Method and device for optimising the measuring time for noise or spectrum analysers using cross correlation methods

摘要

To measure the power density spectrum of an input signal, Fourier transformation signals are formed in two paths. A number of averages are used for cross correlation of the two signals. A value (Metrik L) is computed from the two signals and the averages as the exit point criterion for further averaging. The computing unit (33) takes the two signal values ((y1(k),y2(k)) to give their squares (20,21) to be given mean values (22,23). The signals are also multiplied (26) to be given a mean value (27). A divider (25) is linked to a multiplier (29) with the number (N) of averages to give the value.