Sonar method for detecting and/or determining the position and/or speed of objects underwater in a specified region, sonar assembly, and receiving unit

A sonar method for detecting and/or determining the position and/or speed of objects underwater and/or on the water in a specified region, comprising:

• rigidly installing and fixing a sonar transmitting device at a defined position in the specified region which can transmit a plurality of acoustic signals from sound generators that are distributed in a defined manner;
• providing a sonar receiving unit in the specified region and which sonar receiving unit comprises a passive receiver with a hydrophone;
• generating and transmitting orthogonal signals or orthogonal pings by spreading and/or compressing a selected signal sequence or a selected base signal by means of the sonar transmitting device;
• receiving and detecting the signal resulting from the reflection of the transmitted signal or ping on one or more objects by means of an individual hydrophone of the sonar receiving unit;
• and
• determining on the basis of the received and detected signal
• the presence or existence of an object and/or
• the directions from which the reflected signals originate and/or
• the position of all reflecting objects and/or
• the radial speed components of said objects with respect to the transmitter position
• wherein the determination is carried out using a ring buffer and a database with known and/or predeterminable digital correlators or matched filters,
• wherein the correlators are selected to identify the signal sequence or the base signal and its orthogonal signals compressed and stretched by the transmitter or orthogonal pings, and
• wherein the angle of the object is determined for a known time period and speed by adapting the original transmission signals to the Doppler shift using classic MIMO beamforming.