Wartsila SATLOG SLS 4120

Wartsila SATLOG SLS 4120
Wartsila SATLOG SLS 4120

The Speed Log System Wärtsilä SATLOG SLS 4120 measures Speed Over Ground (SOG), referenced to the ship’s axes, by using the input from a gyro compass. With a precision of greater than 0.2 knots or 2 % of speed. This accuracy is compliant with the IMO performance standard for Speed and Distance Measuring Devices (SDME) IEC 61023 and allows the Wärtsilä SATLOG SLS 4120 to be used as a speed log for ground stabilising applications or docking manoeuvres. Interfaces between the Display Unit, Electronic Unit and DGPS Sensor comply with IEC 61162.

Together with an EM-Log or other log sensor measuring the Speed Through Water (STW), the Wärtsilä SATLOG SLS 4120 becomes a central display for speed related information such as Speed Through Water and Speed Over Ground, as well as distances travelled.


  • Worldwide precise speed determination without differential signals.
  • High adaptive double-end ferry mode.
  • Supporting of docking manoeuvres by calculating also the rate of turn and transversal speed at stern by interfacing a gyro compass.
  • Measurement of Speed Over Ground in the longitudinal and transversal ship direction.


  • Standard speed accuracy of 0.2 knots.
  • Speed accuracy of 0.1 knots in differential mode.
  • Multitrack Differential Beacon Receiver.
  • Comfortable configuration, maintenance andupdate of the SLS 4120 via the integrated web interface using a web browser.
  • Ready for remote maintenance due to the Ethernet interface.
  • Integrated 24V DC power supply for external components.


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.

Display Unit

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.

Electronic Unit

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.

Technical data

DGPS performance
GPS receiver12 channel L1, C/A code with carrier phase smoothing
Update rate5 Hz
Position accuracyGPS: 5 m; DGPS: 1m (2d RMS) typical
Cold start1 min typical
DGPS beacon receiverDual receiver with automatic tuning
Frequency283.5 to 325.0 kHz
MSK Bit Rates50, 100 and 200 bps
Cold start< 1 min typical
Reacquisition< 2 seconds typical
Sensitivity2.5 μV/m for 6 dB SNR at 200 bps
Speed accuracy
GPS-only modeComplies with IMO Res. A.824 and IEC 61023 / 0,2 kn or 2 % whichever is greater
DGPS mode0,1 kn or 1% whichever is greater
Serial ports8 serial interfaces compliant with IEC 61162-1:
– 1 port to be used as Display interface
– 1 port to be used as DGPS sensor interface
– 1 port to be used as Gyro interface
– 1 port optionally to be used as STW-log interface
Power interface4 24V DC power supply (max. 1 A) interface for connected equipment
Digital I/Os4 alarm relays:
– 2 programmable speed alarm (for rudder system, stabilizers or other applications)
– 1 power failure alarm
– 1 system failure alarm
– 1 digital input
Ethernet1 Ethernet 100 Mbit (RJ45)
Supply voltage, dimensions and weight
Display Unit
Supply voltage24 V DC (supplied from Electronic Unit)
Dimensions144 mm x 144 mm x 53 mm
Weight590 g
Electronic Unit
Supply voltage24 V DC (+30% / -10%)
Dimensions406,5 mm x 165,43 mm x 42,25 mm
Weight1900 g
DGPS Sensor
Supply voltage24 V DC (supplied from Electronic Unit)
Dimensions135 mm x 130 mm x 40 mm
Weight490 g
DGPS Antenna
Dimensions130 mm x 130 mm x 80 mm
Weight450 g
IEC 60945 General requirements
IMO Resolution A.694
IEC 61162-1 Digital interfaces- Part 1
IEC 61162-2 Digital interfaces- Part 2
IMO Resolution MSC 96
IEC 61023 Marine speed and distance measuring equipment (SDME)
IMO Resolution A.824
IEC 62288
IMO Resolution MSC 191
Type approvals
Requirements according to Marine Equipment Directive (MED), USCG


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