Marport, a leading subsea acoustics technology company, has announced availability of its second generation digital net sounder.
On 1 February 2006, Marport announced it would be undertaking a major R&D effort in broadband acoustics technology for sounders and sonars. This effort has resulted in a complete series of ground-breaking underwater acoustic products that Marport will introduce during 2007. The first of these new products is Trawl Explorer G2.
Trawl Explorer G2
Trawl Explorer G2 is the world’s first software-defined, broadband net sounder. It integrates advanced broadband transducer technology, high speed acoustic communications, innovative image and signal processing software and the latest deep sea battery technology into a powerful yet cost effective wireless net sounder. The sounder combines new advances in subsea acoustics technology with a radical new physical design to provide maximum flexibility for mid-water and bottom trawling operations.
The system’s software-based architecture ensures that its performance will increase as improvements in image and signal processing technologies evolve. This allows for fast, convenient upgrades to keep owners and operators at the forefront in fishing technology as well as protecting their equipment investments. Product upgrades will be distributed via email or can be downloaded via the internet, another industry first. This enables customers to quickly gain access to new developments and state-of-the-art acoustics technology.
Trawl Explorer G2 is the first net sounder to use broadband transducer technology. By updating its transducers with broadband transducers, Trawl Explorer G2 can achieve significant gains in bandwidth and sensitivity. Broadband transducers transfer energy with greater precision and efficiency, while increased transducer bandwidth and sensitivity offers significant performance advantages, particularly in imaging resolution. The ability to sense, process and display more information results in echosounder images of remarkable clarity and detail. Trawl Explorer G2 heralds a new generation in underwater sensing, communications and image quality.
The new transducers increase bandwidth with a minimal effect on acoustic sensitivity, resulting in faster acoustic pulse rise and fall times. Fast pulses produce precise target echoes that allow detection and display of fish that are located very close to the seafloor as well as those fish that are near the head-rope. The transmitted pulses and resulting echograms are extremely crisp and detailed enabling maximum fish detection and bottom discrimination.
With broadband transducers, Trawl Explorer G2 becomes ‘tunable’ which allows the operator to ‘tune’ the best sounding frequency from a continuous spectrum, taking full advantage of the transducer’s bandwidth. The underwater sounder will operate with dual downward and/or upward frequencies for enhanced fish detection and imaging. The low band will range from 40 to 60kHz, while the high band will range from 120 to 190kHz. The operator will be able to tune the sounder to the best frequency based on the target species or the environmental conditions. Higher sounder frequencies provide narrow beams and allow for the detection and display of smaller fish. Lower frequencies provide better imaging in fast changing water depth (steep slopes, canyons, etc.). Lower frequencies also generate wider beams and have better deep water performance.
The wireless telemetry uplink frequency will range from 30 to 50kHz. This capability will significantly reduce acoustic interference from nearby vessels and enhance wireless telemetry communications between the head-rope mounted net sounder and the vessel.
By spanning broad frequency ranges, Trawl Explorer G2’s new broadband transducers demonstrate the concept of a ‘one-transducer’ solution. This means that only one transducer can be used for a wider range of commercial fishing operations, thereby offering enhanced performance and image quality. Additionally, it opens the door for new applications currently not available using conventional transducers – such as detailed classification of seafloor characteristics, precise trawl positioning, and very accurate species and biomass measurements. In the near future, Marport sounders can be upgraded to support an advanced signal modulation protocol often referred to as ‘chirp FM’. The chirp frequency modulation will improve discrimination between closely spaced fish targets, enhance signal-to-noise ratios and increase the sounder’s battery life by reducing overall power consumption.
Advanced digital signal processing
The underwater wireless sounder is deep sea rated for operating depths to 2,000 metres and a wireless transmission range of 4,000 metres. The sounder uses a unique new rechargeable battery technology that provides battery life of up to 100 hours on a single charge as compared to others in the industry that only last 16 hours. The sounder’s body is constructed from molded polyurethane with an inner sub-frame of marine grade aluminum. Like all Marport sensors, it’s designed for the toughest ocean conditions.
The sounder uses advanced onboard digital signalling processing software to minimise the effects of underwater noise and interference. The processed data is transmitted via a wireless acoustic link to the ship’s hydrophone. The hydrophone is networked to a multi-band acoustic receiver for signal demodulation. The receiver transfers the data to a bridge processing computer using Ethernet networking. On the computer, Marport’s CommandView software serves as an interface to the system and presents 2D and 3D visualisations of the trawl’s behaviour.
CommandView software display provides the operator with crucial information about what is happening in and around the trawl. Due to the net sounder’s position on the head-rope, highly accurate measurements can be made. It displays trawl opening height, depth to the bottom, water temperature and the presence of fish over, under and in the trawl. Many operators use the sounder to monitor bottom contact parameters. The system supports six display modes: Down Only, Up Only, Simultaneous Up/Down, Double Down (dual frequency), True Motion and History.
Pre-production units of Trawl Explorer G2 will be available this month.
Marport is now booking orders for production units to be delivered by mid-April 2007.
