Figure 6b. (a) Schematic of a pulsed-wave Doppler instrument. A single transducer is used in pulse-echo mode. The other boxes indicate the flow of data through the instrument and the stages of Doppler shift processing for pulsed-wave US. (b) Image display from pulsed-wave Doppler US. Red line indicates the axial line used to interrogate a volume contained within the range gate. The angle correction is also indicated.