Развитие и верификация методов автоматической обработки спектра помех в КВ-диапазоне с применением технологии программно-конфигурируемых радиосистем в задаче оценки доступности радиоканалов
Authors: Иванов Д.В. , Иванов В.А. , Рябова Н.В. , Бельгибаев Р.Р. , Чернядьев А.В. 
Published: February 2025

Проблемой ионосферной КВ-радиосвязи является изменчивость диапазона рабочих частот и параметров радиоканалов. Поэтому по-прежнему актуальной является задача создания радиосенсоров на базе программно-определяемого радио для повышения эффективности связи в сложных условиях изменчивости параметров радиоканала и канальных сосредоточенных помех. В последнем случае мониторы реализуют анализ спектральной плотности помех и пороговым методом определяют доступные каналы (свободные от сосредоточенных помех). Известные методы определения доступных каналов наталкиваются на проблему значительной неравномерности спектра, что приводит к ошибкам в определении доступности. Для устранения данного противоречия в работе предложен метод медианной фильтрации измеренного спектра скользящим фильтром. Метод получил экспериментальную верификацию при анализе спектра помех в условиях города Йошкар-Олы.

Introduction. The advent of cognitive radio technology brings forth a series of challenges, with the foremost being the need to monitor radio wave propagation conditions and the availability of multiple radio channels through spectral analysis. Software-defined radio (SDR) technology has facilitated the creation of versatile devices capable of fulfilling various tasks, including radio channel diagnostics and communication. This necessitates the creation of methods and algorithms to estimate radio channel occupancy by processing received data on HF band noise levels, thus enabling the adaptation of digital HF communication systems based on sounding outcomes. The quality of HF radio communication is significantly influenced by the signal-to-noise ratio (SNR). There are two approaches to enhance this value: 1) increasing transmitter power and 2) seeking channels with the lowest noise levels (highest availability). To evaluate the availability of variable channels, the communication system integrates a mode for monitoring interference spectral density with a resolution no less than the bandwidth of these channels. The outcomes of availability monitoring enable the identification of interference-free channels using the threshold method [1-7]. Nonetheless, the noise spectrum within the HF band exhibits considerable non-uniformity, resulting in inaccuracies in determining radio channel availability. Consequently, the challenge of increasing data rates within the HF band under the umbrella of cognitive radio (CR) and SDR technologies compels the development of corresponding methods and algorithms. One facet of this endeavor involves crafting algorithms and software for interference spectrum monitoring within the HF band, coupled with a study of the statistical attributes of occupied channels. The aim of the work: Development of a method for assessing the availability of HF radio communication channels, considering the features of power spectral density (PSD) of interference. Conclusion. We have developed a method for assessing the availability of HF communication channels with a bandwidth of 3 to 48 kHz. The uniqueness of this method lies in its utilization of median PSD filtering with a small aperture of 3 samples. This filter effectively reduces fluctuations among the minimum spectrum values. The developed method has led to a noticeable increase in the average channel availability within the tactical communication frequency range, exhibiting a rise of 12–32% during the daytime and 1–17% during nighttime. Similarly, within the strategic communication frequency range, availability has increased by 9–25% during the daytime and 8–17% during nighttime. To experimentally verify this enhanced availability assessment method, we designed a software and hardware complex supported by SDR and CR technologies. The software enables spectral monitoring of interference levels within the HF band. Additionally, we have designed an active omnidirectional antenna with a uniform frequency response and developed a passive sensor, encompassing both hardware and software components, aimed at the collection and analysis of interference PSD within the HF band. This system enables automated assessment of channel availability for communication spanning the 3 to 48 kHz range. This methodology promises to enhance the efficacy of long-haul communication, particularly in challenging scenarios characterized by fluctuating radio channel attributes and narrowband interference.