I've now tried 6 computers, and can't get any of them to output higher than=
about 20kHz. I asked the same question on the Audacity forum, and got this=
response "Most soundcards have anti-aliasing filters to keep them from goi=
ng beyond audibility (20KHz)."
I'm thinking that either I'm doing something wrong (quite likely), or suita=
ble sound cards aren't that common.
I think I will have to try Ivano's suggestion of the signal generator.
Peter Shute
Sent from my iPad
On 18 Mar 2016, at 8:11 PM, <raimundspec=
> [naturerecordists] <<mai=
lto:>> wrote:
> Almost all the codec on the market (herein included the ones on the PC) r=
esample the signal so they cannot generate signal much over the audible ran=
ge.
Hmmm, in my personal experience most computer audio Interfaces (both extern=
al USB devices and even the onboard systems on the mainboards) that offer a=
playback sample rate of 192 kHz can also generate ultrasounds up to over 8=
0 kHz. The frequency response may not be perfect, but it should work fine f=
or calibrating the frequency dial of analog heterodyne bat detectors.
I just tried it once again successfully on my Windows 10 Desktop PC that ha=
s an onboard "Realtec High Defition Audio" device....
Regards,
Raimund
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