Abstract: The invention relates to a method for determining the signal-to-noise ratio (20) of a target echo (11) from a received signal (UE) received from an ultrasonic sensor (3) of a motor vehicle (1), in which: a transmission signal is transmitted in encoded form, the received signal (UE) is decoded and decoding involves the received signal (UE) being correlated with a reference signal and the correlation provides a correlation signal (UK), and the target echo (11) is detected in the correlation signal (UK), wherein the signal-to-noise ratio (20) is determined by determining a value (21) of the noise in the received signal (UE) on the basis of the correlation signal (UK) and, in so doing, dividing the correlation signal (UK) into a multiplicity of signal segments (17a to 17e) and determining the value (21) of the noise solely on the basis of signal values for that one of the signal segments (17a to 17e) that contains the target echo (11).