SAS Solar Tracker

SAS Solar Tracker

The SAS Solar Tracker works in conjunction with the Surface Acquisition System (SAS) (measures above-water ocean colour) to maintain the correct pointing angle with respect to the sun, and thus permits autonomous operation.

The SAS Solar Tracker works in conjunction with the Surface  Acquisition  System  (SAS) (measures above-water ocean colour) to maintain  the  correct pointing  angle  with respect to the sun, and thus permits autonomous operation.

Bigelow Laboratory for Ocean Sciences® researchers Dr. Barney Balch, Bruce Bowler and David Drapeau developed the Underway Aiming System (UAS™) software to address the challenge in ocean colour measurement of aiming shipboard optical sensors at optimal viewing angles from the sun. The UAS™ solution uses the real-time date, time, ship’s position and course to determine the angle of the sun from the sensors, and to position the sensors at the optimal azimuth angle.  The UAS™ performs this calculation in real-time in response to the constantly changing relative positions of the sun and sensors so that optical measurements may be made autonomously with improved accuracy.

Satlantic collaborated with the Bigelow Laboratory for Ocean Sciences® to bring the UAS™ technology to the ocean research community in the Satlantic Surface Acquisition System (SAS) Solar Tracker.  The SAS Solar Tracker consists of a radiometer instrument frame, rotator, and controller with data logging, GPS, electronic tilt and compass sensor, and ship navigation data feed.  The SAS Solar Tracker hosts Satlantic ocean colour radiometers, and optional pyrometer for measuring sea surface temperature mounted on the instrument frame and connected to the controller.

The SAS Solar Tracker autonomously performs measurements when the elevation of the sun and the orientation of the ship allow, subject to operator settings. For example, the SAS Solar Tracker would not collect data at night, or in daylight when the sun is too low in the sky, or when due to ship’s course, the ship’s structure would block the required view of the water. With data storage for months of operation, the SAS Solar Tracker’s autonomy frees busy science crew for other tasks and makes it suitable for deployment on volunteer observing ships.


  • Drive Unit to adjust the viewing angle of the frame
  • Frame for mounting the sensors
  • Precision Lt, Li and Es measurements
  • Adjustable viewing angles from Nadir and Zenith
  • Orientation (azimuth, pitch, roll) measurements
  • Sea-surface temperature
  • GPS for geo-referencing and time tagging
  • Flexible configuration
  • Internal data logging
  • Low power consumption
  • Compact system design
  • Easy to deploy

Garmin GPS 19x HVS GPS Receiver

  • Embedded receiver and an antenna
  • Precise navigation updates once per second
  • Can access Wide Area Augmentation System (WAAS) and differential GPS services
  • Withstand immersion in 1 m of water for 30 minutes

Miniature Deck Unit (MDU)

  • Serves as both a nominal 48 VDC power source for the Junction Box and as a RS-422 to RS-232 level converter
  • Connects to DC power supply, data logging computer and the Junction Box

Junction Box

  • Converts 48 VDC supplied by the MDU over the power/telemetry cable to 12 and 24 VDC for sensor ports
  • Converts sensor serial data communication from RS-232 to RS-422 for transmission over the power/telemetry cable to the MDU
  • Voltage conversion and serial data communication signal conversion enables duplex communication between the SAS and the data logging computer over a long distance
  • Receives data from sensors and optionally ship navigation
  • Controls the drive unit
  • Streams output via the MDU to a logging computer
  • Logs data internally to USB mass storage device.

SAS Mounting Frame

  • White coated metal, providing a rugged structure for instrument mounting
  • Mounting brackets for the sky radiance, water-leaving radiance, irradiance and pyrometer
  • GPS screwed on the top
  • Junction box is attached to the back
  • Mounted on top of the SAS Solar Tracker Drive Unit
  • Adjustable brackets for the sky radiance and water-leaving radiance sensors for viewing angle between 30 and 50 degrees from zenith or nadir

SAS Solar Tracker Drive Unit

  • Forms the base of the SAS Solar Tracker
  • Rotates the SAS Mounting Frame that is mounted on top for optimal measurement direction
  • Receives power and transmits telemetry via its 6-pin port
  • Receives ship navigation data via its 8-pin port
Product Data Sheet

SAS Solar Tracker Datasheet

Wednesday, August 3, 2016
PDF icon datasheet_SASsolarTracker.pdf
Product Manual

ProSoft 7.7 Manual

Satlantic ProSoft 7.7 Manual.

Thursday, April 14, 2016
PDF icon ProSoft-7.7-Manual.pdf
Product Manual

SAS Solar Tracker Manual

Wednesday, April 20, 2016
PDF icon SAS operation manual.pdf