A level measurement apparatus for measuring a distance to a material having a surface, said level measurement apparatus comprising: a transducer coupled to a transmitter for emitting energy pulses and further coupled to a receiver module for receiving energy pulses reflected by the surface of the material and generating an echo signal; the transmitter and receiver module being coupled to a controller which operates under stored program control, said stored program including a receive signal processing module; said combined receiver module and receive signal processing module including means for low pass filtering and envelope detection of the receive echo signals, said receiver module including an analog-to-digital converter; and said receive signal processing module including a processing component for calculating the distance to the surface of material based on the low pass filtered and envelope detected digitized echo signal, characterized in that the receive signal processing module includes, between the analog-to-digital converter and the processing component: a program component configured to buffer digital samples from the analog-to-digital converter in a memory accessible by said controller; a digital low pass filter program component configured to low pass filter a plurality of said buffered digital samples; a bandpass filtering program component configured to band pass filter a plurality of said low pass filtered digital samples, said transducer having an operating frequency and said band pass filter having a center frequency corresponding to said operating frequency; a digital envelope detection program component configured to detect positive peaks in said band pass filtered digital samples; and a data compression program component configured to convert the digital samples in said envelope to compressed digital samples. a transducer coupled to a transmitter for emitting energy pulses and further coupled to a receiver module for receiving energy pulses reflected by the surface of the material and generating an echo signal; the transmitter and receiver module being coupled to a controller which operates under stored program control, said stored program including a receive signal processing module; said combined receiver module and receive signal processing module including means for low pass filtering and envelope detection of the receive echo signals, said receiver module including an analog-to-digital converter; and that the receive signal processing module includes, between the analog-to-digital converter and the processing component: a program component configured to buffer digital samples from the analog-to-digital converter in a memory accessible by said controller; a digital low pass filter program component configured to low pass filter a plurality of said buffered digital samples; a bandpass filtering program component configured to band pass filter a plurality of said low pass filtered digital samples, said transducer having an operating frequency and said band pass filter having a center frequency corresponding to said operating frequency; a digital envelope detection program component configured to detect positive peaks in said band pass filtered digital samples; and a data compression program component configured to convert the digital samples in said envelope to compressed digital samples. a program component configured to buffer digital samples from the analog-to-digital converter in a memory accessible by said controller; a digital low pass filter program component configured to low pass filter a plurality of said buffered digital samples; a bandpass filtering program component configured to band pass filter a plurality of said low pass filtered digital samples, said transducer having an operating frequency and said band pass filter having a center frequency corresponding to said operating frequency; a digital envelope detection program component configured to detect positive peaks in said band pass filtered digital samples; and a data compression program component configured to convert the digital samples in said envelope to compressed digital samples.