Claims:
1. A sonar array comprising:
at least two transducers; and
a steering system formed with a combination of mechanical beam steering and phased array beam steering, for steering the at least two transducers.
2. The array of claim 1, wherein the array further comprises, for mechanical beam steering, a single motor that moves the at least two transducers in tandem so that their radiating faces are parallel to each other resulting in a narrow, directed beam.
3. The array of claim 1, wherein the array further comprises, for mechanical beam steering, individual motors that move each of the at least two transducers in tandem so that their radiating faces are parallel to each other resulting in a narrow, directed beam.
4. The array of claim 1, wherein the array further comprises, for mechanical beam steering, individual motors that move each of the at least two transducers separately so that their radiating faces are at an angle to each other resulting in individual beams at different angles.
5. The array of claim 4, wherein the at least two transducers are moved separately using individual motors till the individual beams have minimal interference with one another.
6. The array of claim 1, wherein the array further comprises, for phased array beam steering, a spacing of more than 0.5 wavelength between the at least two transducers so as to increase directivity while still managing unwanted grating lobes.
7. The array of claim 1, wherein each of the at least two transducers has its own transmitter circuit and receiver circuit.
8. The array of claim 1, wherein the array is further operatively configured with a motor to enable the array for scanning an area 360 degrees around a vertical axis and/or a motor to enable the array for scanning an azimuth.
9. A sonar array comprising:
a frame; and
at least two staves affixed in the frame, wherein the staves are movable parallel to each other while being held in the frame in such a way that their angle to vertical/horizontal planes is adapted to be varied, while they remain parallel to each other, and wherein at least two staves are steered using a steering system formed with a combination of mechanical beam steering and phased array beam steering; and
a transducer mounted on each of the at least two staves.
10. The array of claim 9, wherein each stave is rotatably mounted, next to each other, on an axis running longitudinally across it, wherein each stave has a link rigidly connected to a rod, and wherein when the rod moves, the at least two staves rotate around their axes in such a manner that they remain mutually parallel while their angle to the vertical/horizontal planes changes.

, Description:
FIELD OF DISCLOSURE
[0001] The present disclosure relates generally to sonar technologies and, in particular, to a sonar array with hybrid steering.

BACKGROUND OF THE DISCLOSURE
[0002] The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Sonar, short for Sound Navigation and Ranging, is a well established technique for exploring and mapping water bodies such as oceans using sound waves since sound waves travel farther in the water than do radar and light waves. Sonar is used to develop nautical charts, locate underwater hazards to navigation, search for and map objects on the seafloor such as shipwrecks, and map the seafloor itself. There are two types of sonar—active and passive. Sonars use components termed as elements or transducers / transducer elements that can change electrical pulses into sound waves or vice-versa, or both.
[0004] An active sonar emits an acoustic signal or pulse of sound into the water. If an object is in the path of the sound pulse, the sound bounces off the object and returns an “echo” to the transducer. If the transducer is equipped with the ability to receive signals, it measures the strength of the signal. By determining the time between the emission of the sound pulse and its reception, the transducer can determine the range and orientation of the object.
[0005] A passive sonar on the other hand, is used primarily to detect noise from marine objects (such as submarines or ships) and marine animals like whales. Unlike active sonar, passive sonar does not emit its own signal, which is an advantage for military vessels that do not want to be found or for scientific missions that concentrate on quietly “listening” to the ocean. Rather, it only detects sound waves coming towards it using components that are also termed as elements/transducers. Passive sonar cannot measure the range of an object unless it is used in conjunction with other passive listening devices. Multiple passive sonar devices may allow for triangulation of a sound source.
