D.V. Ivanov1, V.A. Ivanov2, M.I. Ryabova3, V.V. Ovchinnikov4

1-4 Volga State University of Technology (Yoshkar-Ola, Russia)

1 IvanovDV@volgatech.net; 2 IvanovVA@volgatech.net; 3 RyabovaMI@volgatech.net; 4 OvchinnikovVV@volgatech.net

In recent years, significant advancements have been made in technologies that enable reliable communication through wideband HF radio channels with bandwidths ranging from 3 to 48 kHz and adjacent channel steps of 3 kHz, achieving data transfer rates of up to 120 kbit/s. To support this, both software-defined radio (SDR) and cognitive radio (CR) technologies are now being implemented. However, a key challenge in ionospheric HF radio communication is the variability of its operating frequency range and the impact of factors such as intermode time-frequency dispersion and narrowband man-made interference, which negatively affect both narrowband (3 kHz) and wideband systems operating in composite narrowband subchannels. This paper examines the main types of time-frequency dispersion in single-mode dual-ray narrowband radio channels, as well as in single-mode and multiple-mode channels with diffuse multipath propagation. These are considered in the context of selecting a modem that ensures at least 80% availability, as well as modeling wave packet propagation through the ionosphere. Methods and techniques to mitigate these negative effects are discussed. The aim of the research was to analyze the negative effects of intermode time-frequency dispersion on HF communication systems and to explore methods and strategies for overcoming these challenges. The paper provides a scientific rationale for addressing the issue of ensuring that communication systems have data on the availability of channels affected by intermode time-frequency dispersion and man-made interference. The signal-to-noise ratio (SNR) was identified as the critical parameter that fluctuates most rapidly over geophysical time. Additionally, the paper presents an effective solution for channel diagnostics using active sensors in the 2–30 MHz range, employing SDR technology. Methods for diagnosing multiple channels and selecting those with at least 80% availability for a given modem are discussed. The paper proposes an approach and methods for mitigating the negative effects of intermode time-frequency dispersion and man-made interference through sensor diagnostics technology. It demonstrates the feasibility of adaptively selecting optimal channels from those tested, providing data on the required communication signal power and data transfer rates to enhance the overall efficiency of the communication system. Experimental results showed that the sensor diagnostics approach can yield a radiated power gain of 4–12 dB on mid-latitude paths and 5–6 dB on polar paths for a given modem or constant data rate. Furthermore, selecting channels with at least 80% availability for the modem with the highest possible data rate can increase throughput by up to 2 times during the day and night, and by 4–8 times during transition periods.

Ivanov D.V., Ivanov V.A., Ryabova M.I., Ovchinnikov V.V. Dispersion effects in ionospheric radio channels. Part 2. Types of time-frequency dispersion. Radiotekhnika. 2024. V. 88. № 11. P. 63−77. DOI: https://doi.org/10.18127/j00338486-202411-10 (In Russian)

