WO2011063515A1

WO2011063515A1 - Integrated sonar transceiver and transducer assembly

Info

Publication number: WO2011063515A1
Application number: PCT/CA2010/001869
Authority: WO
Inventors: Didier Caute; Frederick David Cotaras; Karl Kenny; Brian Edward Cooke
Original assignee: Marport Canada Inc.; General Dynamics Canada
Priority date: 2009-11-27
Filing date: 2010-11-29
Publication date: 2011-06-03

Abstract

A system and method are provided that mitigate the amount of cabling required in a large transducer array, reduce the size of the equipment (e.g. inboard processing) required in a sonar room, reduce the effects of noise on the signals, and provide greater flexibility to individual transducer elements in the array, by modifying existing transducer assemblies to include an onboard or proximal data processing module that is software defined and performs digital processing close to the transducer element thus requiring only digital data and power wires to extend from the transducer array to the operations room. In this way, the amount of cabling required is significantly reduced saving both cost and space in the marine vessel (or towed equipment). Moreover, by placing the processing close to or within the transducer assembly, the electronics can be water cooled thus eliminating the need for large and expensive heat sinking equipment, or air conditioning, or water cooling, etc.; e.g. in the sonar room.

Description

INTEGRATED SONAR TRANSCEIVER AND TRANSDUCER ASSEMBLY

[0001] This application claims priority from U.S. Provisional Application No. 61/264,758 filed on November 27, 2009, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

[0002] The following relates to sonar transducers generally and particularly to an integrated sonar transceiver and transducer assembly.

BACKGROUND

[0003] Large transducer arrays are currently used in many applications, including antisubmarine warfare sonar systems. Such systems utilize a large frame supporting an array 2 of transducers 3, the frame typically being mounted on the hull of a marine vessel 5 as shown in Figure 1. The frame supports an arrangement of transmit/receive transducers 3 in an array 2, which typically utilize single electro-acoustic transducer elements 3. Examples of the arrangement of the transducers 3 can be seen in Figures 2 to 4. In typical applications, the frame carrying the transducer array 2 is installed on a boat bow (e.g. as shown in Figure 1), a submarine bow, or in variable depth sonar equipment towed behind a marine vessel 5.

[0004] As can best be seen in Figure 2, a standard arrangement of transducer elements

3 is typically arranged in multiple staves, in this example with 4 transducers per stave. The frame holds the transducer elements 3 in a given geometry, in the example shown, a cylindrical shape. Figure 3 illustrates a cylindrical example with square faced transducer elements 3, and Figure 4 illustrates an example using a smaller cylinder when compared to Figures 2 and 3.

[0005] A twisted pair wire is outputted from each and every transducer 3, with shielding often being included. Groups of these wires run together in large cables 4 that must extend towards a sonar operations room 6 as shown in Figure 1. The operations room 6 houses the operator console 8, which is connected to sonar transceiver, processing, and heat sinking (collectively referred to as 'inboard processing' 7 in Figure 1) in a sonar room (not shown) at some other location in the marine vessel 5. Not only is a long run of relatively large cabling

4 required, the size of the cabling 4 and thus the room needed increases with the number of transducer elements 3. Also, the inboard processing 7 is typically quite large thus taking up significant room in the marine vessel. For example, in some applications, the cables 4 can be as long as 30 m. Since the signals being carried by the cabling 4 from the transducer elements 3 to the inboard processing 7 are analog, noise can be an issue, which requires the aforementioned shielding, and thus typically increases the size of the cabling 4 and the overall cost.

SUMMARY

[0006] In one aspect, there is provided an integrated sonar transceiver and transducer assembly, the assembly comprising: a housing; an electro-acoustic transducer element, wherein a portion of the transducer element has been reduced in size to provide additional room in the housing; a software defined processing module included in the housing in place of a normally existent transformer, the processing module comprising a configurable electronics board providing a linear power amplifier and matching transformer; and a connection comprising data and power wires to communicate with and power the processing module to operate the transducer assembly.

[0007] In another aspect, there is provided a sonar system comprising a plurality of transducer assemblies as described above, a switching box, a data processing module bus connecting the plurality of transducer assemblies to the switching box, and a connection to an operator console on a vessel for controlling the plurality of transducer assemblies.

