USGS Open-File Report 02-045, ORGN00005 Chirp Subbottom Data Archive--Disc 1, Equipment

Open-File Report 02-045, Chirp Subbottom Data, Northeastern Gulf of Mexico, Disc 1

Title Page - Introduction - Cruise Report - Equipment - Chirp Data - Shotpoint Maps - Navigation - Pictures - Metadata

Equipment

Data Acquisition Equipment

Sidescan-Sonar and
Chirp Subbottom Towfish:

Datasonics model SIS-1000

Data Collection Platform:

Triton Elics International ISIS^TM

Specifications for the Subbottom profiler portion of the SIS-1000:
(for more information, see Benthos, Inc. (http://www.benthos.com)

Transducer: Transmit projector array; line array receiving hydrophone; 30º conical radiation pattern
Frequency: 2kHz to 7kHz swept FM (4 KW output), synchronous with sidescan
Resolution: 10 cm
Processing: Calibrated transmit waveform stored in ROM, matched filter FFT digital 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: 170 lbs

Specifications for the ISIS^TM Acquisition System:
(for more information, see Triton Elics International http://www.tritonelics.com)

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^TM> system, which runs under the Windows 95 operating system and is built by Triton Elics International, Inc. (http://www.tritonelics.com), Watsonville, CA using a 12-bit (72 db effective dynamic range) A/D converter in conjunction with an array processor. ISIS^TM 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.