An ultrasonic imaging apparatus having a depth range setter 28 for setting a threshold value of detection level for a Doppler signal in an ultrasonic circuit unit 2, a unit for extracting a time at which the Doppler signal exceeds the set detection level and a signal level in excess of the set detection...http://www.google.se/patents/US6677985?utm_source=gb-gplus-sharePatent US6677985 - Ultrasonic video apparatus
