DESCRIPTION

EdgeTech’s 4100 Side Scan Sonar System is the long lasting workhorse of hydrographic surveying. The topside processor is either a 19-inch rack mountable case (4100) or a water resistant portable system (4100-P). EdgeTech’s DISCOVER Side Scan Sonar software runs on the 4100 and 4100-P.

The Model 272 towfish is a hydro dynamically stable, towed body that contains the electronics and transducers necessary to generate and receive side scan sonar signals. It is designed for use at depths up to 1000 meters. Various tow cable systems provide the mechanical means for towing the fish near the seafloor and the electrical means for powering the fish, triggering the transmitters, and sending the return signal to the topside for processing and display.

The Model 272-T towfish incorporates circuits for transmitting and receiving the 100 kHz side scan sonar frequency. The Model 272-TD towfish operates at either 100 kHz or the higher resolution 500 kHz selectable in the DISCOVER software.

Both the Model 272-T and 272-TD towfish feature the patented Saf-T-Link® shear pin feature. When cable tension on the towfish exceeds 180 Kg (400 lbs.) due to snagging on the seafloor or mooring lines, the nylon pin shears and the electrical connector between the cable and tow fish separates. The towfish then "flips" 360 degrees, transferring the tow point to the nose of the towfish and allowing it to be pulled clear of the obstruction. Normal operation is easily restored by remounting the towing arm with a new shear pin and refastening the connector. If only the tail fins snag, they will fall away and be loosely held by a nylon cord. The cord is designed to break if the snag persists to avoid loss of the towfish.

Both the 272-T and 272-TD features a patented Time Varied Gain (TVG) circuit that compensates for the known signal losses versus range. This not only facilitates processing, but also reduces the dynamic range requirements of the tow cable, thus reducing the susceptibility to electrical nose pickup.

The Model 272-T and 272-TD can both be towed with lightweight Kevlar tow cable or, for deeper waters, by double armored steel-cables.