Nice. Is there a limit on the length of the wav file? And can you save the =
heterodyned sounds? David could just mix it into his recording.
Peter Shute
Sent from my iPad
On 20 Feb 2016, at 8:58 PM, <raimundspec=
> [naturerecordists] <<mai=
lto:>> wrote:
> I bought a "Discovery Kids Ultrasonic Detector" on eBay for about $40. It=
's a heterodyne detector, and is of course a toy compared to some, but it s=
eems to work ok. I suspect though, that a software solution would be better=
.
This kind of heterodyne functionality is available in the free Avisoft-SASL=
ab Lite software (http://www.avisoft.com/downloads.htm). Just open the .wav=
file and activate the option "enable heterodyned playback" from the menu "=
File"/"Heterodyned Playback mode...", where the center frequency and bandwi=
dth can be adjusted. If you then play the file by clicking at the play butt=
on, you will hear the heterodyned signal just like on an analog heterodyne =
bat detector.
The same software also allows to down-shift portions of a waveform using FF=
T (command "Edit"/"Filter"/"Frequency Domain Transformation..." > "Frequenc=
y Shift").
The SASLab Pro version (which is unfortunately not free) would also allow r=
e-synthesizing any whistle-like sounds using its Graphic Synthesizer tool, =
which allows modifying time and frequency scales independently.
Regards,
Raimund
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
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