Procedure for the measurement of a level (L) of a medium located in a vessel , wherein the following occurs in consecutive measurement cycles, - signal pulses of a predefined frequency (f s ) are emitted into the vessel using a transmission and reception unit at a predefined repetition frequency (f r ), and their signal parts (R) reflected in the vessel in the direction of the transmission and reception unit are received as a reception signal (E) after a transit time (t) that depends on the distance traveled, - on the basis of the reception signal (E), an auxiliary signal (ZF, ZA) is derived over a predefined transit time range, said auxiliary signal providing amplitude and phase information of the reception signal (E), which is contained in the reception signal (E), as a function of the associated transit time (t), - a transit time (t) of a signal part that is reflected at a medium surface is determined as a base transit time (t G ) on the basis of the auxiliary signal, - transit times (t i ) of zero crossings of the auxiliary signal (ZF, H) are determined, - on the basis of the transit times (t i ) of the zero crossings of the auxiliary signals (ZF, ZA) determined in the current measurement cycle and in several previous measurement cycles, a phase frequency distribution (N(t)) is derived as a function of the transit time (t), said distribution indicating the frequencies at which zero crossings were present in the associated auxiliary signals (ZF, H) at the respective transit times (t), - a transit time (t NV ) of a maximum (NV max ) of the frequency distribution (N(t)), which is closest to the base transit time (t G ), is determined as the level transit time (t L ), and - the level (L) is determined on the basis of a propagation speed of the signal pulses, an installation height (H 0 ) of the transmission and reception unit above the vessel and the level transit time (t L ). - signal pulses of a predefined frequency (f s ) are emitted into the vessel using a transmission and reception unit at a predefined repetition frequency (f r ), and their signal parts (R) reflected in the vessel in the direction of the transmission and reception unit are received as a reception signal (E) after a transit time (t) that depends on the distance traveled, - on the basis of the reception signal (E), an auxiliary signal (ZF, ZA) is derived over a predefined transit time range, said auxiliary signal providing amplitude and phase information of the reception signal (E), which is contained in the reception signal (E), as a function of the associated transit time (t), - a transit time (t) of a signal part that is reflected at a medium surface is determined as a base transit time (t G ) on the basis of the auxiliary signal, - transit times (t i ) of zero crossings of the auxiliary signal (ZF, H) are determined, - on the basis of the transit times (t i ) of the zero crossings of the auxiliary signals (ZF, ZA) determined in the current measurement cycle and in several previous measurement cycles, a phase frequency distribution (N(t)) is derived as a function of the transit time (t), said distribution indicating the frequencies at which zero crossings were present in the associated auxiliary signals (ZF, H) at the respective transit times (t), - a transit time (t NV ) of a maximum (NV max ) of the frequency distribution (N(t)), which is closest to the base transit time (t G ), is determined as the level transit time (t L ), and - the level (L) is determined on the basis of a propagation speed of the signal pulses, an installation height (H 0 ) of the transmission and reception unit above the vessel and the level transit time (t L ). <EOS>