| 摘要 |
The apparatus for examining an object by means of ultrasound has an emitting transducer and a receiving transducer with a plurality of transducer elements. Electrical signals from the receiving transducer elements are selectively connected to input taps of a single delay line for individually delaying the electrical signals to compensate for their different distances from points under investigation in the object. For each point in the object a first received echo signal is connected to a first input tap giving a first delay, and subsequently received echo signals are connected to input taps being selected so that the subsequent electrical signals are output on the output tap substantially simultaneously with the electrical signal representing said first received echo. The receiving transducer is thereby adjusted currently during the reception of each scan line to perfectly adapt its focus at each instant in time and with an exceptionally high degree of accuracy. Additionally, switching noise in the switching network at the input of the delay line is canceled by first recording a scan line without signal from the emitting transducer as reference signals and subtracting these scan line reference signals from subsequent ultrasound echo signals.
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