A fluid flow meter system for monitoring fluid flow through a lumen includes a first ultrasonic transducer configured to transmit one or more versions of a transmit (TX) signal through a fluid flowing within the lumen, and a second ultrasonic transducer configured to receive one or more respective receive (RX) signals. The fluid flow meter system includes an analog-to-digital converter (ADC) configured to sample, at a first frequency, the one or more RX ultrasonic signals and a processor configured to generate a fine resolution signal based on the one or more RX ultrasonic signals. The fine resolution signal is associated with a second sampling rate higher than the first sampling rate. The processor is also configured to compute a cross-correlation signal indicative of cross-correlation between the fine resolution signal and a waveform and determine an estimated fluid flow parameter based on the computed cross-correlation signal.