ultra broadband signals
V.I. Shchetinin, Yu.A. Kavin, L.S. Pritchina
Simulation modeling is quite an asked-for component in scientific research, especially in the cases, when the subject of inquiry is influenced by a great number of various chance factors. Among software products which make possible to carry out computer-generated simulation experiment, MATLAB controlled SIMULINK software package should be mentioned.
Herein a SIMULINK simulation model flowchart, which illustrates forming and processing ultra broadband (UBB) signals of several varieties, has been developed. Particularly, one of the UBB signals under consideration is a frequency-shift keyed (FSK) group signal, synthesized on the base of the singular ensemble of optimum discrete patterns with the «no more than one coincidence» fundamental property. Each of the singular ensemble components presented an independent signal of its carrier frequency. Meanwhile the law of carrier-frequency variation from signal to signal in the ensemble is the linear ladder one. A frequency-phase-shift keyed (FPSK) signal with through additional phase-shift keying and pseudo-random frequency keying of ensemble components is being considered as an alternative. Two more intermediate varieties of signal have been considered. Side lobes volume unit level, as well as the first side lobe maximum peak level, was regarded as the quality rating of the examined radio signals.
Peculiarities of detection – resolution problems of the signals have also been examined, the latter being reflected by a multiple target under different ratios of signal amplitudes and different noise intensity. The filtration in the frequency domain has been applied when carrying out processing chain within the built simulation model. The results of the model functioning were statistically averaged. Among the conclusions that can be drawn on the basis of the obtained results analysis one should mention the following: to provide for the proper detection probability P = 0,9 and simultaneous resolution of two FPSK signals of the same intensity it is needed to increase the signal-noise ratio by 0,5 dB; that is negligible compared with detection – resolution of two FSK signals. However the application of FPSK signals, synthesized on the base of the ensemble of optimum discrete patterns, is more reasonable in comparison with FSK ones, so far as additional phase and pseudo-chaotic frequency manipulation of the ensemble components enables to reduce essentially the side-lobe level of time frequency frustration function and approximate it to the ideal acicular one.