF or and satellite services receiver to the system.

Fleet management and vehicle tracking on land are the typical applications for the Seatrack AVL (Automated Vehicle Location). The shock-resistant, small size package monitors location via GPS and relays positioning information to a driver's display and to radio systems for transmission to an operations center.

The Seatrack AVL contains a standard or high-performance 12-channel GPS receiver along with a computer for data processing and interfacing with a GSM cellular phone or a VHF radio. IALA, FM-RDS and UHF receivers may be included for DGPS correction signal accuracy enhancement.

Seatex has manufactured AIS systems (Automatic Identification System) for several years. The AIS transponder will send its GPS position to a central controlling unit or to other transponders. AIS - transponders use a Seatrack proprietary protocoll and standard radio communication techniques.

An international standard for AIS based on IMO recomandations is now beeing developed by the IEC. The new AIS system will be named Universal AIS - UAIS.

Detailed information: [Seatex AIS]