Editing Sound card (section)

=== Non-sound uses ===
Sound cards can be used to generate (output) arbitrary electrical waveforms, as any digital waveform ''played'' by the soundcard is converted to the desired output within the bounds of its capabilities. In other words, sound cards are consumer-grade [[arbitrary waveform generator]]s. A number of free and commercial software allow sound cards to act like [[function generator]]s by generating desired waveforms from functions;<ref>{{Cite web |url=http://www3.telus.net/Harley_Davidson/oscilloscope/Downloads.html |title=Web page with free function generator and oscilloscope software for sound card |access-date=2012-04-03 |archive-date=2012-04-27 |archive-url=https://web.archive.org/web/20120427131203/http://www3.telus.net/Harley_Davidson/oscilloscope/Downloads.html |url-status=dead }}</ref> there are also online services that generate audio files for any desired waveforms, playable through a sound card.

Sound cards can also be used to record electrical waveforms, in the same way it records an analog audio input. The recording can be displayed by special or general-purpose audio-editing software (acting as an [[oscilloscope]]) or further transformed and analyzed. A protection circuit should be used to keep the input voltage within acceptable bounds.<ref name=Bogatin>{{cite web |url=https://www.nutsvolts.com/magazine/article/turn-your-computers-sound-card-into-a-scope |author=Eric Bogatin |title=Turn Your Computer’s Sound Card into a Scope|quote=For example, the Sabrent low cost ($8) USB sound card has an internal 16-bit ADC that can sample up to 196 kS/sec, but has a limited input frequency range from about 100 Hz to 20 kHz. The Waveforms software tool can drive this USB sound card.}}</ref><ref name="Pervaiz10">{{cite web |last1=Pervaiz |first1=Saad |title=Use of Sound Card as an Oscilloscope and Function Generator |url=https://physlab.org/wp-content/uploads/2016/04/Sound_Card.pdf |date=Winter 2010}}</ref>

As general-purpose waveform generators and analyzers, sound cards are bound by several design and physical limitations.
* Sound cards have a limited sample rate, typically up to 192&nbsp;kHz. Under the assumptions of the [[Nyquist–Shannon sampling theorem]], this means a maximum signal frequency (bandwidth) of half that: 96&nbsp;kHz. Real sound cards tend to have a bandwidth smaller than implied by the Nyquist limit from internal filtering.<ref name=Bogatin/>
* As with all ADCs and DACs, sound cards produce distortion and noise. A typical integrated sound card, the [[Realtek]] ALC887, according to its data sheet has distortion about 80&nbsp;dB below the fundamental; cards are available with distortion better than −100&nbsp;dB.
* Sound cards commonly suffer from some clock drift, requiring correction of measurement results.

Sound cards have been used to analyze and generate the following types of signals:

* '''Sound equipment testing'''. A very-low-distortion sinewave oscillator can be used as input to equipment under test; the output is sent to a sound card's line input and run through [[Fourier transform]] software to find the amplitude of each harmonic of the added distortion.<ref>[http://www.diyaudio.com/forums/solid-state/166378-sound-card-software-use-distortion-measurement-2.html Detailed discussion of distortion measurement with sound cards], including suitable cards and software</ref> Alternatively, a less pure signal source may be used, with circuitry to subtract the input from the output, attenuated and phase-corrected; the result is distortion and noise only, which can be analyzed.
* '''Gamma spectroscopy'''. A sound card can serve as a cheap [[multichannel analyzer]] for [[gamma spectroscopy]], which allows one to distinguish different radioactive isotopes.<ref>{{cite conference |last1=Ibrahim |first1=Maslina Mohd |last2=Yussup |first2=Nolida |last3=Lombigit |first3=Lojius |last4=Rahman |first4=Nur Aira Abdul |last5=Jaafar |first5=Zainudin |title=Development of multichannel analyzer using sound card ADC for nuclear spectroscopy system |date=2014 |pages=50–53 |doi=10.1063/1.4866103|conference=International Nuclear Science, Technology & Engineering Conference 2013 (iNuSTEC2013)}}</ref>
* '''Longwave radio'''. A 192&nbsp;KHz sound card can be used to receive radio signals up to 96&nbsp;kHz. This bandwidth is enough for longwave [[time signal]]s such as the [[DCF77]] (77.5&nbsp;KHz). A coil is attached to the input side as an antenna, while special software decodes the signal.<ref>[http://pwet.fr/man/linux/commandes/dcf77rx/ man dcf77rx (Commandes) - soundcard DCF77 (and HBG) beacon receiver]</ref><ref>[http://www.qsl.net/dl4yhf/speclab/timesigs.htm Time Signal Decoder]</ref> A sound card can also work in the opposite direction and generate low power time signal transmissions ([[JJY]] at 40&nbsp;KHz, using harmonics).<ref>{{cite web |title=Fukushima: online JJY time signal emulator |url=https://jjy.luxferre.top |website=jjy.luxferre.top}}</ref>