| 摘要 |
<p>A scanner includes a scan head having a linear array of transducers Xn, and a transmitter 106 which excites the transducers in response to transmit signals TRn from a reference generator 110 so that the transducers emit a plurality of successive bursts of ultrasonic energy, each burst producing a transmitted beam which is steered and focused along a radially-extending scan line. To effect received beam steering and focusing, received signals Sn from the transducers are supplied to a processor 112 along with associated in-phase binary reference signals bn(R) and quadrature binary reference signals bn(I). The received signal is multiplied by a reference signal and the product is integrated for a specific time duration whose time occurrence is used to steer and focus the beam. Processor 112 is responsive to WRITE SELECT, READ SELECT and SAMPLE signals from reference generator 110 to correlate each signal Sn with its associated reference signals during a plurality of successive resolution windows, each of which corresponds to a distinct incremental area along a scan line, so as to provide in-phase and quadrature output signals Re and Im each representing a response of the array to reflections from successive incremental areas along a scan line. Signals Re and Im are combined by processors 114 and 116 to develop output signals A and O representing, respectively, the amplitude and phase of returns from successive incremental areas along a scan line. Information for transmitted and received beam steering and focusing is stored in a phase pattern memory 118A, and extracted therefrom by a controller 118 in a predetermined order and supplied to reference generator 110.</p> |