[0008] In yet another aspect, there is provided a method for assembling an integrated sonar transceiver and transducer assembly, the method comprising: modifying a housing configured for an existing transducer element by reducing a portion thereof in size to provide additional room in the housing; removing a transformer from the housing; incorporating a software defined processing module included in the housing in place of the transformer, the processing module comprising a configurable electronics board providing a linear power amplifier and matching transformer; removing an existing connection from the transducer element; and providing a connection comprising data and power wires to communicate with and power the processing module to operate the transducer assembly.

[0009] In yet another aspect, there is provided an integrated sonar transceiver and transducer assembly, the assembly comprising: a first housing configured for an electro- acoustic transducer element, the transducer element comprising a transformer, and an active element; a second housing attached to an upper end of the first housing, the second housing being sized to contain a software defined processing module, the processing module comprising a configurable electronics board, the processing module being coupled to the transformer; and a connection comprising data and power wires to communicate with and power the processing module to operate the transducer assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Embodiments will now be described by way of example only with reference to the appended drawings wherein:

[0011] Figure 1 is schematic diagram illustrating a hull mounted transducer array of the prior art comprising inboard processing a distance from the array in a sonar room.

[0012] Figure 2 is a perspective view of a prior art transducer array.

[0013] Figure 3 is a perspective view of another prior art transducer array.

[0014] Figure 4 is a perspective view of yet another prior art transducer array.

[0015] Figure 5 is a schematic diagram of a prior art Tonpilz type transducer element.

[0016] Figure 6 is a schematic diagram illustrating a hull mounted transducer array comprising integrated transducer assemblies to remove inboard processing from the sonar room and reduce the amount of cabling.

[0017] Figure 7 is a comparative view showing a prior art transducer assembly against the integrated transducer assembly in perspective, partially transparent views.

[0018] Figure 8A is a cross sectional view of the integrated transducer assembly shown in Figure 7.

[0019] Figure 8B is_^ a cross sectional view of another embodiment of the integrated transducer assembly utilizing an existing transformer.

[0020] Figure 9 is a schematic diagram illustrating the connectivity of a plurality of integrated transducer assemblies.

[0021] Figure 10 is a schematic diagram illustrating one configuration for the data processing module integrated with a transducer in the integrated transducer assembly.

[0022] Figure 11 is a logic diagram illustrating an FPGA implementation of a side scan sonar or echo sounder receiver.

[0023] Figure 12 is a logic diagram illustrating an FPGA implementation of a modem receiver. [0024] Figure 13 is a logic diagram illustrating an FPGA implementation of a modem transmitter.

[0025] Figure 14 illustrates voltage tracking an output voltage using a Class-H amplifier.

[0026] Figure 15 is a block diagram schematic of the amplification stage shown in Figure 10.

DETAILED DESCRIPTION OF THE DRAWINGS

[0027] It has been found that to: i) mitigate the amount of cabling 4 required in a large transducer array 2, ii) reduce the size of the equipment (e.g. inboard processing 7) required in the sonar room, iii) reduce the effects of noise on the signals, and iv) provide greater flexibility to individual transducer elements 3 in the array 2; existing electro-acoustic transducer assemblies can be modified to include an onboard or proximal data processing module that is software defined and performs digital processing close to the transducer element, 3 thus requiring only digital data and power wires to extend from the transducer array 2 to the operations room 6. In this way, the amount of cabling 4 required is significantly reduced saving both cost and space in the marine vessel 5 (or towed equipment). Moreover, it has been recognized that by placing the processing close to or within the transducer assembly 2, the electronics can be water cooled thus eliminating the need for large and expensive heat sinking equipment, e.g. in the sonar room as has been required in the past.

[0028] It will be appreciated that although the following examples may refer to particular types of transducer assemblies and transducer elements for underwater applications (e.g. Tonpilz type transducers), the following principles equally apply to any electro-acoustic transducer assembly and transducer element. For example, these principles may be applied to piezoelectric transducers, such as those using ceramic elements (also known as

"piezoceramic" transducers), magnetorestrictive transducers, flextensional transducers, barrel stave transducers, etc. As such, in general, the following relates to the adaptation of a transducer assembly by reducing a portion of it transducer element (e.g. by reducing the size of a rear mass and removing a transformer) or by attaching to an existing housing to include a software defined processing module. By incorporating the software defined processing module close to the transducer element, the above-noted advantages can be achieved. [0029] Turning now to an example for illustrating the principles herein, Figure 5 shows a conventional Tonpilz type transducer element 3. As is known in the art, the Tonpilz transducer 3 involves the use of axi-symmetric structures consisting of a sandwich of ceramic drive elements between metal end masses. Tonpilz lumped mode transducers are typically operated in the range from 1 kHz to 50 kHz, and is a common sonar projector.

