[linux-audio-user] High sample rate cards

[Tim Howard]

st wrote:
> BJaY wrote:
> > Hi,
> >       I'm looking to do some high sample rate stuff - 500kHz or more
>
> Where did you get a microphone and preamp that would respond at
> that frequency?  You will be up into maritime radio communication
> band, approaching AM radio band.  I wonder if you will have problems
> with interference.
>

Common misconception...  Very high frequency audio does not equal
electromagnetic radiation (radio, etc.).  Audio is the compression and
expansion of air, so it isn't really affected by EMI.

Are you using another ultrasonic transducer to receive the signal?  Is
it necessary to capture the entire waveform, or just the envelope?  If
you need an accurate waveform, your best bet would likely be to build
your own A/D circuit.  Otherwise, rectify it, use an LP filter, and
you're good to go.

TimH