Functional Description; Introduction; Towfish - Klein 3900 Series Operation And Maintenance Manual

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1.4

Functional Description

This section provides a detailed functional description of the Series 3900 Sonar

System operation.

1.4.1

The Series 3900 Sonar System is a single beam side-looking sonar intended for

high resolution survey use. It departs from previous single beam systems in that

the swath forming process is implemented digitally using digital signal processing

(DSP), rather than analog delay lines, phase shifters, or multipliers and adders. The

primary advantage of this technique is a reduction in the size and weight of the

towfish and therefore a reduction in the size of the required survey vessel and

ancillary equipment, such as a winch and crane. Other advantages include more

flexibility in the swath processing, allowing software control of operating

parameters. Previously this would have required hardware changes.

The Series 3900 architecture is composed of the towfish, the tow cable, the laptop

computer, and the SP-II TPU. The towfish contains the transducer arrays and

electronic subsystems for transmission, reception and data acquisition, and

telemetry. The towfish also includes standard and optional sensors for monitoring

towfish position and motion and acquiring water depth, towfish altitude and other

data. The tow cable is a coaxial cable that provides power transfer and duplex

communications between the towfish and the SP-II TPU. The laptop computer

runs SonarPro and enables operator control of the system and displays and records

the sonar data. The SP-II TPU processes the data from the towfish and outputs this

data over a local area network (LAN) to the laptop computer.

1.4.2

The towfish is composed of the towfish housing, which has external brackets for

cable attachment, the transducer arrays (one for each side), the nose cone, the tail

section, and a pressure housing containing optional sensors and electronics. In a

typical operation the towfish is towed behind the survey vessel by means of the

tow cable. The depth at which the towfish runs below the surface of the water is a

function of both the length of the deployed cable and the tow speed.

Functional Description

1-5

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