[0030] The Tonpilz transducer 3 comprises a large piston head mass driven by a slender drive section which gives it the cross-sectional appearance of a mushroom. This concept along with a tail mass allows a compact mechanism for obtaining high output at midrange frequencies without the need for an excessively long piezoelectric ceramic or

magnetorestrictive drive stack. The cross section shown in Figure 5 shows a 33-mode driven ring-stack of four parallel wired PZT rings driving a relatively light but stiff mass with a comparatively heavy tail mass on the other end. Other parts shown include mechanical isolation, a housing, a transformer with tuning network, rubber enclosure around the head, and electrical underwater connector. The stack is held under compression by a stress rod and, in other examples, a compliant conical disc or Bellville washer that decouples the stress rod and maintains compressive stress under thermal expansion. In some designs, the circumference of the PZT stack is also fibreglass wrapped for added strength under shock. Typically, the head is made from aluminum, the tail made from steel, the stress rod high strength steel, and the piezoelectric rings ceramic (e.g. Navy Type I or III). The housing is usually steel, and the water tight boot made from neoprene or butyl rubber and sometimes polyurethane for short term immersion. The rubber boot is vulcanized to the head to ensure good bonding with no air pockets, which would unload the transducer and reduce the radiation resistance.

[0031] The goal with a Tonpilz transducer 3 is to attain the greatest possible motion of the head piston and radiate as much power as possible near and above mechanical resonance. Although operation below resonance is possible, the transmitting voltage response (TVR) typically falls off at 12 dB per octave. The characteristics and operation of Tonpilz transducers 3 is well known in the art and thus further details thereof can be omitted.

[0032] Along with conventional Tonpilz transducers 3, such as in Figure 5, there also exists flexural head Tonpilz transducers 3 and double head mass Tonpilz transducers 3. Such transducers 3 can be used for sonar imaging, communications, and positioning. As noted above, it has been found that to mitigate the amount of cabling 4 required in a large transducer array 2, reduce the size of the equipment required in the sonar room, reduce the effects of noise on the signals, and provide greater flexibility to individual transducer elements 3 in the array 2, a software defined data processing platform can be integrated into or otherwise coupled to an existing or custom-built transducers, in particular a Tonpilz-type transducer assembly 11 as shown in Figure 6. The software defined platform is integrated in order to provide a matching transformer, transmitter, receiver onboard digital signal processing (DSP) (e.g. down sampling, filtering, beam steering, beam forming, etc.), and digital format of data inputs and outputs (compared to analog currently) while being fully configurable (i.e. software defined). By integrating digital data processing close to or within the transducer assembly 11 itself, the amount of cabling 12 required is reduced and much of the inboard processing 7 that was required in the example shown in Figure 1 can be eliminated. As such, a modified transducer array 10 can be controlled via software from an operator console 13 as shown in Figure 6 with a reduced amount of cabling 12 as is also illustrated schematically.

[0033] It can be appreciated that the reduction in cable size and weight provides numerous advantages. In prior systems, the cable 4 that is required to carry the power and transmit wires, needs to provide shielding to the receive wire for immunity to external noise. Because of this, one cable per transducer element 3 is required from the transducer array 2 to the inboard processing 7. In the integrated solution described herein, a relatively lighter weight digital cable can be used that is generally small, e.g. using plastic fibre optic cabling. The power supply to the transducer elements 3 can also be provided through a single power distribution cable that is proximal to the transducer therefore reducing the number of cables required. The digital cable can then be connected to a network switching device 31 (see Figure 9) near the transducer elements 3 allowing a single cable to be run from the switching box 31 to the inboard processing 7.

