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Description : Greater yellowlegs recorded at 0516 on Aug 10, 2004, Yellow=
Island, San Juan County WA=20
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________________________________________________________________________
________________________________________________________________________
>From Tue Mar 8 18:27:49 2005
Message: 13=20=20=20=20=20=20=20
Date: Fri, 13 Aug 2004 14:53:15 -0500
From: Rob Danielson <>
Subject: RE: [naturerecordists] freq response and aliasing of Edirol FA-101=
at 192 kHz
Last I looked, the max gain of the built in mic
preamp on the FA-101 is 50dB. This should be
suitable for louder sources but not ideal for
distant sources or location ambience. Is this
consistent with your findings Gianni? I assume
you can close mic rats, but bats? I'd think more
gain would be pretty useful. Rob D.
At 1:40 PM -0500 8/13/04, Tyler McGhee wrote:
>so is this unit decent for lower quality recordings (below 192, say
>44.1, 48, 96, etc)
>i am really thinking of purchasing one of these but if the frequency
>response isn't
>flat at those sample rates, i'll keep looking.
>
>thanks!
>
>Tyler McGhee
>
>
>-----Original Message-----
>From: Gianni Pavan
>Sent: Thursday, August 12, 2004 4:42 PM
>To: ;
>Subject: Re: [laptop-tapers] RE: freq response and aliasing of Edirol
>FA-101 at 192 kHz
>
>
>Hi all,
> recording at 192 kHz is very useful when studying animals emitting
>their
>communicative or echolocation signal at frequencies higher than those we
>
>can hear. Mice, rats, bats, insects do emit sounds up to 100 kHz, but
>some
>emits (ultra)sounds ranging up to 120 kHz. Many others emit audible
>sounds
>with harmonics extending to more than 20 kHz.
>To record those sounds it is required to sample at very high rates with
>industrial sound acquisition boards that are expensive, require specific
>
>drivers, and often have 12 or 14 bits only.
>By using a very good board with 192 kHz sampling you can spend a lot
>less,
>you can use standard windows software and you get at least 16 bits of
>resolution. The LynxTwo board allows to work reliably up to 90-92 kHz.
>This
>means you can record most (but not all) of the ultrasounds emitted by
>terrestrial and aerial mammals. With marine mammals you can get a
>significative portion of their echolocation sounds that may extend up to
>
>160 kHz.
>Then, if you want to hear those sounds you can simply playback the files
>at
>reduced rates, 48 kHz for example.
>
>I was hoping to find a portable device to setup a field recording,
>laptop
>based workstation able to capture sounds up to 90 kHz.
>Unfortunately the FA-101 is not as good as the PCI board LynxTwo. The
>data
>I presented about the FA-101 has two meanings:
>
>1 - the frequency response is not flat: -23 dB at 90 kHz is a lot
>because
>signals at that frequency are weak by their own and the transducer are
>not
>very sensitive and often are very noisy.
>Though, the attenuation could be compensated by equalization if the
>anti-alising filtering is good.
>
>2 - unfortunately the a-a filter is very soft and signals or harmonics
>extending over the Nyquist frequency, that is half of the sample rate,
>can
>be "reflected" below Nyquist and "contaminate" the recording with
>artifacts.
>
>Now I'm willing to know how the other 192 kHz devices behave.
>Testing the frequency response and the a-a filters is quite easy if you
>have a signal generator ranging up to 200 kHz!
>Any measure on other devices will greatly appreciated!
>
>Gianni
>
>
>
>------------------------------------------------------------------------
>---------------
>Centro Interdisciplinare di Bioacustica e Ricerche Ambientali
>Universita' degli Studi di Pavia
>Email
>Web http://www.unipv.it/cibra
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--
Rob Danielson
Film Department
University of Wisconsin-Milwaukee
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