Method and device for measuring phase noise using carrier removal

Abstract

The subject of the application is a method and device for measuring phase noise using carrier removal. The method of measuring phase noise using carrier removal according to the invention consists in taking a discrete Fourier transform (104) of N samples from the RAM memory (103), then determining the index L of the spectrum point with the highest amplitude, then the index L, the amplitude A(L) of the spectrum point with the index L, the phase ö(L) of the spectrum point with the index L, the amplitude A(L+1) of the upper side point with the index L+1 and the amplitude A(L-1) of the lower side point with the index L-1 are fed to the calculating circuit (107), in which the frequency of the input signal fm, its phase öm and the amplitude Am are calculated from these values ​​using the interpolated discrete Fourier transform method, the determined values ​​are used to initialize the digital generator (108), from which the signal is multiplied in the multiplier circuit (109) by samples read from the RAM memory (103),then the signal from the output of the multiplier (109) is low-pass filtered in the filter (110), and then the amplitude spectrum is determined from N samples of this signal using the second discrete Fourier transform (111), and for the values ​​being the second discrete Fourier transform (111), the results are compressed (112) and the obtained phase noise spectrum is displayed,