| 摘要 |
PURPOSE:To compress and demodulate a plurality of ultrasonic signals fed in parallel on the frequency axis by converting analog signals into digital, demodulating into the band centering on DC by the use of the first to third complex digital reference signal groups, and emitting a complex signal of single band by a phasing circuit using a low pass filter. CONSTITUTION:Input ultrasonic received signal groups 1000,... are fed to multipliers 1020,... via analog-digital converters 1010,.... They are multiplied by three sorts of signals and forwarded to complex multipliers 1040,... upon passing through low pass filters 1030,.... The result from multiplication by complex number using three sorts of signals is passed through adders 1050, 1051 and stored in memory means 1060, 1061. The output read out of it is subjected to multiplication by complex number in complex multipliers 1070,..., passed through low pass filters 1080,..., and converted finally into an image signal by a signal processing circuit. |
