| 摘要 |
PURPOSE:To make the constitution of a mixing element simple, moderate a requirement also pertaining to the frequency characteristic of a main delay element and also make the constitution of this portion simple by making the process to mix with a reference signal of the same phase after respective operations for little delays. CONSTITUTION:Transmitting signals are applied from a circuit for transmission to a part of elements TRN and ultrasonic pulses are transmitted to a target. The reflected acoustic waves generated by this are detected in respective elements TRN. Several received signals are respectively mixed with a common reference signal from a reference signal generator RG in a mixing element M after receiving respectively delays in a little delay circuit SD. Low-frequency components generated by mixing receive the specific phase shifts respectively in a phase shifter PS, thereafter, receive delays respectively in a quantize delay circuit MD, and become the received signals omegan(t) added and phased by an adder AD. Thus, the constitution of the circuit MD becomes simple. The constitution of the mixing element M also becomes sharply simple because the reference signal is common to all signals. |
