Algorithm for preliminary identification of radio signals with spectral masks
Purpose. The implementation of broadband radio monitoring involves determining the belonging of observed radio emissions to specific data transmission standards. The procedures for full-scale verification of such an affiliation are very laborious, so it is advisable to use a two-stage identification procedure, at the initial stage of which the most plausible are identified among possible hypotheses about compliance of radiation with standards, and at the final stage, after a detailed recheck of these hypotheses, final decisions are made. The purpose of the work is to develop an algorithm for preliminary identification of signals, which allows us to hypothesize that the observed radio emissions belong to different standards only on the basis of broadband spectral diagrams accumulated over a wide range of samples. The formation of accumulated spectral diagrams is an integral part of the procedure for detecting radio emissions and therefore their use does not increase the computational complexity of signal processing in radio monitoring systems. Novelty. The proposed identification algorithm takes into account the possibility of significant deformation of the accumulated signal spectra due to interference distortions and uses the combination of known statistics (modified correlation coefficient of fragments of accumulated spectral diagrams with spectral masks of detected emissions) and author's approaches to search for target signals. The latter include control of compliance of stretching degree of the normalized reference spectra (spectral masks) with physical expectations, estimation of mismatch between the spectra of the received signal and spectral masks, as well as specialized check of integrity of the identified spectra. Results. The practical testing of the proposed algorithm on real signals demonstrates the stability of its operation and the high reliability of identifying signals even with significant interference distortions of their spectra in a complex urban radio setting. Comparative testing shows that the proposed algorithm is operational at a signal-to-noise ratio 5-10 dB less than the values required for other known algorithms presented in the technical literature. Practical relevance: the implementation of the developed algorithm provides radio monitoring systems with a reduction in the cost of time and computing resources to determine the belonging of detected signals to specific data transmission standards.