[0006] Earlier designs of active sonar systems used a light bulb mounted on a spinning disk, the bulb configured to flash when an acoustical pulse was transmitted by an underwater transducer and again when the transducer detected a return echo from the bottom or a fish. Because the time between the transmitted pulse and the return echo was proportional to the distance that the acoustical beam had travelled, the arc that the disk had spun between the flashes could be calibrated to determine the depth to the bottom or the fish. Such products are still in use. However, many enhancements have also taken place such as use of strip chart recorders, cathode ray tubes (CRTs), and liquid crystal displays (LCDs) and circuitry to permit the retention and display of many acoustical pulses. The resulting display is a graphical representation of a history of the bottom depth beneath the boat and the location of any objects or fish that intervened. Such products are extremely useful for safe navigation in shallow waters and for finding the precise locations of fish and fish supporting underwater structures.
[0007] The sonar beam formed by a sonar device is conical in shape and targets outside the cone are not detected and remain invisible to the user. Likewise, a sonar device needs to be within range of a beam in order to detect it properly. Hence, a sonar device needs to be properly steered/aimed. Two methods are traditionally used to steer a sonar (and likewise, a sonar array, wherein the array comprises a plurality of transducers) to direct/aim/steer beam(s) being produced or to receive properly those being generated. The first method provides for the complete array/transducer to be mechanically steered. For instance, a transducer may be mounted over a steerable motorized shaft or multiple separately mounted transducers facing different directions may be used. A single flat plane array may be likewise used with an appropriate steering mechanism.
[0008] While such techniques offer some degree of improvement in increasing underwater area that can be viewed, they have limitations due to increased cost and complexity and potential reliability problems .of the moving parts in the motorized shaft. In a single flat pane array, while the electronic component are reduced to only one transmitter and/or receiver, it requires a large clearance diameter for the array to be mechanically steered.
[0009] The second method for steering a sonar is known as phased array method. Phased arrays were initially used for transmission of radio waves as elaborated hereunder but are now finding increasing use in sonar applications as well.
[00010] A phased array is a computer-controlled array of antennas which creates a beam of waves (for instance radio waves and now increasingly sound waves) that can be electronically steered to point in different directions, without moving the antennas. In an array antenna, the radio frequency current from the transmitter is fed to the individual antennas with the correct phase relationship so that the radio waves from the separate antennas add together to increase the radiation in a desired direction, while cancelling to suppress radiation in undesired directions. In a phased array, the power from the transmitter is fed to the antennas through devices called phase shifters, controlled by a computer system, which can alter the phase electronically, thus steering the beam of radio waves to a different direction.
[00011] Phased arrays were invented for use in military radar systems, to scan the radar beam quickly across the sky to detect planes and missiles. These phased array radar systems are now widely used, and phased arrays are spreading to civilian applications. The phased array principle is also used in acoustics, and phased arrays of acoustic transducers are used in medical ultrasound imaging scanners (phased array ultrasonics), oil and gas prospecting (reflection seismology), and military sonar systems. For sonar systems, the antennas are replaced by transducers ( interchangeably termed as elements herein), and radio waves by sound waves, other general principles remaining the same as described above..
[00012] An array factor is a mathematical factor in the directivity equation of an array antenna. It is the factor by which the directivity function of an individual antenna must be multiplied to get the directivity of the entire array. In a phased array, element (transducer) spacing has a large influence on the array factor. Larger transducer spacing results in a higher directivity. However, the transducer spacing is generally kept smaller than 0.5 wavelength to avoid the occurrence of grating lobes, wherein a grating lobe is another unwanted peak value in the radiation pattern of the array. For instance, in a 5 transducer array, increasing the transducer spacing towards 1 wavelength results in an increased directivity and grating lobe effect with maximum grating lobe amplitude equal to the main lobe magnitude at a transducer spacing of 1Xwavelength.
[00013] As elaborated above, a phased array does not need mechanical aiming. To minimize unwanted grating lobes that interfere with discriminating targets, the array is typically composed of many, small transducers spaced approximately one half wavelength apart. However, this requires a receiver for every transducer or row of transducers for receiving a sound beam. If the array is to be electronically aimed during transmission, a separate transmitter is required for every transducer or transducer row. As can be appreciated, this greatly complicates the electronic design of the array.
