Patent ID: 7460433

Claim:
An ultrasonic transmitting and receiving system comprising: a sonar apparatus equipped on a ship and detecting underwater objects by a transmission beam formed with a detection signal and at least a reception beam formed with echo signals; and a transponder in water, the transponder transmitting a response signal having a frequency band different from a frequency band of the detection signal in response to an activation signal transmitted from the sonar apparatus and received thereby, the activation signal having a frequency band different from the frequency band of the detection signal; and wherein the sonar apparatus includes: a transmission beam former for transmitting the detection signal in a form of transmission beam, the transmission beam former having sections for separately forming the transmission beam of the detection signal to a detection range and a transmission beam of the activation signal to the transponder, a reception beam former for receiving an echo signal produced by an object reflecting the detection signal and the response signal, and an indicator for displaying the echo signal and the response signal; and wherein the transmission beam former forms the transmission beam of the activation signal to the transponder according to an azimuth from the sonar to the transponder or a tilt angle.