[0034] Turning now to Figure 7, a partially transparent perspective view of an integrated software defined transducer assembly 11 is shown in the right hand portion of the figure along side an existing Tonpilz-type transducer assembly 14. As can be seen from the comparison shown in Figure 7, the existing transducer assembly 14 can be modified to make room for an onboard data processing module 26 and thus in some applications will not alter the existing mounting hardware or frame design. Beginning from the base, the front mass 15, front boot 16, and the ceramic stack 17 of the existing transducer assembly 14 can remain as is, thus eliminating the need to redesign the overall system which would be required with a modified (e.g. smaller) ceramic stack 17. In a first size reduction, the rear mass 19 can be shortened to a reduced rear mass 18 by changing materials as will be explained in greater detail below (e.g. from steel to Tungsten). This moves the isolation and compartment separation layers 21 , 23 down the body of the transducer assembly 14 to create more room within the housing 25 (i.e. layers 20, 22 are lower in housing 24 with respect to their predecessors 21 , 23 respectively in housing 25). In addition to the additional space created through a shorter rear mass 18, a compact data processing module 26 has been designed that not only incorporates DSP processing, etc. as discussed above, the module 26 itself replaces the existing transformer 27 that in existing designs consumes a great proportion of the housing 25. Since analog to digital conversion and digital processing occurs in the integrated transducer assembly 11 , the previously used analog output cable 29 can be replaced with a power-Fibre connector 28 or pigtail connector (not shown) that provides a digital data wire and a power wire to the module. Figure 8A provides a cross- sectional view of the integrated transducer assembly shown in Figure 7.

[0035] The data processing module 26 can be an adaptation of one or more

components of a software defined platform, such as that shown in PCT Application No. PCT/CA2009/001118, which was filed on August 1 , 2009, is entitled "Multi-Function Broadband Phased-Array Software Defined Sonar System and Method", and published under WO 2010/017629; the entire contents of which are incorporated herein by reference. Such an adaptation or custom-built solution enables the desired processing capabilities to fit within a constrained space while allowing a bigger transformer to be incorporated if the application requires the need to source more power to the transducer components. Further detail of the data processing module 26 will be provided later.

[0036] To achieve the integrated design shown in Figures 7 and 8A, the overall size of the integrated transducer assembly 11 should not be increased with respect to an existing assembly 14, since the overall geometry of the transducer itself defines the beam pattern performance of the overall system. With this constraint, a defined size is dictated and, as discussed above, the existing transformer 27 is replaced with a full electronics package (e.g. module 26). Also, to find additional space, the rear mass 19 can be reduced in size by selecting a higher density material for reduced rear mass 18, e.g. tungsten (approximately 19400kG/m³), when compared to steel which has a density of approximately 7700kG/ m³. As such, for the same weight (which maintains the ratio between the front mass 15 and the rear mass 18, 19 which defines the acoustic performance), the volume can be reduced up to 2.5 times and, since the diameter can be kept constant, the height of the rear mass 18 is reduced up to 2.5 times providing the required space on the back of the assembly 11 to enable the data processing module 26 to be accommodated. As noted above, the ceramic stack 17 and front mass 15 need not be changed. In the end, the performance measures can be kept the same while creating the room necessary to provide the advantages associated with processing the data immediately at the transducer before cabling the data to a distant location.

[0037] To address the possibility of mechanical shock absorption, the data processing module 26 can be held in place inside the aluminum housing 24 with a resin. Resin also allows heat to dissipate from the electronic board(s) to the housing 24, which is in contact with water thus allowing a water cooling effect for the electronics. The housing 24, which can be aluminum, stainless steel, titanium, etc., can also be provided with EMC shielding to address RF waves from the electronics. This also reduces the susceptibility to external RF waves.

[0038] As noted above, in one example, the cabling 12 from the integrated transducer assembly 11 provides a fibre optic data wire, however, to reduce the amount of space required on the back of the transducer assembly 11 , a pigtail connector can instead be used. The output cable for the integrated transducer assembly 11 thus provides fibre optic transmit, fibre optic receive, main power supply positive, and main power supply negative. This reduces the cabling 12 requirements when compared to existing transducer assemblies 14. In the existing designs, every cable 4 is independent with only the power cable being split into every element near the individual transducers 3. Also, in the current solutions, the twisted pair cable used for transmitting analog signals in transmit creates electrical noise and coupling with other cables in its vicinity, and in receive, the cable length may pick up some electrica noise from the vessel 5 around which reduces the signal-to-noise ratio, thus decreasing the detection range of the sonar application.