[00014] Hence there is a need in the art for a sonar array with steering that requires a lesser number of transducers while still controlling grating lobes, The array should be simpler and more economical in construction as well as signal processing as compared to a phased array. Besides, the array should be compact in size so as to require less clearance diameter to aim sonar beam generated as opposed to a single, flat pane, mechanically aimed array.
[00015] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[00016] In some embodiments, the numbers expressing quantities or dimensions of items, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[00017] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[00018] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[00019] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

OBJECTS OF THE INVENTION
[00020] Some of the objects of the present disclosure, which at least one embodiment herein satisfies are as listed herein below.
[00021] It is an object of the present disclosure to provide for a sonar array with steering that requires a lesser number of transducers to control/minimize grating lobes.
[00022] It is another object of the present disclosure to provide for a sonar array as above that is simpler and more economical in construction as well as signal processing as compared to a fully electronically phased array.
[00023] It is yet another object of the present disclosure to provide for a sonar array as above that requires less clearance diameter to steer sonar beam generated as opposed to a single, flat pane, mechanically steered array.

SUMMARY
[00024] This summary is provided to introduce a selection of concepts in a simplified form to be further described below in the Detailed Description. This summary is not intended to identity key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[00025] In an aspect, present disclosure elaborates upon a sonar array that can include at least two transducers; and a steering system formed with a combination of mechanical beam steering and phased array beam steering, for steering the at least two transducers.
[00026] In another aspect, the array can include, for mechanical beam steering, a single motor that moves the at least two transducers in tandem so that their radiating faces are parallel to each other resulting in a narrow, directed beam.
[00027] In yet another aspect, the array can include, for mechanical beam steering, individual motors that move each of the at least two transducers in tandem so that their radiating faces are parallel to each other resulting in a narrow, directed beam.
[00028] In an aspect, the array can include, for mechanical beam steering, individual motors that move each of the at least two transducers separately so that their radiating faces are at an angle to each other resulting in individual beams at different angles.
[00029] In another aspect, the at least two transducers can be moved separately using individual motors till the individual beams have minimal interference with one another.
[00030] In yet another aspect, the array can include, for phased array beam steering, a spacing of more than 0.5 wavelength between the at least two transducers so as to increase directivity while still managing unwanted grating lobes.
[00031] In an aspect, each of the at least two transducers can have its own transmitter circuit and receiver circuit.
[00032] In another aspect, the array can be operatively configured with a motor to enable the array for scanning an area 360 degrees around a vertical axis and/or a motor to enable the array for scanning an azimuth.
[00033] In an aspect, present disclosure elaborates upon a sonar array that can include a frame; and at least two staves affixed in the frame, wherein the staves can be movable parallel to each other while being held in the frame in such a way that their angle to vertical/horizontal planes can be adapted to be varied, while they remain parallel to each other, and wherein the at least two staves can be steered using a steering system formed with a combination of mechanical beam steering and phased array beam steering; and a transducer mounted on each of the at least two staves.
[00034] In another aspect, each stave can be rotatably mounted, next to each other, on an axis running longitudinally across it, wherein each stave has a link rigidly connected to a rod, and wherein when the rod moves, the at least two staves rotate around their axes in such a manner that they remain mutually parallel while their angle to the vertical/horizontal planes changes.
[00035] Various objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like features.

BRIEF DESCRIPTION OF DRAWINGS
[00036] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. The diagrams are for illustration only, which thus is not a limitation of the present disclosure, and wherein:
[00037] FIGs. 1A to 1C illustrate an array of six rows of transducers of a sonar array in accordance with an exemplary embodiment of the present disclosure.
[00038] FIGs. 2A and 2B illustrate a two transducer sonar array with individual tilting motor for each transducer in accordance with an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION
[00039] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[00040] In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent to one skilled in the art that embodiments of the present invention may be practiced without some of these specific details.
[00041] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[00042] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[00043] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. These exemplary embodiments are provided only for illustrative purposes and so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those of ordinary skill in the art. The invention disclosed may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Moreover, all statements herein reciting embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any components/items developed that perform the same function, regardless of structure). Also, the terminology and phraseology used is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed. For purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail so as not to unnecessarily obscure the present invention.
