Virtual sound card sine wave audio signal generator

Nowadays, the sound card in personal computers is already a standard configuration. Through the sound card, the PC can not only output music or language signals, but by writing a program, the PC can also output sine wave audio signals through the sound card, using the PC as a sine wave audio signal generator. It can meet the requirements of general electronics enthusiasts for use as a sine wave audio signal generator. This article introduces readers to the utility program designed by the author to achieve this function and its design method.

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This program is designed using VC++6.0, and its interface is a standard Windows interface. Its characteristic is that it can continuously output sine wave audio signals without interruption, unlike other programs with similar functions that always output signals. There is an intermittent phenomenon, and signals of multiple frequencies can be output at the same time.

Function introduction

1． Frequency output range: 1Hz-20KHz;
2. Sound card sampling frequency settings: 8000Hz, 11025Hz, 22050 Hz, 44100 Hz, 48000 Hz, 64000 Hz, 88200 Hz, 96000Hz;
3． Continuously output sine wave audio signals without interruption;
4. When timing output, continuous output time setting: 1 second - 5 hours;
5. Simultaneously output signals of multiple frequencies.
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Hardware requirements

The sound card hardware and its driver need to be installed.

Hardware connection and program usage

Use a single-core audio shielded cable to connect to a stereo plug with a diameter of 3.5mm. The core wire of the cable is connected to the top contact of the plug, and the shielding layer of the cable is connected to the bottom contact of the plug. Then, insert the stereo plug into the line output (LINE OUT) or speaker output (SP) of the sound card and output the signal through the cable.
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Open the resource manager, copy the executable file lcysine.exe provided by the author to a folder in the PC, double-click the file name with the left mouse button to run the file, and then operate according to the Chinese character prompts on the program interface , the left and right channels of the sound card can continuously output sine wave audio signals at the same time.

If you find that the signal output is intermittent, there is a problem with the sound card's sampling frequency setting: first, the value is too high and the sound card does not support it. For example: the sound card's maximum supported sampling frequency is 22050Hz, but you set it to 44100Hz. It exceeds the maximum sampling frequency supported by the sound card; secondly, although the set sampling frequency does not exceed the maximum sampling frequency supported by the sound card, the set frequency value is not supported by the sound card. When setting the sampling frequency, it is best to set it to the highest frequency value supported by the sound card. This value can be obtained from the sound card manual, so as to achieve the best quality of the output signal. It doesn’t matter if you don’t know the highest frequency value supported by the sound card. After the program is run, several data are provided on the screen. They are the sampling frequency values ​​supported by most sound cards. You can choose one so that your sound card can continuously output signals. the highest value.
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The quality of signal output is related to the ratio of sampling frequency/output frequency. The larger the ratio, the higher the quality; the smaller the ratio, the lower the quality. The higher the quality of the sound card, the higher the sampling frequency it supports. Therefore, a high-quality sound card can output better-quality signals than a low-quality sound card.
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Adjust the amplitude of the output signal. Use the left mouse button to click the small speaker icon on the lower right corner of the screen. A control for adjusting the output signal size will appear. Adjust the slider on the control to adjust the output signal size.

If you want to output signals of multiple frequencies at the same time, you can run the program multiple times, that is, double-click the executable file of the program and run the program once to make the sound card output signals according to your settings without closing the program; double-click the program again. The executable file of the program, run the program again to make the sound card output signals at the same time according to your second setting method. In this way, signals of two frequencies can be output simultaneously. Run the program multiple times according to the above operation method, and you can output signals of multiple frequencies at the same time.

Furthermore, this program can also run simultaneously with the program introduced in the article "Sound Card Oscilloscope and Spectrum Analyzer" in the August 2003 issue of this magazine or "Sound Card Digital Frequency Meter" in the September 2003 issue. Run this program without closing it and then run the program introduced in the article "Sound Card Oscilloscope and Spectrum Analyzer", and you will be able to have the functions of a sine wave audio signal generator and an oscilloscope and spectrum analyzer on one PC; run this program without Close this program and then run the program introduced in the article "Sound Card Digital Frequency Meter", and you will be able to have both the sine wave audio signal generator and digital frequency meter functions on one PC.