Non-fluctuation interference rejection using an adaptive filter based on spectrum envelope analysis

Objectives. The rapid advancement of wireless technologies, including IoT and 5G/6G, is accompanied by an increase in the overall level of electromagnetic interference. This sets engineers the task of developing effective methods to suppress such interference, including especially challenging non-fluctuating interference of various kinds. The study aims to implement and analyze the effectiveness of a non-fluctuation interference rejection method using an adaptive filter based on spectrum envelope analysis.
Methods. Mathematical modeling, spectral analysis, and adaptive filtering methods are used in the work. The described approach is based on spectrum envelope extraction for identification and subsequent suppression of nonfluctuation interference.
Results. The effectiveness of an adaptive algorithm for suppressing non-fluctuation interference based on the analysis of the spectrum envelope has been demonstrate. This algorithm can be used as a means for isolating the envelope of the interference spectrum to enable the formation of the amplitude-frequency response of the notch filter in real time. Processing methods for three types of non-fluctuation interference were implemented and tested: harmonic, frequency-shift keying (FSK), and phase-shift keying (PSK). A signal with quadrature amplitude modulation forms a useful signal for the purposes of the study. The experimental results demonstrate the good efficiency of the proposed method. The developed adaptive notch filter based on spectrum envelope analysis is highly effective in combating harmonic interference to achieve energy gains of 8–9 dB depending on the relative intensity of interference. Notably, even as interference intensifies, the filter effectiveness persists, albeit with a slight reduction. The algorithm functions effectively under exposure to narrowband FSK and PSK interference.
Conclusions. The proposed adaptive algorithm for suppressing fluctuation interference based on spectrum envelope analysis is optimally effective in the presence of harmonic interference within the communication channel, but less effective in the presence of more broadband interference. The study is of practical importance for digital communication systems, where high noise immunity is required in a complex electromagnetic environment.

1. Savvateev Yu.I., Nazarov O.V. (Eds.). Pomekhozashchishchennost’ priema diskretnykh signalov (Noise Immunity of Reception of Discrete Signals). Moscow: Radiotekhnika; 2015. 584 p. (in Russ.). ISBN 978-5-93108-094-9

2. Borisov V.I., Zinchuk V.M. Pomekhozashchishchennost’ sistem radiosvyazi. Veroyatnostno-vremennoi podkhod (Noise Immunity of Radio Communication Systems. Probabilistic-Temporal Approach). Moscow: RadioSoft; 2008. 260 p. ISBN 5-93274-011-6 (in Russ.). https://www.elibrary.ru/catzhm

3. Parshutkin A.V., Maslakov P.A. Noise stability of sattelite communication channels with amplitude-phase modulation to exposure to urged unsteady interference. Voprosy oboronnoi tekhniki. Seriya 16. Tekhnicheskie sredstva protivodeistviya terrorizmu = Military Enginery. Counter-Terrorism Technical Divices. Issue 16. 2019;11–12:96–101 (in Russ.).

4. Lozhkin K.Yu., Petrov A.V., Mironov V.A., Mikhalev V.V., Prozhetorko S.S. Analytical dependences of bit distortion average probability M-QAM of a signal against harmonic or PSK jamming subject to fading. Radiotekhnika = Radioengineering. 2020;84(4–8):27–35 (in Russ.). https://doi.org/10.18127/j00338486-202004(8)-03

5. Kulikov G.V., Nesterov A.V., Lelyukh A.A. Interference immunity of reception of signals with quadrature amplitude shift keying in the presence of harmonic interference. Zhurnal Radioelektroniki = Journal of Radio Electronics. 2018;11:2 (in Russ.). https://doi.org/10.30898/1684-1719.2018.11.9

6. Kulikov G.V., Lelyukh A.A., Batalov E.V., Kuzelenkov P.I. Noise immunity of reception of signals with quadrature amplitude modulation in the presence of interference phase-shift keying. Zhurnal Radioelektroniki = J. Radio Electronics 2019;7 (in Russ.). Available from URL: http://jre.cplire.ru/jre/jul19/10/text.pdf, https://doi.org/10.30898/1684-1719.2019.7.10

7. Kulikov G.V., Shamshura A.O., Pechenin E.A., Shatalov E.V. Analysis of the noise immunity of receiving signals with quadrature amplitude modulation against the background of frequency-shift keyed interference. Vestnik Voronezhskogo instituta FSIN Rossii = Vestnik of Voronezh Institute of the Russian Federal Penitentiary Service 2022;2:9–15 (in Russ.).

8. Widrow B., Stearns S.D. Adaptive Signal Processing. Prentice-Hall; 1985. 474 p. [Widrow B., Stearns S.D. Adaptivnaya obrabotka signalov (Adaptive Signal Processing): transl. from Engl. Moscow: Radio i svyaz’; 1989. 439 p. (in Russ.). ISBN 5-256-00180-9]

9. Farhang-Boroujeny B. Adaptives Filters: Theory & Applications. Wiley, UK; 1998. 529 p.

10. Shynk J.J. Frequency-domain and multirate adaptive filtering. IEEE Signal Process. Mag. 1992;9(1):14–37. https://doi.org/10.1109/79.109205

11. Popov D.I. Analysis of recursive rejection filters in transient mode. Izvestiya Tul’skogo gosudarstvennogo universiteta. Tekhnicheskie nauki = Proceedings of Tula State University. Technical Sciences. 2023;4:259–264. https://www.elibrary.ru/guzddw

12. Popov D.I. Optimization the parameters of recursive notch filters. Izvestiya vysshikh uchebnykh zavedenii. Povolzhskii region. Tekhnicheskie nauki = University Proceedings. Volga Region. Engineering Sciences. 2022;2(62):26–35. https://doi.org/10.21685/2072-3059-2022-2-2, https://www.elibrary.ru/fcnxab

13. Kulikov G.V., Konyashkin G.V. Adaptive Notch Filter for Non-Fluctuation Interference Suppression: RF Pat. 232764 U1. Publ. 19.03.2025.

14. Friedlander B., Porat B. The Modified Yule-Walker Method of ARMA Spectral Estimation. IEEE Transactions on Aerospace Electronic Systems. 1984;AES-20(2):158–173. https://doi.org/10.1109/TAES.1984.310437

15. Solonina A., Ulakhovich D. Algoritmy i protsessory tsifrovoi obrabotki signalov (Algorithms and Processors of Digital Signal Processing). St. Petersburg: BHV-Petersburg; 2002. 464 p. (in Russ.).

16. Nguyen Tien Phat. Obrabotka radiotekhnicheskikh signalov na fone pomekh (Processing of Radio Signals Against the Background of Interference). Monograph. Le Kui Don Vietnam State Technical University. Tambov: Konsaltingovaya kompaniya Yukom; 2018. 76 p. (in Russ.). https://www.elibrary.ru/xoyrql