| 摘要 |
PROBLEM TO BE SOLVED: To perform a qudrature modulation even in a synthetic aperture sensor, by a method wherein the phase of a transmission signal in the start of a transmitting operation is made to agree with the phase of a qudrature carrier signal, which is used for the qudrature modulation of a reception signal. SOLUTION: A transmission synchronization circuit 13 in a synchronous qudrature modulation part 1 synchronizes a transmission start signal in a system control part 2 with a phase signal in a qudrature carrier-signal generation circuit 11 so as to generate a transmission start pulse signal. A transmission signal in a transmission-signal generation part 3 is inputted to a transmission part 4, and the echoed sound of its transmission sound is received by a reception part 5. A qudrature modulation computing circuit 12 to which its reception signal is inputted qudrature-modulates the reception signal by using the qudrature carrier signal in the qudrature carrier-signal generation circuit 11, and the signal is converted into a qudrature baseband signal so as to be then outputted to an A/D conversion part 6. At this time, the transmission synchronization circuit 13 synchronizes the signal so as to generate the transmission start pulse signal. As a result, the phase of the transmission signal in the start of a transmitting operation agrees with the phase of the qudrature carrier signal. Consequently, also a system which uses information on the phase of a certain target signal obtained by a plurality of transmitting operations can fetch a qudrature modulation. |