[00044] Thus, for example, it will be appreciated by those of ordinary skill in the art that the diagrams, schematics, illustrations, and the like represent conceptual views or processes illustrating systems and methods embodying this invention. The functions of the various components shown in the figures may be provided through the use of dedicated hardware as well as hardware capable of executing associated software. Similarly, any switches shown in the figures are conceptual only. Their function may be carried out through the operation of program logic, through dedicated logic, through the interaction of program control and dedicated logic, or even manually, the particular technique being selectable by the entity implementing this invention. Those of ordinary skill in the art further understand that the exemplary hardware, software, processes, methods, and/or operating systems described herein are for illustrative purposes and, thus, are not intended to be limited to any particular named component.
[00045] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various components or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[00046] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed aspect essential to the practice of the invention.
[00047] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing
[00048] In an aspect, present disclosure elaborates upon a sonar array that can include at least two transducers; and a steering system formed with a combination of mechanical beam steering and phased array beam steering, for steering the at least two transducers.
[00049] In another aspect, the array can include, for mechanical beam steering, a single motor that moves the at least two transducers in tandem so that their radiating faces are parallel to each other resulting in a narrow, directed beam.
[00050] In yet another aspect, the array can include, for mechanical beam steering, individual motors that move each of the at least two transducers in tandem so that their radiating faces are parallel to each other resulting in a narrow, directed beam.
[00051] In an aspect, the array can include, for mechanical beam steering, individual motors that move each of the at least two transducers separately so that their radiating faces are at an angle to each other resulting in individual beams at different angles.
[00052] In another aspect, the at least two transducers can be moved separately using individual motors till the individual beams have minimal interference with one another.
[00053] In yet another aspect, the array can include, for phased array beam steering, a spacing of more than 0.5 wavelength between the at least two transducers so as to increase directivity while still managing unwanted grating lobes.
[00054] In an aspect, each of the at least two transducers can have its own transmitter circuit and receiver circuit.
[00055] In another aspect, the array can be operatively configured with a motor to enable the array for scanning an area 360 degrees around a vertical axis and/or a motor to enable the array for scanning an azimuth.
[00056] In an aspect, present disclosure elaborates upon a sonar array that can include a frame; and at least two staves affixed in the frame, wherein the staves can be movable parallel to each other while being held in the frame in such a way that their angle to vertical/horizontal planes can be adapted to be varied, while they remain parallel to each other, and wherein the at least two staves can be steered using a steering system formed with a combination of mechanical beam steering and phased array beam steering; and a transducer mounted on each of the at least two staves.
[00057] In another aspect, each stave can be rotatably mounted, next to each other, on an axis running longitudinally across it, wherein each stave has a link rigidly connected to a rod, and wherein when the rod moves, the at least two staves rotate around their axes in such a manner that they remain mutually parallel while their angle to the vertical/horizontal planes changes.
[00058] Various objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like features.
[00059] In an aspect, proposed invention relates to multi-transducer phased sonar arrays. It deploys a hybrid approach using phased array techniques combined with mechanical, individual array transducer aiming to produce a sonar beam at an adjustable angle.
[00060] In an aspect, present disclosure elaborates upon a hybrid mechanical and phased array approach to aim beams from sonar arrays. Invention disclosed combines mechanical array steering with phased array steering techniques to accordingly steer the generated beams and/or receive the transmitted/reflected beams. Using design proposed, individual transducers can be spaced much more than 0.5 wavelength apart which is the usual limit in a phased array (also termed as electronically phased array herein), while still managing unwanted grating lobes. This reduces the number of transducers required as compared to a fully electronically phased array, with consequent reduction in array and signal processing complexity and costs, as compared to an electronically phased array that has transducers spaced at most at 0.5 wavelengths.
[00061] In another aspect, the use of multiple, mechanically aimed array transducers reduces the clearance diameter required to aim the beam(s) formed, as opposed to a single, flat plane, mechanically aimed array.
