Improving the Automatic Frequency Tracking and Correction System of Pulse Radars with Magnetron Transmitter

Introduction. In conventional pulse radar systems of earlier generations that utilize magnetron generators, automatic frequency tracking and correction mechanisms are predominantly based on analog technology. These systems exhibit several inherent limitations, most notably those arising from to the limited frequency stability of the magnetron generator. Specific issues include inaccuracies in estimating the deviation between the measured frequency and its nominal value, a limited tracking range, and a slow response time. The fundamental cause of this low frequency stability lies in the magnetron design, which operates on an LC self-oscillation principle. In this paper, we propose to enhance the automatic frequency tracking and correction system by incorporating digital signal processing techniques and fast Fourier transform (FFT) algorithms. This approach enables rapid and high-precision measurement of the operating frequency within time intervals defined by the pulse width. The proposed methodology significantly improves the performance and reliability of such systems. These findings hold considerable practical importance, particularly for the modernization and sustained operation of legacy pulse radar systems. By addressing the limitations of outdated analog components, the proposed solution extends the operational lifespan of such systems. This is of importance given the scarcity of replacement parts that are no longer available on the market.

Aim. Research and presentation of a digital solution for the system of automatic frequency tracking and correction.

Materials and methods. The research methodology was based on previous research findings, achievements in digital signal processing and theoretical analysis. A structural diagram of the proposed system was developed and its experimental simulation was conducted.

Results. A functional diagram of the proposed automatic frequency tracking and correction system is developed. Specific experimental results are described. The measurement error can reach 1 kHz (~0.003 %) in the mid-frequency range.

Conclusion. An automatic frequency tracking and correction system has been developed. This approach extends the current methodology in the field of pulse radars.

1. Atlam systems. Magnotron Automatic Frequency Control (AFC) System. Available at: https://www.altamsys.com/portfolio/magnetron-afc/ (accessed 09.04.2025)

2. Skolnik M. I. Introduction to Radar Systems. 2nd ed. New York, McGraw-Hill, 1980, 581 p.

3. Tyapkin V. N., Fomin A. N., Garin E. N., Fateev Yu. L., Berdyshev V. P., Nogovitsyn A. A., Temerov A. V., Somov V. G., Lyutikov I. V. Osnovy postroeniya radiolokatsionnykh stantsii radiotekhnicheskikh voisk: uchebnik [Fundamentals of Construction of Radar Stations for Radiotechnical Troops: Textbook]. Krasnoyarsk, Sib. feder. un-t, 2011, 536 p. (In Russ.)

4. Ilarionov Yu. A., Raevsky A. S., Raevsky S. B., Sedakov A. Yu. Ustroistva SVCH- i KVCH -diapazonov. Metody rascheta. Algoritmy. Tekhnologii izgotovleniya [Microwave and EHF Range Devices. Calculation Methods. Algorithms. Manufacturing Technologies]. Moscow, Radio engineering, 2013, 752 p. (In Russ.)

5. Kubov V. LC-bridge Oscillator Frequency Characteristics. Experiment Findings. 2024, pp. 1–7. doi: 10.13140/RG.2.2.13351.15520

6. Kaganov V. I. Radioelektronnye sistemy avtomaticheskogo upravleniya [Electronic Automatic Control Systems]. Moscow, Goryachaya liniya. Telekom, 2009, 432 p. (In Russ.)

7. Automatic Frequency Control. Available at: https://www.radartutorial.eu/09.receivers/rx11.en.html (accessed 09.04.2025)

8. P-37. Available at: https://rtv-pvo-gsvg.narod.ru/doc/P_37_TO.pdf (accessed 09.04.2025)

9. PRV-13. Available at: https://rtv-pvo-gsvg.narod.ru/doc/Prv_13.pdf (accessed 09.04.2025)

10. Ermak S. N., Sokolov A. N., Nazarov D. G. Radiolokatsionnye sistemy voennogo naznacheniya. Osobennosti ekspluatatsii i primenenie PRV-13 [Military Radar Systems. Operation and Application Features of the PRV13]. Minsk, BSUIR, 2019, 202 p. (In Russ.)