[0039] By placing the data processing module 26 close to the back of the transducer components 15, 17, 18, the issues with the current analog transmission of data can be greatly mitigated.

[0040] It can be appreciated that although the examples shown herein integrate the data processing module 26 directly within an existing housing 24, 25, if space permits, an appropriately sealed additional compartment (not shown) can be attached or otherwise coupled to the transducer assembly 11. In the present example, fibre optic wires are used for carrying digital signals instead of a twisted pair cable (which could also be used) since fibre optics by nature radiate very low emissivity in RF around the fibre cable, which can provide better immunity to RF triggered mines by reducing the RF signature of the hull of the vessel 5 or a submarine, etc.

[0041] Providing the data processing module 26 inside the transducer housing 24 also allows improved maintenance by enabling self diagnostics embedded in the transducer itself. Since each integrated transducer assembly 11 has its own data processing module 26, each data processing module 26 can perform for its corresponding transducer 11 , an impedance check of the transducer element. Also, the data processing module 26 can include circuitry to measure current and voltage applied to the transducer while transmitting, and can perform complex impedance checking without any effects from the cable 2 between the transducer 11 and the sonar room. Also by having the data processing module 26 in the transducer housing 24, the temperature and moisture of the immediate environment can be monitored through its sensor processing capabilities.

[0042] As will be shown and described in greater detail below, the data processing module 26 can be configured with a 3-axis accelerometer to sense the acceleration relative to gravity. Also, a 3-axis gyro sensing the rate of movement and a 3-axis magnetometer sensing the magnetic field can be provided. By providing these sensors, the data

processing module's processing capabilities can embed a fusion algorithm to get inertial data calculated for each and every data processing module 26 (since each transducer 11 includes a data processing module 26) with each module sharing pitch and roll information at a minimum (if acceleration is not above MEMS sensor limit) to enable an average value to be computed to remove noise and statistically calculate the movement of the transducer assembly 11. This enables compensation procedures to be used during beam forming and beam steering among other things.

[0043] Figure 8B provides a cross-sectional view of another embodiment of the integrated transducer assembly 1', denoted with the suffix (') for clarity. In the embodiment shown in Figure 8B, the data processing module 26 is incorporated into an auxiliary housing 32 that is attached or otherwise coupled to an existing transducer housing 25. In this way, the existing transducer assembly 14, including the existing transformer 27 are used whilst the digital processing remains close to the transducer components to achieve the

advantages described herein.

[0044] Figure 9 illustrates a high-level schematic showing the connectivity of the data processing modules 26. As shown in Figure 9, in some embodiments, the data processing modules 26 can be linked to each other to create a data processing module bus 30 enabling the synchronization of the data processing modules 26 and thus the transducers 11. Each data processing module can perform a beam steering operation by using a delay and sum scheme, recalculated every time the movement of the platform is large enough to require readapting the delays in the beam steering operation. In the receive mode, every data processing module 26 can perform a sub-channel beam forming process or, by sharing data with all other nodes as shown in Figure 9, each data processing module 26 can be in charge of one beam in the beam forming operation. Also, as noted above, the transducers 11 can be cabled to the switching box 31 and a single cable run to the inboard processing 7 using such an arrangement. This harnesses the software defined capabilities of the data processing module 26, which provides flexibility depending on the application. The data processing module 26 can also be used in sampling and forwarding digitally sampled data to the operations room processor for beam forming done at that level. In this case, all data processing modules 26 can be synchronized over the fibre optic wires using for example Precision time Protocol (PTP), and then allowing a 10ns accuracy of synchronization for example of all units. As such, it can be appreciated that the data processing modules 26 provide both flexibility for each transducer assembly 11 and flexibility across the entire system.

[0045] In order to provide the capabilities discussed above, the data processing module 26 should be designed in a compact package that also replaces the transformer 27 of existing designs. Figure 10 illustrates one example architecture for the data processing module 26. It can be appreciated that the architecture shown in Figure 10 not only provides expected functionality for accommodating various applications, since it is software defined, it is scalable and can permft other sensor types or data processing capabilities to be added as necessary or desired.

