Edgetech 3200-XS, Руководство пользователя

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SECTION 1: Overview
3200-XS Sub-Bottom Profiling System User’s Manual Doc. No. 990-0000026-1000, Rev. 2.3
1.2.1 Separate Acoustic Projectors and Receivers
The 3200-XS Sub-Bottom Profiling System uses acoustic projectors and acoustic receivers
mounted in a towed vehicle to transmit and receive acoustic FM pulse signals. The
projectors are wide band piston type transducers, and the receivers are hydrophone arrays
composed of lead zirconate titanate (PZT) crystals. The transducers are mounted in the
forward section of the tow vehicle, and the hydrophone arrays, which are designed for
profiling at ship speeds up to seven knots, are mounted aft. The use of separate
transmitting transducers and receiving hydrophone arrays preserves linearity and allows
the simultaneous transmission and reception of the acoustic signals. The transducers and
hydrophone arrays are mounted beneath acoustic baffles which minimize direct path, tow
vehicle and surface reflections. A preamplifier in the tow vehicle amplifies and drives the
received signals through a tow cable to the surface.
1.2.2 High Repeatability
The FM pulses are generated by a digital-to-analog (D/A) converter with a wide dynamic
range and a transmitter with linear components. Therefore the energy, amplitude and
phase characteristics of the acoustic pulses can be precisely controlled. This precision
produces high repeatability and signal definition which is required for sediment
classification. The frequency range of operation is determined by the acoustic
characteristics of the transmitter transducers and receiving hydrophone arrays mounted on
the tow vehicle. Each tow vehicle can transmit acoustic pulses with different center
frequencies and bandwidths. The selection of this frequency is made by the operator while
profiling to achieve the best imagery, and the tow vehicle is selected based on the
sub-bottom conditions at the survey site and the type of sub-bottom features that need to
be imaged. EdgeTech technical support can provide assistance in selecting the best tow
vehicle for your application.
1.2.3 High Signal-to-Noise Ratio
Full Spectrum chirp technology does not use a conventional matched filter—the correlation
filter that is widely used to compress FM signals—to process wide band signals. Rather it
uses proprietary amplitude and phase weighting functions for the transmitted pulse and a
pulse compression filter that maximizes the SNR of the acoustic images over a wide band
of operating frequencies. These functions provide a significant SNR improvement in the
acoustic image over other pulse and chirp sonars with band limited components that are
limited in dynamic range.