DESCRIPTION

The 2000 Series is a combined side scan sonar and sub-bottom profiler that is deployed in a towed vehicle or is installable on a ROV.

Side Scan Sonar
EdgeTech’s Shallow Water Full Spectrum CHIRP side scan sonar is a calibrated wide band digital FM sonar that provides quantitative and qualitative, high resolution, low-noise side scan imagery. It transmits linearly swept FM pulses centered at either 100/400 kHz or 300/600 kHz frequencies. The transmission of a longer duration, wide bandwidth pulse results in higher resolution sonar images and, because more energy is projected into the water, greater SNR resulting in extended range.

Sub-Bottom Profiler
The Full Spectrum CHIRP sub-bottom profiler has a number of advantages over conventional sonars. This includes increased penetration and higher resolution. The tapered waveform spectrum, results in images that have virtually constant resolution with depth. Another advantage is the reduction of side lobes in the effective transducer aperture. The wide bandwidth of the sweep frequency has an effect of smearing the side lobes of the transducer. The result is a beam pattern with almost no side lobes. This allows the towfish to be towed very close to the bottom, minimizing destructive signal scattering caused by the sediment.

TOWED
Two (2) towed versions of the system are available. The difference is in the sub-bottom profiler frequency range and the depth ratings of the towfish. The 2000-CSS System has a 500 Hz-12 kHz sub-bottom profiler and is rated to a max depth of 300m while the 2000-DSS System has a 2-16 kHz sub-bottom profiler and is rated to a max depth of 2,000m.

The towfish contains a dual frequency side scan sonar, the sub-bottom profiler transmitter and receivers, and all of the Full Spectrum CHIRP electronics required to generate and then transmit and receive and process the sonar signals. Sonar and other data are transmitted to the surface via a

digital link where a PC based data acquisition, storage, and printing processor running DISCOVER side scan sonar and sub-bottom profiler software is the user interface to the underwater portion of the system.

ROV
A version of this combined side scan sonar & sub-bottom profiler is available that is specifically designed for small, limited payload AUVs. It can also be installed on a small ROV with limited payload capacity.

A system consists of a payload module that contains the sonar electronics, a built in sub-bottom profiler transmitter and side scan sonar arrays with integrated sub-bottom profiler hydrophones. A large capacity hard drive installed in the system electronics is used to store sonar data.

The average data flow is dependent on the sampling frequency, on the data window size, on the ping rate of the sub-bottom profiler, and on the range scale setting of the side scan sonar.

Careful attention has been paid to keeping the power consumption low for the system. The amplifiers are turned off between transmissions. The amplifier power output can be controlled and the ping rate can be adjusted via the payload control interface.

On the surface, an EdgeTech Model 2000 Topside Display Processor with DISCOVER software displays and stores the sonar data.

The system is available as a combined dual frequency side scan sonar and sub-bottom profiler. Integration between the two sonars permits them to be triggered in such a way as to eliminate or minimize acoustic interference between the two.

The system can also be ordered as a side scan sonar or sub-bottom profiler only. It can be upgraded later by adding an electronics kit and sonar arrays.