11. Skripkin N. I., Morugin S. L. Frequency Tuning of a Magnetron of the 3-mm Wavelength Range Using an Additional Output. Instruments and Experimental Technology. 2018, no. 4, pp. 516–520.

12. Borisova N. A. The Emergence of Radar in Different Countries: Comparative-Historical Analysis. Genesis: Historical Research. 2020, no. 7, pp. 51–73. (In Russ.) doi: 10.25136/2409-868X.2020.7.33501

13. Mytsenko I. M., Khalameida D. D. System of Automatic Frequency Control of Heterodyne of Radar Receiver with Magnetron Transmitter. Radiofizika i Elektronika. 2018, vol. 23, no. 2, pp. 48–53. (In Russ.) doi: 10.15407/rej2018.02.048

14. Chukhlomin I. E., Trubnikov A. V., Lashkevich G. Yu. The Automatic Digital Adjustment System of a Receiver Local Oscillator's Frequency Analysis to a Magnetron Pulsed Transmitter's Carrier. J. of Radio Electronics. 2022, no. 11, pp. 1–16. (In Russ.) doi: 10.30898/1684-1719.2022.11.10

15. Yachum N., Russamee N., Srisertpol J. Automatic frequency control of the magnetron system for medical linear accelerator using fuzzy logic control. Proc. of XLVI Int. Summer School Conf. APM. 2018, pp. 275–285.

16. Gonzalez R. C., Woods R. E. Digital Image Processing. 3 rd Ed. New Jersey, Prentice-Hall, 2007, 976 p.

17. Sungsu Cha, Seung Hyun Lee, Hyung Dal Park, Ki Beak Song. Development of an Automatic Frequency Measurement System for RF Linear Accelerator Magnetrons. J. of the Korean Physical Society. 2015, vol. 66, no. 11, pp. 1664–1668. doi: 10.3938/jkps.66.1664

18. Kutsko D. I., Polzunov V. V. Analiz raboty generatora s dopolnitel'noi obratnoi svyaz'yu [Analysis of the Operation of a Generator with Additional Feedback]. Available at: https://libeldoc.bsuir.by/bitstream/123456789/36080/1/Kutsko_Analiz.pdf (accessed 09.04.2025)

19. Discover What's New. Available at: https://www.mathworks.com/products/new_products/latest_features.html (accessed 09.04.2025)

20. Richards M. A., Scheer J. A., Holm W. A. Principles of Modern Radar. Vol. I: Basic Principles. New Jersey, SciTech Publishing, 2010, 924 p.

21. Besgina I. P., Erjomka V. D., Makulina T. A., Mytsenko I. M. Current-Less Tuning and Control of Self-Oscillations Frequency Terahertz Range Klynotron. Izvestiya VUZ. Applied Nonlinear Dynamics. 2015, vol. 23, no. 6, pp. 47–60. (In Russ.)

22. Bezgina I., Yeremka V., Mitsenko I., Yeremka D., Halameida D. Automatic Frequency Control System of a Pulsed Magnetron. Radiofizika i elektronika. 2019, vol. 24, no. 3, pp. 61–66. (In Russ.) doi: 10.15407/rej2019.03.061

23. Automatic Frequency Adjustment When Measuring S-Parameters of Converters Using Vector Network Analyzers Manufactured by JSC NPF MIKRAN. Available at: https://www.micran.ru/about/blog/avtomaticheskaya-podstroyka-chastoty-pri-izmerenii-sparametrov-konvertorov-s-pomoshchyu-vektornykh-/ (accessed 09.04.2025)

24. Methods of Interpolation and Approximation. Available at: https://portal.tpu.ru/SHARED/m/MBB/uchebnaya_rabota/Model/Tab/Interp_app.pdf (accessed 09.04.2025)