Ship Navigation Equipment

Gyro Compass

The BROWN has a Sperry Mark 37 gyro compass. The gyro has a syncro to digital converter installed and the NEMA heading messages are available for scientific use. The data is recorded by the shipboard data acquisition system (SCS). The Mark 37 gyro relies on manual latitude and speed corrections.
 

GPS

Three primary - a Trimble Centurian P-code GPS, a Magnavox MX-200 GPS, and a Northstar 941x differential GPS. Data outputs from all three GPS receivers are available for scientific use and are continually recorded by SCS. A GPS networked time code receiver is presently time synching the shipboard data acquisition system and the computer dynamic positioning system. Software is available for time synching the networked PC-based scientific computers.
 

Navigation

Two navigation software packages -SPAWAR Integrated Charting Engine (ICE) and Kongsberg Simrad SPS. Both run simultaneously on the bridge and have the ability to receive GPS input from P-Code or DGPS. Traditional paper charts are used as well.
 

Radar

Two Sperry Rascar Touch Screen navigational radars on the bridge. One radar is an S-band (10 cm) 30 kW radar and the other is an X-band (3 cm) 25 kW radar. Both radars are used for collision avoidance and navigation.
 

Simrad Robertson Dynamic Positioning System

Simrad Robertson Multi-purpose pilot system (RMP) is capable of operating in one of three different modes. In Manual Mode, the vessel is controlled using the Z-Drive hand controls. In Autopilot Mode, the system controls the vessel's heading while speed is controled through the hand controls. This is the same as any standard autopilot system. Dynamic Positioning Mode gives automatic computer control of the vessel. The system can hold a desired GPS position, perform measured maneuvers, follow a track, or a combination of these. Various navigational inputs are provided to give position reference and active wind compensation.
 

Doppler Speed Log

A Raytheon model DSN-450 Doppler sonar provides an indication of ship's speed, distance traveled and, at continental shelf depths, an indication of water depth. At deep ocean depths the speed is referenced to the water mass under the ship, water depth is inoperable. The output is displayed at several locations throughout the ship and fed into the ships autopilot. The speed output is also recorded on SCS and is available for scientific use.
 

Position Heading and Attitude Sensor

A Seatex Seapath 200 is used by the ship to determine the vessels position, heading and attitude (heave, pitch and roll). The unit provides this solution by combining raw data from a MRU and two GPS carrier phase receivers. The unit is stand alone and requires no outside input from other sensors for accurate heading, roll, pitch and heave. For more accurate positioning of the ship, DGPS correctors are applied. Heading, determined from GPS phase measurements between the two GPS carrier phase receivers, velocity and position from GPS together with roll, pitch, heading (yaw) and acceleration measurements from the MRU, is input into a Kalman filter. The filter outputs position and velocity in three axes.
 

NAVTEX

Receiver for receiving and printing the international automated medium frequency (518 KHz) direct-printing service which provides navigational and meteorological warnings and forecasts, as well as urgent marine safety information to ships. Receiver is located on the bridge.
 

Weather

Weather broadcasts, facsimile pictures and charts are gathered during ship satellite connections to the internet. Weather forecasts and alerts are also received from Inmarsat C and the US Navy Meteorological Forecasting Centers. The ship's Seaspace Terascan system receives visual, infrared, and water vapor images from NOAA geo-stationary satellites GOES 8 and GOES 10 and NOAA polar orbiting satellites.