Fill level measurement device

A method of time-of-flight signal processing, comprising:

• generating a time-of-flight measurement signal;
• transmitting the measurement signal to a surface that will at least partially reflect the measurement signal;
• receiving the reflected measurement signal;
• mixing the received measurement signal with a generated local oscillator signal to yield an analog intermediate frequency signal;
• filtering the analog intermediate frequency signal via a broadband band-pass filter, wherein the broadband band-pass filter is embodied to pass the analog intermediate frequency signal and to filter out unwanted harmonics;
• amplifying the analog intermediate frequency signal to increase the signal strength of the filtered analog intermediate frequency signal;
• selecting a sampling frequency wherein the sampling frequency is less than a center frequency of the analog intermediate frequency signal, whereby Nyquist zones are defined by the sampling frequency;
• filtering the analog intermediate frequency signal to reduce signal components not in a third Nyquist zone;
• sampling at the sampling frequency the analog intermediate frequency signal via an analog-to-digital converter to produce a digital intermediate frequency signal;
• analyzing the digital intermediate frequency signal to produce an envelope curve;
• and
• determining a time-of-flight from the envelope curve.