|Acoustic Ground Discrimination System: a system that uses data from an echosounder to determine the type of the seabed
|A common computer format for human-readable text data
|The angular orientation of the system
|Autonomous Underwater Vehicle
|Bathyswath-2 Standard,also known as B2 Deck Unit
|High-frequency Bathyswath variant, working at 468kHz
|Low-frequency Bathyswath variant, working at 117kHz
|Medium-frequency Bathyswath variant, working at 234kHz
|A Bathyswath system with the electronics, motion sensor and sound velocity sensor installed in an underwater bottle.
|A sonar system that generates discrete beams of angular measurement to the seabed. Synonymous with ‘multibeam’.
|Computer-aided design: computer software drawing packages
|A nationally or internationally agreed baseline for height measurement
|Commercial-off-the-shelf: i.e., bought from a shop, rather than specially built for a one-off job
|Differential GPS: improves the accuracy of basic GPS by comparing the position obtained by a GPS system with that obtained at a fixed GPS station at a known location
|Digital Terrain Model: a digital ‘map’ of the seabed, where depth and sidescan data are stored with reference to their geographical position
|Digital versatile disk
|Electromagnetic compatibility: robustness to external electrical ‘noise’ signals, and limiting transmission of such unwanted signals
|A commonly used method for connecting computers together in local networks
|Field-Programmable Gate Array
|Greenwich Mean Time; time zone; the Bathyswath software works in GMT
|Global Navigation Satellite System
|Global Positioning System: a GNSS, maintained by the USA
|The angle that a sound ‘beam’ makes with the seabed
|The file used by the Grid Processor application to store its data. Uses an ‘.sxg’ file extension.
|The maximum reach of the sonar, measured horizontally along the seabed; compare with ‘Slant range’
|Measurement of physical characteristics of waters; commonly used to refer to those measurements and descriptions of navigable waters necessary for safe navigation of vessels
|A sonar system that measures depths by comparing the phase of the signal received on a set of vertically separated transducer staves. Also called ‘Phase Differencing Bathymetric System’ (PDBS)
|A unit that provides mains (120 or 240V AC) power supply from a DC supply, usually from a battery
|Input – output
|The distance between survey lines run across the seabed
|Line Voltage Conditioner: a unit that ‘cleans’ a power supply, to reduce the effects of ‘noise’ or possibly damaging ‘spikes’ in the supply
|Motion Reference Unit
|A standard computer interface for marine equipment, maintained by the US National Marine Electronics Association
|Network Time Protocol: a method for synchronising computer clocks over a network
|Original Equipment Manufacturer
|The electronic user manual that is accessed directly from Swath Processor
|A method used to calibrate the relative locations and angles of the components of a survey system, by comparing depth results from overlapping survey runs
|Recording the time of a data sample using the time of the computer’s clock at the instant the sample is received in the software. Compare with ‘Sensor Clock’
|Phase Differencing Bathymetric System; see ‘Interferometer’
|A complete transmit-receive cycle, measuring depth and sidescan information over a profile of the seabed. Also sometimes used to refer to just the transmitted acoustic signal.
|Processing sonar data after it has been collected; compare with ‘real time’
|A system of electronic pulses for synchronising subsystem clocks
|Pulse (or Ping) Repetition Frequency
|A 2D set of depth measurements, usually taken sideways from a survey vessel
|Power Supply Unit
|Raw data file
|The file used by the Swath Processor application to store raw data. Uses a ‘.sxr’ file extension.
|Data processing at the same time as data is collected; compare with ‘Post-processing’
|Rigid inflatable boat
|Remotely-operated underwater vehicle
|A commonly used format for serial data connections
|Real-time kinematic GPS: an accurate form of GPS measurement
|Recording the time of a data sample using a clock maintained inside the sensor itself. Compare with ‘PC Clock’
|The file used by the Swath Processor application to store its settings. Uses a ‘.sxs’ file extension.
|Images of the seabed using the amplitude (strength) of the acoustic returns from the seabed. These are usually represented as grey pixels in a ‘waterfall’ display on the screen, with the brightness of pixels representing the strength of the signal.
|The maximum reach of the sonar, measured in a direct line from the sonar transducers to the seabed; compare with ‘Horizontal range’
|Reduction of the amplitude of the sonar signal as it passes through the water
|Change in height of a vessel in the water as the vessel moves
|An area of the seabed is usually surveyed by running a series of parallel straight lines across it
|The Swath Processor application
|A ‘ribbon’ of seabed depth measurements, made up of a series of ‘profile’ measurements of depth as the sonar is moved forwards over the seabed
|Previous versions of the Bathyswath sonar were called “SWATHplus”
|A real-time data acquisition and control program for Bathyswath, which can be compiled to run on Linux, Windows, and other operating systems
|Measuring the depth in a line extending outwards from the sonar transducer, then moving forwards to build up swaths
|A data format used to transfer data over Ethernet. UDP/IP (UDP) is another type. TCP/IP is a more reliable protocol, but is slightly slower.
|Transducer Electronics Module
|Software that is produced by organisations other than Bathyswath or its clients
|Transducer Interface Unit: the box containing the TEMs
|The component that is placed in the water and converts sound energy into electrical signals and vice versa
|Time-varying gain: an adaptable gain correction applied to sidescan data to remove the gross changes in amplitude caused by range and transducer beam shape, leaving an image of the seabed itself
|User Datagram Protocol; see ‘TCP/IP’
|Uninterruptible Power Supply: a power supply that maintains a mains power supply from battery if the mains supply (e.g. from a generator) fails
|Universal Serial Bus. A common computer peripheral interface.
|Unmanned Surface Vehicle (radio-controlled or autonomous boat)
|Coordinated Universal Time; a time zone, equivalent to GMT
|Universal Transverse Mercator: a commonly used format for representing latitude and longitude positions in a plane representation as Easting and Northing
|Unmanned Underwater Vehicle: includes AUVs and ROVs
|The V-shaped mechanical assembly that holds a pair of transducers
|An industry-standard data format commonly used for sidescan data. These files use a ‘.xtf’ file extension.
|A position in three-dimensional space
|Three-dimensional position plus amplitude
|An NMEA 0813 protocol message that is used with PPS signals to synchronise subsystem clocks