Video imaging using multi-ping sonar

Abstract

A sonar system comprising a sonar transmitter, a very large array two dimensional sonar receiver, and a beamformer section transmits a series of sonar pings into an insonified volume of fluid at a rate greater than 5 pings per second, receives sonar signals reflected and scattered from objects in the insonified volume, and beamforms the reflected signals to provide a video presentation and/or to store the beamformed data for later use. The parameters controlling the sonar system are changed between pings to provide enhanced video imaging.

1 . A method of recording a 3D sonar image, comprising;
 a) transmitting a series of sonar pings into a first volume of water, the series of sonar pings transmitted from a sonar ping transmitting device at a rate at least 5 pings per second, wherein the sonar ping transmitting device is controlled by sonar ping transmitting parameters, and wherein each sonar ping transmitting parameter is chosen from predetermined list of sonar transmitting parameter settings;   b) receiving sonar signals reflected or scattered from objects in the first volume of water from each of the series of sonar pings, the received sonar signals received by a large two dimensional array sonar receiving device;   c) wherein the sonar receiving device is controlled by sonar receiving parameters, and;   d) beamforming the received sonar signals from each of the series of sonar pings with a sonar beamforming device to form a three dimensional (3D) sonar image of the objects reflecting or scattering the received sonar signals, wherein the sonar beamforming device is controlled by a set of sonar beamforming parameters, and wherein each sonar beamforming device parameter is chosen from predetermined list of sonar beamforming device parameter settings;   e) wherein at least one of the sonar transmitting parameters; sonar receiving parameters, or sonar beamforming parameters is changed in the time between any two sonar pings of the series of sonar pings.   
     
     
         2 . The method of  claim 1 , wherein the transmitter frequency is changed in the time between any two sonar pings of the series of sonar pings. 
     
     
         3 . The method of  claim 2 , wherein the transmitter frequency is changed from a first frequency to a second frequency and back between each ping of the series of sonar pings. 
     
     
         4 . The method of  claim 3 , wherein a sonar beamforming device parameter wherein each is changed between each ping of the series of sonar pings. 
     
     
         5 . The method of  claim 2 , wherein the transmitter frequency and the insonified volume are changed in the time between any two sonar pings of the series of sonar pings. 
     
     
         6 . The method of  claim 1 , wherein at least one sonar beamforming parameters is changed in the time between any two sonar pings of the series of sonar pings. 
     
     
         7 . The method of  claim 6 , wherein at least two different fields of view are imaged in the series of sonar pings. 
     
     
         8 . The method of  claim 7 , wherein at least four different fields of view are imaged in sequence in the series of sonar pings, and wherein images of the four different fields of view are stitched to make one composite image, and wherein the a series of composite images is presented as a video presentation with a frame rate of at least 5 frames per second. 
     
     
         9 . A method of real time three dimensional (3D) sonar imaging, comprising:
 a) insonifying a first volume of fluid with a first series of at least one sonar ping transmitted by a first sonar transmitter; wherein the first sonar transmitter frequency has a first sonar transmitter frequency parameter set to a first sonar frequency, then   b) changing the first sonar transmitter frequency parameter to a second sonar frequency, then   c) transmitting a second series of at least one sonar ping, wherein the time between the last sonar ping of the first series of sonar pings and the first sonar ping of the second series is less than 0.2 seconds, and wherein the first series of sonar pings and the second series of sonar pings are transmitted at a rate greater than 5 pings a second;   d) receiving for each of the series of sonar pings sonar signals reflected from one or more objects in the volume of fluid, wherein the sonar signals are received with a large 2D array of sonar signal detectors;   e) beamforming the reflected sonar signals for each of the series of sonar pings to provide a series of three dimensional (3D) sonar images of the one or more objects.   
     
     
         10 . The method of  claim 9 , further comprising;
 f) recording a video presentation of the series of 3D sonar images shown sequentially at a rate greater than 5 images per second.   
     
     
         11 . The method of  claim 9 , further comprising;
 f) producing a series of sonar images by alternating the first sonar transmitter frequency parameter between the first and the second sonar frequencies ping to ping; then   g) stitching neighboring pairs sonar images of the series of 3D images provided in step e) to make a third series of composite sonar images having a wider field of view than images in the first series and a resolution over portions of the field of view higher than images in the second series; then   h) recording a video presentation of the composite 3D sonar images shown sequentially at a rate greater than 5 images per second.   
     
     
         12 : The method of  claim 5 , wherein resulting images alternate between a higher resolution and smaller field of view for the higher frequency and a lower resolution and larger field of view for the lower frequency, and the alternating images are stitched after the receiver stage to provide video stream with a higher central resolution and wider field of view at half the frame rate of the system available with unchanged parameters. 
     
     
         13 . The method of  claim 5 , where resulting images alternate between a higher resolution and smaller field of view for the higher frequency and a lower resolution and larger field of view for the lower frequency, and the alternating images are stitched as neighboring images to provide a video stream at the same frame rate but a larger field of view. 
     
     
         14 . The method of  claim 8 , wherein only a subset of the at least four images is updated continuously to generate real time images. 
     
     
         15 . The method in  claim 8 , wherein at least one low frequency, low resolution ping with a large field of view is used to locate a target of interest, and subsequent high frequency high resolution pings are directed at a region of interest without steering the sonar head. 
     
     
         16 . The method of  claim 8 , wherein intelligent processing is used to account for and/or track motion of moving objects. 
     
     
         17 . The method of  claim 8 , wherein predictive processing is used to account for and/or track motion of moving objects. 
     
     
         18 . The method of  claim 8 , wherein interframe alignment is used to account for and/or track motion of moving objects. 
     
     
         19 . The method of  claim 8 , wherein the portion of the field of view containing the motion of moving objects is updated more frequently than the remaining portions of the field of view.