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RE: Recording Question

To: Anna Hall <>,
Subject: RE: Recording Question
From: "Cornell III, Howard M" <>
Date: Tue, 29 Aug 2006 12:50:47 -0500

I looked up the USB Oscilloscope specs.  The Oscilloscope function takes
a million 12-bit samples per second, and the datalogger takes 100,000
samples per second.  As the bandwidth of your microphone is 50 kHz, the
100 kHz sample rate is adequate.  Although the USB 2.0 has a high data
rate, there is some unpredictable bus overhead that may interfere with
using the bus continuously.   Yet many audio devices, with several
tracks of 96 kHz data, have solved this problem.  Will this bother you?
Perhaps you can place a waveform generator at 50 kHz as an input and see
how much of the data survives.  Also see if your datalogging software
has a large enough sample storage buffer to overcome times that Windows
takes over the computer (a few milliseconds every second): that could be
part of the same test, I guess.  

I have sent an email to USB Instruments to see if their datalogging has
an antialiasing filter; but they are in Europe and may not have been up
waiting for my inquiry.  You will need to prevent aliasing, as any data
component with a frequency so high that it does not allow two samples
per sampling period will show up at a lower frequency; but you probably
knew that.

Howard Cornell

-----Original Message-----
 Behalf Of Anna Hall
Sent: 25 August 2006 16:54
Subject: recording question

Hello all,

I am recording harbour and Dall's porpoise echolocation clicks to my
computer using a Cetacean Research Technology C54XRS hydrophone
connected through a DS1M12 USB Instruments Oscilloscope.

I had trouble with my Toshiba Satellite which dropped 2.4% of data at a
2us sampling rate.

Has anyone had experience recording acoustic data using a Toshiba Tecra
A7 unit?

The Tecra spec's are 2.0 GHz Intel Core Duo processor, 100 GB hard
512 MB RAM, but can be expanded to 4 GB.

Thanks for any advice.

Anna Hall, PhD candidate
Marine Mammal Research Unit
University of British Columbia

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