Dear Anna,
I have had similar experiences with other USB devices and fear that it is
something fundamental in the USB bus - my problems get worse the busier the
PC is and the greater the number of other USB devices. I have experienced
this with a variety of sound cards and a variety of different computers. The
problem is not obvious at first, but when analysing an hour long recording,
I notice that the number of samples is between 0 and 5% less than expected.
I no longer use USB devices for audio input. Firewire sound cards seem OK,
but won't run at sufficient sample rate for harbour porpoise vocalisations.
For porpoise frequencies you could use a National Instruments data
acquisition board. NI boards may not work with the software you are
currently using, but we used them successfully on last years SCANS survey
for porpoises in European waters, acquiring data with the IFAW software
'RainbowClick' available at www.ifaw.org/sotw. To analyse porpoise clicks in
real time (rather than just acquire data) you would probably need a faster
machine than your Toshiba, but you'll have no trouble recording to hard
drive. The IFAW 'Logger' software will record from NI cards, as will Dave
Mellingers Ishmael (I think !), both of which are free. I'm sure there are
plenty of other packages out there too.
If anyone out knows of a PC sound card that will run at 500kHz and connect
to firewire, I'd love to know !
Douglas.
==========================
Douglas Gillespie
Sea Mammal Research Unit,
Gatty Marine Laboratory,
University of St. Andrews,
Fife, KY16 8LB
Scotland.
-----Original Message-----
From:
Behalf Of Anna Hall
Sent: 25 August 2006 16:54
To:
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 drive,
512 MB RAM, but can be expanded to 4 GB.
Thanks for any advice.
Sincerely,
Anna Hall, PhD candidate
Marine Mammal Research Unit
University of British Columbia
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