Anti-collision sonar system

• US 3,886,487 A
• Filed: 05/31/1973
• Issued: 05/27/1975
• Est. Priority Date: 05/31/1973
• Status: Expired due to Term

• Current Assignee: George M. Walsh, James W. Cummings, Peter J. Clifford, William R. Backman Jr
• Original Assignee: George M. Walsh, James W. Cummings, Peter J. Clifford, William R. Backman Jr
• Inventors: Walsh, George M., Backman, William R. Jr., Clifford, Peter J., Cummings, James W.
• Primary Examiner(s): Farley, Richard A.
• Application Number:
  US05/365,819
• Time in Patent Office: 726 Days
• Field of Search: 340/1R,3D,3F,3R 343/1CL,5DP,9,112CA
• US Class Current: 367/92
• CPC Class Codes: G01S 15/60 wherein the transmitter and receiver are mounted on the moving object, e.g. for determining ground speed, drift angle, ground track
• CPC Class Codes: G01S 15/87 Combinations of sonar systems
• CPC Class Codes: G01S 15/93 for anti-collision purposes
• CPC Class Codes: Y10S 367/902 Speed of sound compensation
• CPC Class Codes: Y10S 367/905 Side lobe reduction or shading
• CPC Class Codes: Y10S 367/909 Collision avoidance

Abstract

A sonar system particularly adapted for navigating a ship in shallow waters employing a forwardly directed narrow sonar beam emanating from a projector assembly carried by the ship. The projector assembly is suitably positioned between the upper surface and lower surface of a body of water so that there is substantially no reverberation from waves at the upper surface and irregularities along the bottom for sufficient distances forward of the ship to present a clear view within the body of water. In one embodiment, the narrow beam is provided by a nonlinear finite amplitude interaction of two beams of sonic energy of relatively high frequency to provide a low frequency highly directive beam. In a second embodiment, a second sonar which measures depth and doppler quantities is coupled together with the forward looking sonar to provide a space stabilized display of data obtained with the forward looking sonar.

Claims

1. A sonar system comprising:

a transducer system;

means for positioning said transducer system between two boundaries of a layer of fluid, said transducer system including means for adapting said transducer system to produce a beam of radiant energy wherein the sides of the beam are substantially parallel to said boundaries, said positioning means including means for rotating a beam of energy emanating from said transducer system for directing said beam of radiation between said boundaries; and

means responsive to a speed of movement of said transducer system through said fluid for storing data obtained through the reception of radiant energy by said transducer system.

2. A system according to claim 1 wherein said storing means includes means for correlating signals received by said transducer system with a reference.

3. A system according to claim 2 wherein said transducer system includes means coupled to said correlating means for generating said reference and signals to be transmitted by said transducer system.

4. A system according to claim 3 wherein said generating means includes means for generating a signal at a first carrier frequency and a signal at a second carrier frequency.

5. A system according to claim 4 wherein said transducer system converts electrical signals into signals of sonic energy, said transducer system including means for radiating energy at said first carrier frequency and radiating energy at said second carrier frequency into a common region of said fluid layer for inducing a nonlinear interaction therein between sonic energy at said first carrier frequency and sonic energy at said second carrier frequency to provide within said beam a sonic energy at a frequency different from said first frequency and said second frequency.

6. A system according to claim 5 wherein said storing means includes a graphical recorder, said sonar system is transported by a ship driven by a rotating propeller, and said graphical recorder is coupled to said rotating propellor for advancing a recording medium at a speed proportional to a speed of movement of said ship.

7. A display system comprising:

first means for providing echo ranging signals in a first direction;

second means for providing echo ranging signals in a second direction having a component parallel to said first direction and a component perpendicular to said first direction;

means coupled to said second means for extracting doppler data from echo ranging signals of said second means;

means coupled to said first means for storing data obtained from echo ranging signals of said first means, said Storing means including means coupled to said doppler extracting means for repositioning data stored within said data storing means, said repositioning providing a correspondence between a position of said first means relative to a source of echoes of said echo ranging signal; and

means coupled sequentially to portions of said storing means for portraying said stored data.

8. A system according to claim 7 wherein said data storing means comprises bins for the storing of data, any one of said bins storing data of echoes emanating from sources of echoes located within a region spaced a predetermined distance from said first means, said system comprising means coupled to said doppler extracting means for weighting data stored in each of said bins in accordance with the magnitude of the doppler frequency of said doppler data.

9. A system according to claim 8 wherein each bin overlaps a portion of the next bin for storing data emanating from sources of echoes spaced in correspondingly overlapping distances from said first means.

10. A system according to claim 9 wherein said data storing means comprises a plurality of accumulating means for simultaneously accumulating data arriving simultaneously in a pair of bins.

11. A system according to claim 10 further comprising means coupled to said second means for measuring the time elapsed between a transmission and a reception of an echo of said echo ranging signal of said second means, means coupled to said elapsed time measuring means for storing successive values of said elapsed time, means coupled to said doppler extracting means and to said elapsed time storing means for entering values of said elapsed time into said elapsed time storing means at a rate proportional to the value of said doppler frequency, and means coupled to said elapsed time storing means for computing a distance at which the elapsed time of a future one of said echoes will have a predetermined value.

