Almost every PC or Pocket PC have a built-in sound
card. Sound cards
are usually treated as an
audio input and output devices for recording,
synthesizing, and replaying speech, music and
songs. However, sound
cards can do more than
that.
From instrumentation and control point
of view, a sound Card is a dual
-channel A/D
and dual-channel D/A device, which has a flat frequency
response in audio frequency range and have a
sampling rate of up to
192kHz, sampling depth
of up to 24 bits. Even without any external
attenuation circuit, it is able to measure a signal
from down to 1 uV
to 1V, thanks to its built-in
gain control (like Mic Boost, Mic Volume
and
Line Volume).
Measurement accuracy depends
on its hardware quality. Normally, an
internal
standalone sound card is better than an on-board
sound card (
chip), and an external sound card
is the best. Professional grade sound
card is
better than consumer grade sound card. In terms
of price, even
the professional grade sound
card is much cheaper (a few times
normally)
than its peers in A/D and D/A cards.
The
accuracy of the clock reference is 0.00x% typically
for an ordinary
sound card. For example, a 0.003%'s
inaccuracy in a sampling rate of
44100 Hz means
an error of only 1.3Hz. The noise level of a good
sound
card can be below -100dB, THD below 0.0029%.
So, what can be measured by a sound card. Well,
it can measure any
signal perfectly within audio
frequency range, like vibration signal,
rotational
speed, heat and Lung sound, ECG....., depending
on the
sensor used, and of course, depending
on the software used. A good one
can be found
at:
http://www.virtins.com. It is FREE to download
and
try.
website:
http://www.virtins.comPC version:
http://www.virtins.com/SCMISetup.exe Pocket
PC version:
http://www.virtins.com/PocketINSSetup.exe
Virtins Sound Card MultiInstrument consists
of a sound card dual trace
oscilloscope, a real
time spectrum analyzer, and a signal generator and
can run them concurrently. It features a specially
designed data
acquisition approach, which is
able to monitor the input signal
continuously
without missing any trigger event before a frame
of data
is collected. It has a very fast screen
refresh rate. It supports
sophisticated triggering
method including pre-trigger and post-trigger.
A comprehensive range of functions are provided,
including waveform
addition and subtraction,
Lissajous Pattern, transient signal
recording,
voltmeter, RMS amplitude spectrum, relative amplitude
spectrum, octave analysis(1/1,1/3,1/6,1/12,1/24),THD,
THD+N, SNR,
SINAD, peak hold, phase spectrum,
auto correlation, cross correlation,
function
generation, multitone generation, arbitrary waveform
generation, white noise and pink noise generation
and sweep signal
generation. It Supports 8,
16, 24 bits and multilingual user interface,
including English, French, German, Italian, Spanish,
Portuguess,
Simplified Chinese, Traditional
Chinese, Japanese, and Korean
