USGS
Equipment
Data Acquistion Equipment

Sidescan-Sonar and
Chirp Subbottom Towfish:




Datasonics model SIS-1000 (100 kHz)
Data Collection Platform:



Triton Elics International ISIS®

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
Specifications for the ISIS Acquisition System:
(for more information, see Triton Elics International)

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.