[00062] In this manner, the hybrid approach elaborated herein reduces electronic complexity compared to traditional electronically steered arrays (using the phased array method), achieves narrow beams with fewer transducers in the array, and reduces the rotational/clearance diameter required for mechanically steering a flat plane array.
[00063] FIGs. 1A to 1C illustrate an array of six rows of transducers of a sonar array in accordance with an exemplary embodiment of the present disclosure.
[00064] FIG. 1A illustrates a front view of a sonar array. FIG. 1B a side view and Fig.1C an isometric view, wherein the sonar array can have six row of elements/transducers 102.
[00065] In an aspect, the rows can be configured using, for instance, staves 104 as illustrated. The staves 104 can be horizontally affixed in frame 106.
[00066] In an aspect, staves 104 can be configured to move parallel to each other while being held in frame 106 in such a manner that their angle to vertical/horizontal planes can be varied, while they remain parallel to each other. For the purpose each stave can be rotateably mounted on an axis running longitudinally across it, shown as 108 in FIG. 1C and a number of such staves (for instance, six in exemplary embodiment being elaborated herein) can be mounted next to each other as illustrated. As shown in FIG. 1C, each stave 104 can have a link 110 and each link 110 can be rigidly connected to a vertical rod 112. As rod 112 moves up and down, staves 104 can rotate around their axes 108 in such a manner that they remain mutually parallel while their angle to the vertical/horizontal planes changes. A motor illustrated as 114 (FIG. 1A and FIG.1C) can be configured to provide the vertical up and down motion to rod 112.
[00067] It can be appreciated that mechanism as elaborated above is exemplary and any other mechanism that achieves the same purpose of rotating the staves in such a manner that their angle to the vertical/horizontal planes can be varied, while they remain parallel to each other can as well be used.
[00068] In another aspect, transducers/elements 102 can be mounted on staves 104 as elaborated further. The mechanical assembly as elaborated above can keep the transducers 102 on parallel planes in such a manner that the radiating faces of transducers 102 can remain parallel while their angle to horizontal changes as staves 104 are rotated, so as to steer/aim/direct a sonar beam appropriately.
[00069] It can be appreciated that mechanism as elaborated above is exemplary and any other mechanism that achieves the same purpose of rotating the transducers 102 in such a manner that their angle to the vertical/horizontal planes can be varied, while they remain parallel to each other can as well be used.
[00070] FIGs. 2A and 2B illustrate a two transducer array with individual tilting motor for each transducer in accordance with an exemplary embodiment of the present disclosure.
[00071] In an aspect, a two transducer array can be formed wherein a transducer 102 can be mounted on each stave 104 so that faces of the two transducers 102 are parallel to each other using the mechanical assembly elaborated above. Faces of transducers 102 can be kept at an angle to vertical (such angle being termed tilt angle), while remaining parallel to each other using the mechanical assembly elaborated above.
[00072] In another aspect, each transducer 102 can further have an individual tilting motor 202. Motor 202 can be used to tilt the face of each transducer 102 individually as required.
[00073] In an exemplary embodiment, with both transducers 102 tilted at same angle, a narrow beam can be formed, as shown as 116 in FIG.2B. Likewise, when all transducers of an array are tilted at the same angle, a beam of stronger intensity can be formed, , as showing at 116 in FIG. 1B.
[00074] In an aspect, as the tilt angle of the two transducers 102 is slowly varied from one another using tilting motor 202, beam formed can get wider and more grating lobes can appear.
[00075] In an aspect, at a tilt angle difference between the two transducers 102, two beams can be formed wherein the main lobe of each beam can be in null of the other, thereby minimizing interference between the beams generated by the two transducers. In this manner, beams generated from transducers 102 configured with tilting motors as elaborated above can be varied from a single narrow beam in one direction to two beams in different directions with minimal interference with one another, thereby increasing substantially the areas that can be searched/scanned by sonar beams generated by array of transducers configured as elaborated above.
