INVESTIGATION OF THE USE OF A SOUND CARD FOR REGISTERING LOW-FREQUENCY PULSE SIGNALS
N.Y. Kudryashov, V.A. Kuklin, K.Y. Trifonov
The article is devoted to the problem of creating accessible information and measurement systems for carrying out experimental research work, with flexible software and hardware reorganization of the algorithm for recording analog signals and processing measurement results. Using the capabilities of converting analog signals to a PC’s sound card for these purposes greatly simplifies the structure of such a system. However, the field of its application for recording pulsed signals has not been studied sufficiently. Simulation of the process of transformation and digitization of rectangular pulses by the audio channel of a personal computer showed significant distortions in their form. The analysis of methods for averaging fluctuations for reconstructing the amplitude of registered impulse signals is analyzed. It was found that averaging over a period of half the peak value of the distorted pulses practically eliminates the systematic error of the preliminary processing. t is also revealed that the final value of the ADC sampling frequency leads to an averaging error, which, when using modern sound cards, does not exceed 5% when recording impulse signals in the frequency range up to 5-7 kHz. The amplitude and frequency characteristics of such a registration channel are investigated. Analysis of the research results showed that the audio channel of a personal computer can be used in information and measurement systems for recording pulse signals with amplitude up to 0.5 V.
Keywords: : pulse signal, sound card, pulse photometry, nephelometry.