I.V. Zaitsev1, D.O. Sychev2, Yu.A. Bondartsov3

1−3 MESC of the Air Forse "N.E.Zukovsky and Yu.A. Gagarin Air Force Academy" (Voronezh, Russia)

1 igorwz@mail.ru, 2 dmitry_olegovich_s@mail.com, 3 byury@mail.com

In the modern world, the development of radio receivers begins with testing the applied circuit solutions on their models. A powerful tool for this purpose is the MATLAB simulation package. MATLAB includes modules for determining the quality of digital communication systems by synchronizing and comparing transmitted and received messages either bitwise (Bit Error Rate, BER) or as whole packets (Packet Error Ratio, PER). However, it does not have a ready-made module for determining the quality of a demodulated speech signal. To assess the quality of an analog signal when creating devices for transmitting and receiving speech, it is necessary to determine the intelligibility of the transmitted information. There are both subjective and objective methods for determining the intelligibility and quality of received signals. Subjective methods have been used since the creation of transmitting and receiving devices. However, these methods have notable disadvantages, such as the significant time required to conduct research and the considerable effort demanded of the people involved. As science has advanced, efforts have emerged to address these shortcomings and to develop objective methods.

Currently, various methods used in different countries have been developed (such as the Speech Transmission Index, STI, and its modifications), but they lack statistical data for Russian speech, resulting in significant errors. It should be noted that using objective methods to assess the quality of speech transmission does not account for the frequency dependence of perception parameters of the speech signal against the background of interference in the analyzed frequency band. This disadvantage can be addressed by the method of instrumental assessment of intelligibility, which is based on the internal representation of the speech signal and the interfering effect on the duration of the quasi-stationary state of speech. This method considers the frequency dependence of perception parameters and averages them over the duration of implementation to obtain a consistent assessment.

A formant method for determining intelligibility is proposed for use. Based on the modeling of the algorithm for the instrumental calculation of formant intelligibility, it is possible to implement automatic measurement of the quality of speech information transmission when evaluating the effectiveness of solutions in radio communications. This method assesses the spectral level of the speech signal and interference in bands of equal articulation intelligibility of the received signal. To implement this method on receiving equipment, a reference test signal is required. This signal is used to compare the transmitted signal, which may be affected by unintended and intentional interference, generally of a non-additive nature. A software module has been developed that allows real-time measurements of speech intelligibility based on samples of 2-3 words or 6-8 syllables in length. This significantly reduces the time needed to test developed radio receivers, decreasing it tenfold.

Zaitsev I.V., Sychev D.O., Bondartsov Yu.A. Instrumental assessment of speech intelligibility in analog radio communication lines using MATLAB Simulink simulation package. Information-measuring and Control Systems. 2024. V. 22. № 6. P. 63−69. DOI: https://doi.org/10.18127/j20700814-202406-07 (in Russian)

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