[00076] In an exemplary embodiment, a motor can be further deployed to rotate the complete array assembly like a searchlight in order to scan a wider region.
[00077] In an exemplary embodiment, proposed invention can be used on a sonar device to search marine environment. The device can have a sonar array consisting of six staves configured one above another, each stave being 7 wavelengths apart from the next one. The staves can hold transducers/elements.
[00078] In an aspect, the six staves can be configured as elaborated in FIG. 1. A single tilting motor can mechanically tilt the six staves either up or down. The mechanical design can maintain the radiating face of each stave (such face holding the radiating faces of transducers/elements held on each stave) in a plane parallel to the planes of the other five rows.
[00079] In another aspect, each stave can be operatively connected to a transmitter and a receiver in order to perform the task of phase alignment of the transmit signals to each transducer, and the received echoes from each transducer.
[00080] In an exemplary embodiment, to perform phase alignment, the array can be aimed down from horizontal such that the radiating face of all six staves points at an angle of fifteen degrees down from horizontal. To form the transmitted beam at 15 degrees, the top stave can be excited first, with a fixed time delay to starting each of the additional five staves. The result can be a sound beam projected down 15 degrees from horizontal. This is well known phased array technology.
[00081] Similarly, in receive mode, echo of beam sent out by the array arrives first at the bottom stave and propagates one by one up to the top stave.
[00082] As can be appreciated, the delay in echo received at one stave to the next depends on the spacing between the staves. To align the signals, the echo from the bottom stave can be electronically delayed or shifted to be in phase with echoes arriving at the top stave, and likewise for the remaining staves.
[00083] In an aspect, the delay from one stave to the next is = (sine(tilt_angle) x (stave spacing)). For example with a angle of fifteen degrees down from horizontal, and stave spacing of seven wavelengths, the delay per stave is (SIN(15) * 7) = .259 * 7 = 1.812 wavelengths delay from one stave to the next.
[00084] In this manner, a sonar array combining mechanical beam steering and phased array beam steering can be formed thereby obviating the disadvantages of solely mechanical or solely phased array steering. Invention proposed reduces the number of transducers required to control grating lobes, compared to a fully electronically phased array, because the individual transducers can be spaced much more than 0.5 wavelengths, while still managing unwanted grating lobes. Array and signal processing complexity and costs are reduced compared to phased array steering with transducers spaced at 0.5 wavelengths since, with increased spacing, number of transducers can be reduced. The use of less transducers reduces the clearance diameter required to steer the beam using mechanical beam steering, as opposed to a single, flat plane, mechanically steered sonar array without phased array steering.
[00085] As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two components are coupled to each other or in contact each other) and indirect coupling (in which at least one additional component is located between the two components). Therefore, the terms “coupled to” and “coupled with” are used synonymously. Within the context of this document terms “coupled to” and “coupled with” are also used euphemistically to mean “communicatively coupled with” over a network, where two or more devices are able to exchange data with each other over the network, possibly via one or more intermediary device.
[00086] Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to components or steps in a non-exclusive manner, indicating that the referenced components or steps may be present, or utilized, or combined with other components or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one component/item from the group, not A plus N, or B plus N, etc.
[00087] While some embodiments of the present disclosure have been illustrated and described, those are completely exemplary in nature. The disclosure is not limited to the embodiments as elaborated herein only and it would be apparent to those skilled in the art that numerous modifications besides those already described are possible without departing from the inventive concepts herein. All such modifications, changes, variations, substitutions, and equivalents are completely within the scope of the present disclosure. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims.

ADVANTAGES OF THE INVENTION
[00088] The present disclosure provides for a sonar array with steering that requires a lesser number of transducers while controlling/minimizing grating lobes.
[00089] The present disclosure provides for a sonar array as above that is simpler and more economical in construction as well as signal processing as compared to a fully electronically phased array
[00090] The present disclosure provides for a sonar array as above that is compact in size so as to require less clearance diameter to steer beam generated as opposed to a single, flat pane, mechanically steered array.