using voice input of pc

[kkrish]

Hi all,
Is it possible to use the mic input of a pc to capture an
analog signal and convert it into digital signal using the voide
processing circuit of the PC?I browsed the net and asked the question
in arch.embedded but I did not get any specific answer.Is it not
possible to convert analog signals of frequency other than the voice
frequency into digital form?

thanks in advance.
Krishna.V.J

 

[Mark Fortune]

Hi all,
Is it possible to use the mic input of a pc to capture an
analog signal and convert it into digital signal using the voide
processing circuit of the PC?

That's basically what happens when you record a .wav file

I browsed the net and asked the question

in arch.embedded but I did not get any specific answer.Is it not
possible to convert analog signals of frequency other than the voice
frequency into digital form?

thanks in advance.
Krishna.V.J

depends very much on what sound card you have. Most of them I suspect go
up to about 20KHz since thats all you need for the human hearing range.

There are quite a few software packages out there that allow you to use
the mic or line in of your sound card as a rudimentary oscilloscope or
data logger.. which I suspect is something you are trying to do, but I
wouldnt expect it to have a very wide range, or cope with DC voltages.

Mark

 

[Jamie]

Hi all,
Is it possible to use the mic input of a pc to capture an
analog signal and convert it into digital signal using the voide
processing circuit of the PC?I browsed the net and asked the question
in arch.embedded but I did not get any specific answer.Is it not
possible to convert analog signals of frequency other than the voice
frequency into digital form?

thanks in advance.
Krishna.V.J

yes, not DC but an AC wave can be captured and analyzed via
a few forms. Sine Wave crossing, DFT, FFT etc...
the first basic step is to learn how to code so that you can
actually get your sound card to switch into record mode and
pass to your application the blocks of samples the sound system
is collecting which is put in PCM (Pulse coded Modulation) format.

 

[Tomi Holger Engdahl]

Hi all,
Is it possible to use the mic input of a pc to capture an
analog signal and convert it into digital signal using the voide
processing circuit of the PC?

The answer is yes if your signal you have and/ot part you are
interrested in is within the sound card supported frequency
range. generally frequencies from few hundred Hz to few kHz
be recorded more or less at useable quality on mic input
but the frequency response might not be flat
(outside this the signals the signal ca attenuate considerably).

When usign line input you generally get around 20 Hz to 20 kHz
with pretty flat frequency response.

I browsed the net and asked the question
in arch.embedded but I did not get any specific answer.Is it not
possible to convert analog signals of frequency other than the voice
frequency into digital form?

Soundcards are not detected to handle frequencies outside normal
audio frequencies (20 Hz to 20 kHz). Those higher and lower frequencies
are intentionally filtered out on soundcard circuitry before
actual analogue to digital conversion.

With some hardware modifications at least some sound cards
can be adapted to accept frequencies down to DC:

Sound card based multimeter
http://www.qsl.net/om3cph/sb/dcwithsb.htm
This web page describes how to modify Sound Blaster AWE-64 and SB16 to
accept DC signals into their A/D-converter. With suitable software
this allows a sound card to be used as a simple multimeter or
oscilloscope that can measure also DC signals. There ideas described
here sould be also adaptable to other sound card models as well.