| 摘要 |
PURPOSE:To enhance distance resolution and bearing resolution by arranging a transmitting system and a receiving system in a rotary switching type thus switching the systems from one to the other at high speed, and performing frequency modulation based on Doppler effect caused by rotation, while performing reception using a matching filter for transmission and reception of frequency-modulated waves. CONSTITUTION:In an ultrasonographic device, a trigger pulse is guided to an FM signal generator waveform circuit and to a rotary scanning signal generator 24 from a synchronous signal generator 20, and a transmitted FM signal which is frequency-modulated by the FM signal generator waveform circuit 22 is fed to a wave transducer 26 via a switching circuit 28. The rotary scanning signal generator 24 controls the switching of delay tap during reception of input waves, recognizes the switching of the switching circuit 28, and then causes one or plural transmitting-receiving elements to equivalently rotate one by one at an angular velocity of (w) in e.g. the clockwise direction to selectively receive a signal for each element, from the finishing point of transmission to the start of reception, and the signals are fed to a compression filter 30; i.e., the input signals can be subjected to frequency modulation during reception. |
