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Re: RE: [naturerecordists] freq response and aliasing of Edirol F=

Subject: Re: RE: [naturerecordists] freq response and aliasing of Edirol F=
From: Gianni Pavan <>
Date: Fri, 13 Aug 2004 23:23:24 +0200
A-101 at 192 kHz

Rob,
         in my first test I just looked at frequency response and a-a
filters. At standard frequencies (44, 48, 96) the FA 101 worked as
expected, but I did not make accurate measures as I did with 192 kHz.

Gianni

At 21.53 13/08/2004, you wrote:

>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 emittin=
g
> >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
> >
> >
> >
> >------------------------------------------------------------------------
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> >Universita' degli Studi di Pavia
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>
>--
>Rob Danielson
>Film Department
>University of Wisconsin-Milwaukee
>
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>

---------------------------------------------------------------------------=
------------
Centro Interdisciplinare di Bioacustica e Ricerche Ambientali
Universita' degli Studi di Pavia
Email     
Web       http://www.unipv.it/cibra



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