UDDAS Specifications

Broadband recording unit:

The heart of the recording unit is a single-board computer by Aaeon electronics (model: GENE 4310) with a low-power 233 MHz processor. It conforms to a PC-104 format. Stacked onto the computer are a PCMCIA module, a hard drive module and a power supply module, all connected via the PC-104 bus. The PCMCIA module holds an A/D board by Measurement Computing (model: DAS16/330) capable of sampling up to 330 kHz. The hard drive module carries a 6 GB 2.5" Toshiba hard drive. The computer operates on Windows 98 and the data acquisition software is written in LabView. The acquisition program waits for a user "TTL-high" trigger to begin recording. Typically, data is acquired at a sampling rate of 220 kHz (110 kHz Nyquist) in 10-second blocks.

A custom-built directional transducer made of a piezocomposite material receives incoming signals. It has a flat sensitivity of approximately -180 dB re 1 uPa up to at least 150 kHz. A signal-conditioning unit in the housing is mounted below the computer stack to amplify and filter incoming sounds before recording. Signals are amplified by 40 dB with a user option to amplify an additional 10 dB. A 5th order low-pass filter by Lattice Semiconductors (model: ISPpac-80) is used as an anti-aliasing filter. It is programmed to have a cutoff frequency of 100 kHz.

Video camera unit:

A Sony digital video camera (model: DCR-PC110) is used to record simultaneous behavioral data. The camera is housed in a customized housing manufactured by Ocean Images. A trigger switch near the left handle connects via a cable to the electronics housing mounted below the camera housing. An omnidirectional hydrophone (built by Don Norris) with a sensitivity of - 205 dB provides acoustic input for the video camera. Inside the camera housing, a custom-built pre-amp provides 20 dB of gain before the signal is fed into the camera.