Specifications for the Chirp
subbottom profiler portion of the SIS-1000:
(for more information, see Benthos,
Inc.)
Transducer: Transmit projector array; line array receiving hydrophone;
30-degree conical rotation pattern
Frequency: 2kHz to 7kHz swept FM (4KW output), synchronous with
sidescan-sonar
Resolution: 10 cm
Processing: Calibrated transmit waveform stored in ROM, matched
filter FFT signal processing
Scale Selection: 25 meters to 750 meters full scale
Tow Vehicle Specifications:
Depth Rating: 1000 meters
Vehicle Dimensions: 18 inches OD x 64 inches long
Weight: in air: 300lbs; in water: 170lbs
|
 Windows 95
based Pentium machine
Saves sidescan-sonar
data via network interface or on an Exabyte 8200 tape subsystem
Will accept up
to 5 channels of data
Serial I/O ports
(i.e., for navigation)
Parallel (Centronics)
ports for printing the sidescan-sonar data
Array processor
handling the digitized sidescan-sonar signal
12 bit analog
to digital converter OR:
DSP card for digital
signals
The topside data acquisition computer the USGS uses to collect and store
the digital signal is the ISIS® system,
which runs under the Windows 95 operating system and is built by Triton
Elics International, Inc., Watsonville, CA using a 12-bit (72 db
effective dynamic range) A/D converter in conjunction with an array
processor. ISIS® is capable of digitizing
up to four channels of information at aggregate rates of up to 750 kHz,
thus preserving the content and the dynamic range of the sidescan-sonar
signal. An installed Digital Signal Processing (DSP) board is an alternative
to handling signals digitized at the towfish (SIS-1000). Port and starboard
sidescan-sonar data are displayed in real-time on a high-resolution
color display (1280 x 1024 pixels). Telemetry from navigation systems
and the towfish, including full towfish attitude information, is displayed
in separate windows. The backup data storage media used is 8 mm Exabyte
tape. The USGS WHFC is currently recording directly to disk on
separate computer systems using the Network File System (NFS) protocol
and archiving the data to DVD-ROM.
|
