G. N. Prokhladin

The method of modelling of target spectral characteristics of synthesizers of frequencies on the basis of pulse-phase-lock loop (PPLL) is presented. The analysis of the received spectral characteristics is carried out at change of parameters: factors of strengthening of system, constants of integration of the filter of the bottom frequencies, factors of division of dividers, frequency of comparison, a system pass-band. Comparison of spectral characteristics with various types of basic and operated generators is resulted. The possible reasons of deterioration of quality indicators of target spectral characteristics of PPLL are found out. Directions of improvement of quality of the given characteristics are shown. So pass-band decrease at the big factors of multiplication of system can lead to undesirable liftings in the target spectrum, caused by small strengthening of the opened loop and insufficient suppressiof deterioration of quality indicators of target spectral characteristics on of noise of the operated generator. In this case the problem decision probably at use of the operated generator with more sound planimetric structure. The spectral analysis was spent in software Mathcad.