[Top] [All Lists]

Re: Bat detector calibration

Subject: Re: Bat detector calibration
From: "Gianni Pavan" gpavan1960
Date: Fri Mar 18, 2016 4:43 am ((PDT))
hi all,
   sound boards, either integrated on the motherboard or connected
externally, can produce sounds in the range allowed by the supported
sampling rates. Unfortunately, starting with windows 7, there is an often
obscure intermediate step managed by the operating system. Whatever we send
to the sound output is resampled internally according to the settings in
the control panel. If we have a 192 kHz sound board, to use it at that
sample rate for either input or output we need to open the advanced
properties of the selected recording or playback device to set the sample
rate and bit depth we want to use. If we set 192k and in our software we
play at 44100 then the stream will be up sampled to 192k; viceversa, if the
playback device is set to 44100, when we send a stream at 192k it will be
down sampled to 44100. This happens for both recording and playback !
Moreover the latest windows versions have an internal level control and
this means that you're never sure of the levels you record with your

All these problems can be solved by using software that uses WASAPI that
allows a more direct control on the sound devices. Unfortunately WASAPI is
much more complex than the old wave i/o programming modes used by most

Further comments and/or corrections on this issue are welcome


2016-03-18 10:11 GMT+01:00  [naturerecordists] =

> > Almost all the codec on the market (herein included the ones on the PC)
> resample the signal so they cannot generate signal much over the audible
> range.
> Hmmm, in my personal experience most computer audio Interfaces (both
> external USB devices and even the onboard systems on the mainboards) that
> offer a playback sample rate of 192 kHz can also generate ultrasounds up =
> over 80 kHz. The frequency response may not be perfect, but it should wor=
> fine for calibrating the frequency dial of analog heterodyne bat detector=
> I just tried it once again successfully on my Windows 10 Desktop PC that
> has an onboard "Realtec High Defition Audio" device....
> Regards,
> Raimund

Centro Interdisciplinare di Bioacustica e Ricerche Ambientali
Universit=E0 degli Studi di Pavia
Via Taramelli 24, 27100 Pavia

"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.

Yahoo Groups Links

<*> To visit your group on the web, go to:

<*> Your email settings:
    Digest Email  | Traditional

<*> To change settings online go to:
    (Yahoo! ID required)

<*> To change settings via email:

<*> To unsubscribe from this group, send an email to:

<*> Your use of Yahoo Groups is subject to:


<Prev in Thread] Current Thread [Next in Thread>

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the naturerecordists mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU