I'm cc'ing this back to the help list to keep a record of my errors.
As far as I can tell from the micasb schematic there is no pre-filter
on the raw mic signal to the ADC. The filter shown seems to only go
to the tone decoder chip, and doesn't look like it has any programmable
tuning. There do seem to be options to solder in resistors to use the
filter on the raw signal. I haven't seen any description of how that
filter is tuned either. But I could be wrong about it all...
If there is no filtering then you just have to rely on 'bad' freq
response in the mic and pre-amps. And you can hope that you don't
have much energy above 2Khz so you won't get a lot of aliasing.
You might also mitigate it by using the longest ADC sample clock
you can get away with. YMMV.
I don't know of any example code, other than apps/HighFrequencySampling
which I don't think uses the mic. Many have tried and some seem to
have been successful, so maybe someone else on this list will cough up
some demo code...
MS
sudheer kumar wrote:
Yes, I am using micasb. So the bandwidth is preset to 4 KHz? In case
you know of some sample code of raw mic signal sampling and recording,
please let me know. Thanks for the response.
Sudheer
On 5/6/07, *Michael Schippling* <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
what sensor board are you using?
if it's the micasb, there doesn't seem to be any way to pre-filter
the raw mic signal.
MS
sudheer kumar wrote:
> I need to sample the acoustic signal at 4 k samples/sec for a
project.
> how can I set the microphone filter bandwidth to 2 KHz. Somebody
please
> help me.
> Sudheer
>
>
>
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