| 摘要 |
<p>A system suitable for reducing static or slow moving echoes from acoustic boundaries in a system such as pipe walls, blood vessels, tissue structures is disclosed so that an image from flowing or time varying media such as water, oil, blood etc may be imaged more clearly. The system 20 comprises an analogue-to-digital converter 21 for digitizing a received analogue signal from a detector; means 22 for digitally separating static or slow moving components of the digital signal; a digital-to-analogue converter 23 to provide an analogue version of the separated static or slow moving components of the signal and a subtractor 24 to subtract the analogue version of the static or the slow moving components of the signal from an analogue signal received from a detector to produce an analogue signal corresponding to the remaining flow components of the signal. Examples of the system described above produce an image corresponding to the flowing media with a higher signal to noise ratio providing higher resolution images.</p> |
