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
Kirt