12. A system according to claim 11 wherein said weighting means comprises means for providing a sequence of pulses having a predetermined number of said pulses for individual ones of echoes received by said first means of its echo ranging signal.

13. A system according to claim 12 wherein said data storing means comprises means for sequentially coupling data of said bins to said portraying means.

14. A system according to claim 13 wherein said sequential coupling means comprises memory means for periodically gathering data of said bins, said memory means being coupled to said portraying means to permit said gathered data to be displayed at a rate independent of a rate of entry of data into said bins.

15. A system according to claim 14 further comprising means coupled to said first means for counting successive echoes of said echo ranging signal of said first means, means for addressing said memory means, and means coupled to said counting means and said memory addressing means for triggering said portraying means to portray data of said memory means.

16. A correlation system comprising:

means for transmitting ranging signals, said transmitting means including means for modulating said ranging signals;

means for receiving reflections of said ranging signals;

means coupled to said transmitting means and to said receiving means for correlating modulation of received reflections with the modulation of said transmitted ranging signals; and

means synchronized with said transmissions of said ranging signals and coupled to said correlating means for summing together a sequence of output signals of said correlating means wherein successive signals of said sequence correspond to successive transmissions of said ranging signals.

17. A system according to claim 16 wherein said summing means is responsive to a speed of movement of said transmitting means for summing an output signal of said correlator occurring at a shifted interval of time, the amount of said shifted interval of time being proportional to said speed of movement.

18. A system for navigating a vehicle traveling through a medium, said system comprising:

means for measuring the distance between said vehicle and a boundary of said medium;

a memory for storing values of distance;

means for reading out from said measuring means and into said memory, at a rate proportional to a speed of travel of said vehicle, values of distance measured by said measuring means; and

means coupled to said memory for computing an average slope of said boundary from said stored distance measurements to provide the range to an intersection of a path of travel of said vehicle with an extension of a boundary line having said average slope.

19. A system according to claim 18 further comprising means for measuring said speed of travel, said speed measuring means being coupled to said reading means to provide said reading rate proportional to said speed of travel.

20. A system for navigating a vehicle through a medium, said system comprising:

means for measuring range from said vehicle to objects submerged in said medium, said measuring means including means for illuminating said objects with a beam of radiant energy, said measuring means providing range measurements of objects positioned relative to said vehicle so as to be illuminated by said beam;

means coupled to said range measuring means for displaying a summation of successive ones of said range measurements for each of said objects, a value of an individual one of said summations for an individual one of said objects being retained when said illumination by said beam terminates; and

means for measuring a speed of travel of said vehicle, said speed measuring means being coupled to said range measuring means for signaling said range measuring means to initiate a range measurement after a predetermined increment in travel of said vehicle whereby said summations are presented on said display means at regular intervals corresponding to said increments in vehicle travel.

21. A system according to claim 20 wherein said display means further comprises means for storing a summation of said successive range measurements for one of said objects after said one object is positioned relative to said vehicle to lie outside said beam of radiant energy.

22. A system according to claim 21 further comprising means coupled to said speed measuring means for weighting said range measurements to increase the value of said summations inversely with the speed of said vehicle.

23. A system for navigating a vehicle in a medium, said system comprising:

means responsive to the range between said vehicle and an object in said medium for storing a range measurement of said object;

means coupled to said storing means for displaying said range measurement;

means responsive to a speed of travel of said vehicle for addressing said storage means for selecting a storage bin corresponding to the location of said object; and

means coupled to said storage means for replacing a stored range measurement in an addressed bin with the sum of said range measurement and a subsequent range measurement.

24. A system for navigating a vehicle through a medium, said system comprising:

means for measuring range from said vehicle to objects submerged in said medium, said measuring means including means for illuminating said objects with a beam of radiant energy, said measuring means providing range measurements of objects positioned relative to said vehicle so as to be illuminated by said beam;

means for displaying a summation of successive ones of said range measurements for each of said objects, a value of an individual one of said summations for an individual one of said objects being retained when said illumination by said beam terminates;

means for coupling range measurements from said range measuring means to said display means; and

means for measuring a speed of travel of said vehicle, said speed measuring means being connected to said coupling mEans for initiating a coupling of one of said range measurements after a predetermined increment in travel of said vehicle whereby said summations are presented on said display means at regular intervals corresponding to said increments in vehicle travel.

25. A system for processing depth data of a medium in accordance with the travel of a vehicle through the medium, the system comprising:

means responsive to a measuring of depth for storing successive values of said depth data;

a source of clock signals;

means responsive to a speed of said travel for scaling a pulse repetition frequency of said clock signals in accordance with the magnitude of said speed;

a memory having a plurality of bins; and

means driven by said scaled clock signals for coupling individual values of said stored depth data into individual ones of said bins at intervals of time proportional to increments of said travel to provide an array of depth measurements corresponding to successive locations of said vehicle.