DIDSON™ PRODUCT OPTIONS

For detailed information on these options, please download a pdf document DIDSON Product Options.

Orientation Sensor Standard in Diver-Held and optional in Unibodies A Honeywell TruePoint Compass placed in the Diver-Held or Unibody housing provides roll, pitch, and yaw (compass) in degrees with a stated accuracy of 1° rms. DIDSON presents the data both as numbers printed on the display and as a graphic. The orientation numbers are recorded in the DIDSON Data File (ddf). The graphic and numbers will be shown on the display when the file is replayed. The heading of the sonar is marked by the direction shown at the top of the circle. When heading changes, the circle rotates. The white line marks the horizon. When the sonar tilts downward, the white line rises. When the sonar rolls counter-clockwise, the line rotates clockwise. • Click on the image at right to see a film of the compass. • Click here to see another.
Silt Exclusion Enclosure (Silt Box) Some river sites support a heavy flow of suspended sediment. The DIDSON lens enclosure is open to ambient water and in those conditions can slowly fill with silt. For those occasions one can use the Silt Exclusion Enclosure or Silt Box. The Silt Box encloses the DIDSON in a relatively silt-proof container that keeps silt out of the lens housing and provides uninterrupted imaging in sediment laden water. The Silt Box measures 8” by 9” by 13” and currently is designed for the Rear Facing Connector 300 m units used heavily by fisheries management and research groups. The box could be modified to support Forward Facing Connector 300 m units. • More pictures on the pdf document DIDSON Product Options
Large Lens Set Option A large lens set 29 cm (11.5 in.) wide by 49.5 cm (19.5 in.) long almost doubles the resolution over the standard or LR lens sets. The large lens set also has a smaller vertical beampattern (approximately 3°). The combined concentration of horizontal and vertical beamwidths increases the returned signal from a given target by 10 dB. The lens set fits on a standard or LR Unibody DIDSON. The field of view of the Large Lens Set is 15° compared to 29° for the standard lens set.
Concentrator Lens A concentrator lens is a plano-concave lens that fastens onto the front lens of a DIDSON as shown. Space between the two lenses allows water to fill the gap to make sure no air is trapped and thus attenuate the sound. The lens concentrates or reduces the vertical beamwidth from the default 14° to either 3° or 1° depending on which concentrator is used. • Much more information in the pdf document DIDSON Product Options
Spreader for Large and Standard Lenses The Spreader Lens is a plano-convex lens that fastens onto the front lens of a Large Lens Set (LLS) or a DIDSON Standard Lens Set (SLS) shown at right. • Security and Inspections: Spreader Lenses are useful for hull searches and other up-close uses. The 28° two-way vertical angle for the SLS spreader doubles the vertical coverage at any given range. The Spreader on the LLS almost triples the vertical coverage. It generates 14° two-way vertical width versus the 3.5° vertical width of the LLS with no spreader. • Fisheries: The Spreader on the LLS makes it easier to image fish at close ranges. Fisheries customers want more detail at short ranges to determine species identification. • Specs: Standard Lens Set Spreader vertical width: 28° two-way pattern. Large Lens Set Spreader vertical width: 14° two-way pattern.
Communication over Extended Distances The standard 100/10BaseT Ethernet link will work over cables up to 200 ft long. This distance can be extended by changing the protocol and transmitting over a twisted copper pair up to distances of 4000 ft (1200 m) or over fiber optics for kilometers of range. Examples of converters successfully used are a Patton Ethernet Extender (model 2158) and a Prizm 100/baseT to Fiber Optic Converter. Sound Metrics does not sell the Prizm but does sell the Patton Ethernet Extender.
Cable Length Options The standard scope of supplies when one purchases a DIDSON includes a 50-ft cable. The exception is the Split-Body system which comes with a 25-ft cable. Additional cable lengths are available: 100 ft, 150 ft, 200 ft, and 500 ft. Cable lengths up to and including 200 feet come in a coil. The 500-ft cable comes on a sturdy plastic reel (picture at right) made to allow one to unwind either or both ends of the cable from the reel. • 500-ft Cable Kit: The 500-ft cable requires Ethernet Extenders. The extenders convert the 100/10 Base T protocol to a protocol that works over cables that are longer than 200 ft. The 500-ft cable kit includes a pair of Ethernet Extenders with one of them in a waterproof housing depth rated to 500 ft (150 m). One end of the 500-ft cable connects to the topside box. The other end of the 500-ft cable connects to the remote Ethernet Extender in the waterproof housing. A 50-ft cable connects between the sonar housing and the remaining connector on the remote Ethernet Extender in the waterproof housing. The 500-ft cable kit includes the following: 500-ft cable, reel, Local Ethernet Extender, Remote Ethernet Extender (in waterproof housing), and a 3-ft Ethernet Cable. A new design of our cable has a smaller diameter and less weight. It also has shown capability of running 10BaseT Ethernet without the need for Ethernet Extenders over a 500-ft length. Ask us for details.
Simple Pole Mount Sometimes all one needs to deploy a DIDSON is a simple articulated mount on a extensible pole. The mount angle allows adjustable sonar roll and tilt relative to the pole. The pole length is also adjustable.
Remote Auxiliary Lens The Remote Lens Exchanger allows one to mount and dismount a concentrator or spreader lens from a 300m depth-rated DIDSON when the sonar is deployed. This gives the operator two choices of vertical beamwidth: 14-degrees or one of 1, 3, 8, or 28 degrees. The lens is exchanged by a software command saving the time to bring up the sonar and physically changing the lens by hand. The Remote Lens Exchanger requires its own motor actuator and needs the new rear endcap that supports one.
8 Gigabyte Internal Memory (Compact Flash Card) Some DIDSON applications require autonomous recording. In this case there is no cable connecting the sonar to a host computer for control, display, and data storage. The sonar requires only a power source. The user sets up the sonar with the desired settings (range, frequency, frame rate, etc.), then puts the sonar in autonomous record mode and turns off the sonar. The user places the sonar in the desired location and applies power. The sonar loads the stored settings and begins recording into its internal memory. The 8 GB internal memory allows four hours of recording at HF at 10 frames/s. • Two applications that use autonomous recording are: 1) placing DIDSON in the mouth of a trawl net to monitor animal behavior as they approach and enter the mouth of the net, and 2) monitoring fish traps on the sea bottom.