A.S. Podstrigaev1, Tran Huu Nghi2, D.A. Kalinin3, Nguyen Trong Nhan4

1–3 Saint Petersburg Electrotechnical University «LETI» (Saint Petersburg, Russia)
4 Le Quy Don Technical University (Hanoi, Vietnam)

1 ap0d@ya.ru, 2 huunghiht@gmail.com, 3 dimk.a.a@inbox.ru, 4 10th20th30th@gmail.com

Radio monitoring complexes are used to analyze the electromagnetic situation, to control the operation of radio emission sources (RESs), to ensure electromagnetic compatibility of RESs, to control and analyze threats to the normal operation of radio electronic means. An important task in radio monitoring is to determine the type and mode of operation of RESs. For this purpose, in particular, the recognition of the type of intrapulse modulation (IPM) of signals common in practice is performed: chirp, simple pulse, binary and quadrature phase shift keying. The simultaneous operation of a large number of RESs for radio monitoring complex creates complex signal environment. It is characterized primarily by the fact that in the instantaneous analysis band of the radio monitoring complex the probability of time-overlapped pulses increases. One of the negative effects of such time-overlapping is hiding of a weak pulse in the spectrum of a powerful pulse. This prevents stable detection of the weak pulse throughout all analysis windows in which it exists. Another difficulty is the significant distortion of the envelope shape of the weak pulse. Together, these effects reduce the reliability of recognizing the type of IPM. Therefore, in this paper, an algorithm for recognizing types of IPM of time-overlapped pulses is developed. Using simulated and recorded signals, the influence of the parameters of time-overlapped pulses and signal-to-noise ratio (SNR) on the reliability of recognition is investigated. It is shown that at a difference of carrier frequencies of time-overlapped pulses not less than 10 MHz and a SNR value for the powerful pulse not less than 4 dB ratio of pulse amplitudes, providing the probability of correct recognition is not worse than a given, depends on the specified SNR value linearly. Increasing the SNR value for the powerful pulse from 4 to 14 dB leads to decrease of the amplitude ratio of weak and powerful pulses by 8.5–10 dB. At the difference of carrier frequencies of time-overlapped pulses of 10 MHz and the difference of their amplitudes of 11 dB probability of correct recognition of the weak pulse of at least 90% is provided at the SNR value for it is not less than 3 dB. At the specified parameters of pulses to recognize the type of IPM of the weak pulse, the proposed algorithm requires the SNR values only 1–3 dB higher than the previously developed algorithm. Achieving the stated quality parameters in practice will require the SNR values 1.5–3.5 dB higher due to the noise introduced during signal sampling. The obtained results can be used in the development of a signal analysis device from the composition of the radio monitoring complex.

Podstrigaev A.S., Tran Huu Nghi, Kalinin D.A., Nguyen Trong Nhan. Algorithm for recognizing types of intrapulse modulation of time-overlapped pulses. Achievements of modern radioelectronics. 2024. V. 78. № 2. P. 53–65. DOI: https://doi.org/10.18127/j20700784-202402-05 [in Russian]

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