The SLS 4120 is a system for the calculation and visualisation of longitudinal and transversal speed over ground, distance travelled relative to the ground and consists of four components: the Electronic Unit, the Display Unit, the DGPS sensor and the DGPS antenna.
The Display Unit is optimised for the intended purpose and consists of several numerical and alphanumerical LED segment displays. 6 keys are available for user input as well as a buzzer for audible warnings. The communication between Display Unit and Electronic Unit is established via a serial interface compliant with IEC 611612-1. Normally optimised for console mounting, the Display Unit is sized to the international 144 mm x 144 mm standard. Furthermore a ruggedised housing is available. Display Unit power supply is 24 V DC.
The Electronic Unit offers 8 serial interfaces (compliant with IEC 61162-1 and 61162-2) providing information from the DGPS sensor and Gyro Compass as well as a Speed Through Water log to send the calculated speed information to the Display Unit. 4 digital relays and 1 digital input to handle different alarm types are available. Additionally the Electronic Unit is equipped with an Ethernet interface for configuration purposes. The Electronic Unit is supplied with power via its 24 V DC input which also distributes power to the connected components.
DGPS Sensor and Antenna
A common reception of satellite and differential signals are achieved via an all- weather DGPS antenna attached to the DGPS sensor via a single antenna cable using TNC connectors. The DGPS sensor is a high-precision GPS receiver with a dual channel beacon receiver for reception of IALA beacon DGPS corrections. The unit performs continuous RAIM calculations, thus enhancing the integrity of position data and attaches to the Electronic Unit for calculating the speed information.