An optimal adaptive S-transform time-frequency space model for electromagnetic interference complexity evaluation

The issue of significant amplitude shifting with frequency in the evaluation of electromagnetic interference complexity using the S-transform can result in inaccurate extraction of energy occupancy evaluation parameters. This paper proposes a method of electromagnetic environment complexity evaluation based on the optimal adaptive S-transform (OAST) time-frequency space model. Firstly, the flexible adjustment of the window width of the S-transform window function is achieved by introducing adaptive parameters, so as to suppress the large migration of the amplitude characteristics with the signal frequency. Then, the calculation formulae for the evaluation parameters of time occupation, frequency occupation and energy occupation based on OAST are derived, and the OAST time-frequency spatial evaluation model is established; Finally, the qualitative and quantitative evaluation criteria of subjective and objective complexity based on the OAST time-frequency spatial model are analyzed and determined, overcoming the limitations of the independent grading of the traditional electromagnetic interference complexity evaluation parameters. Simulation and experimental results show that OAST can accurately extract the time-frequency energy occupation parameters and the feature parameters in the time-frequency domain are more accurate; the OAST time-frequency spatial model can evaluate the signal complexity level more accurately, and the evaluation experiments verify the correctness of the proposed method.