1. Furman W.N., Nieto J.W., Batts W.M. Wideband HF channel availability – measurement techniques and results. 14th International Ionospheric Effects Symposium (Alexandria, Virginia. USA). 2015. http://ies2015.bc.edu.
2. Ivanov D.V., Ivanov V.A., Rjabova M.I., Bel'gibaev R.R., Ovchinnikov V.V., Chernjad'ev A.V. Razvitie metodov spektral'nogo monitoringa pomeh KV diapazona dlja opredelenija dostupnosti parcial'nyh ionosfernyh radiokanalov s uchetom osobennostej izmenchivogo spektra. Radiotehnika. 2023. T. 87. № 12. S. 64−77. DOI: https://doi.org/10.18127/j00338486-202312-08 (in Russian).
3. Md G. Mostafa, Haris Haralambous. Wideband Channel Availability Statistics over the High Frequency Spectrum in Cyprus. 2nd URSI AT-RASC (Gran Canaria, Spain). 2018. www.ursi.org.
4. Ivanov V.A., Ryabova N.V., Belgibaev R.R. Development of an algorithm for assessment of PSD of HF radio interference including analysis of daily and seasonal variations and their impact on channel availability. 2024 Systems of Signal Synchronization, Generating and Processing in Telecommunications (SYNCHROINFO). Vyborg. Russian Federation. 2024. Р. 1-4. DOI: 10.1109/SYNCHRO-INFO61835.2024.10617754.
5. Ivanov V.A., Rjabova N.V., Carev I.E. Diagnostika funkcii rassejanija dekametrovyh uzkopolosnyh stohasticheskih radiokanalov. Radiotehnika i jelektronika. 2010. T. 55. № 3. S. 285-291 (in Russian).
6. ITU-R Rec. F1487. Testing of HF Modems with Bandwidth of up to about 12 kHz Using Ionospheric Channel Simulator. Geneva: Int. Telecom. Union, 2000.
7. Watterson C., Juroshek J., Bensema W. Experimental Confirmation of an HF Channel Model. IEEE Transactions on Communication Technology. 1970. V. 18. № 6. P. 792-803. DOI: 10.1109/TCOM.1970.1090438.
8. CCIR Recommendation 520-1 19821. Use of high frequency ionospheric channel simulators. Geneva: Int. Telecom. Union, 1995.
9. Ivanov D.V. Metody i matematicheskie modeli issledovanija rasprostranenija v ionosfere slozhnyh dekametrovyh signalov i korrekcija ih dispersionnyh iskazhenij: monografija. Joshkar-Ola: MarGTU. 2006. 268 s. (in Russian).
10. Arthur P. C., Maundrell M. J. Multi-dimensional HF modem performance characterization. IEE 7th Int. Conf. on HF Radio Systems and Techniques. Conf. Publ. 1997. № 411. P.154–158.
11. Ivanov D.V., Ivanov V.A., Rjabova N.V., Bel'gibaev R.R., Chernjad'ev A.V. Monitoring spektra pomeh i dostupnosti KV-ra-diokanalov s polosami 3-24 kGc. Vestnik Povolzhskogo gosudarstvennogo tehnologicheskogo universiteta. Ser. Radiotehnicheskie i infokommunikacionnye sistemy. 2022. № 1(53). S. 21-32. DOI: https://doi.org/10.25686/2306-2819.2022.1.21 (in Russian).
12. Ivanov D.V., Ivanov V.A., Rjabova N.V., Bel'gibaev R.R. Ocenka dostupnosti chastotnyh kanalov dlja razlichnyh modemov KV-svjazi na osnove passivnogo zondirovanija mnogomernogo ionosfernogo radiokanala. Vestnik Povolzhskogo gosudarstvennogo tehnologiches-kogo universiteta. Ser. Radiotehnicheskie i infokommunikacionnye sistemy. 2017. № 2(34). S. 39-53. DOI: 10.15350/2306-2819.2017.2.39 (in Russian).
13. Harris T.J. Scholz M.L. Characterisation of narrowband HF channels in the mid and low latitude ionosphere. In Characterising the Ionosphere. Meeting Proceedings RTO-MP-IST-056, Neuilly-sur-Seine, France: RTO. 2006. Paper 17, pp. 17-1 – 17-14. Available from: http://www.rto.nato.int/abstracts.asp.
14. Ivanov D.V., IvanovV. A., Rjabova N.V. i dr. Aktivno-passivnyj radiosensor dlja povyshenija jeffektivnosti KV-svjazi. Jelektronika, fotonika i kiberfizicheskie sistemy. 2023. T. 3. № 1. S. 7-12 (in Russian).
15. Ivanov D.V., Ivanov V.A., Ryabova N.V., et al. Universal ionosonde for diagnostics of ionospheric HF radio channels and its application in estimation of channel availability. 12th European Conference on Antennas and Propagation (EuCAP 2018). London. 2018. P. 1-5.