[0046] The data processing module 26 comprises a processor 50 for handling various operations such as powering and acquiring data from various sensors as well as data communications via one or more communication interfaces 78. Also provided is a field- programmable gate array (FPGA) 52, which enables the data processing module 44 to be fully configurable for various applications including dynamic reconfigurations "on-the-fly". The FPGA 52 also enables complex beam forming and beam steering operations to be executed in various applications as will be explained in greater detail below. The processor 50, among other things, outputs configuration information to the FPGA 52 via an EMI bus interface 100 in this example. The FPGA 52 then controls a low resolution polarization digital-to-analog convertor (DAC) 55 to generate an analog signal for adjusting the polarization of a linear amplifier 56. The polarization controls the voltage applied by a DC/DC convertor 151 (see also Figure 15) that provides power to a class B or D amplifier being used. As discussed below, by using a class B amplifier with the DC/DC convertor 151 enables a class H amplifier to be created. By combining the DC/DC convertor 151 with a class D amplifier, class D behaviour is experienced. The FPGA 52 also provides analog data to the amplifier 56 via a pair of DAC channels 57 (e.g. channel A and channel B to be discussed below) over a parallel bus. The 2 DAC channels 57 transmit the waveform to the amplifier 56, which signals contain transistor polarization control. In general, once the processor 50 configures the FPGA 52, the FPGA 52 is configured to provide DC/DC conversion thus applying a power voltage to the amplifier 56, and provides the amplifier 56 with internal polarization for the pair of DAC channels 57. The processor 50 may then be used to send a start command to the FGPA 52, which then sends the signals to the DACs 55, 57 to operate the linear amplifier 56. Further detail regarding the linear power amplifier 56 will be provided below making reference to Figures 14 to 16.

[0047] The linear power amplifier 56 drives a transducer channel 58 for driving the transducer components 15, 17, 18. An analog signal is received and processed by a limiter and amplifier stage 60. The signal is then processed by a direct conversion stage 62, which provides oversampling to allow greater sensitivity and to increase the size of the vector providing better resolution. The received and sampled signal is then processed by the FPGA 52 and the results may be stored in RAM 86. Shown in Figure 10 are fast Fourier transform (FFT) and inverse FFT (iFFT) functional block 106 as well as a digital data storage (DDS) block 108 to illustrate example capabilities provided by the FPGA 52 and it will be appreciated that other functions are possible. Figures 11 to 13 illustrate how the FPGA's- internal connections can be made to implement various applications. In Figure 11 , an echo sounder/side scan receive implementation is shown. It can be appreciated that the transmit implementation involves playing a file (e.g. .wav file) over the DACs 57 connected to the linear amplifier 56. In Figure , a streaming block is shown, which in this example is a constant acquisition block, which samples with accuracy (accurate phase and time) and storing samples in RAM or other memory. The processing block shown in Figure 11 executes a dechirp algorithm for demodulation and downloads samples out of memory (Nb points = FFT size). The processing block then processes the points and records the result in memory after processing. The processor 50 can obtain the processed points directly from the FPGA 52. It will be appreciated that a state machine would be used for managing the blocks shown in Figure but is not shown for simplicity of explanation. [0048] In Figure 12, a receiving portion of a modem implementation is shown. The streaming block in Figure 12 operates in a manner similar to that shown in Figure 11 to receive data for OFDM incoherent demodulation. The streaming block is a constant acquisition block, sampling with accuracy and storing samples in memory. The processing block in Figure 12 performs a spectral analysis (FFT + dB conversion) and the FPGA 52 provides the processed points to the processor 50. Again, the underlying state machine is not shown for simplicity of explanation.

[0049] Figure 13 illustrates a transmit portion of a modem implementation. The diagram shown in Figure 13 illustrates an example implementation for an OFDM emitter. The processor 50 can provide a data bitstream to the FPGA 52 and the FPGA 52 is in charge of modulating the signal and driving the power amplifier 56 through the DAC channels 57. It can be appreciated that the configuration shown in Figure 13 is software defined and thus can be configured for different applications.

[0050] The FPGA 52 can be reprogrammed for different applications via a reprogram (R) input. It may also communicate with the processor 50 via a parallel bus via an EMI component 100. The processor 50 comprises a real time clock (RTC) 96, which saves the current time and date, similar to any computing device. The RTC 96 can also be used to keep the time when the processor 50 is off, however, the battery 46 would need to be connected in order to maintain the RTC 96. A watch dog timer (WDT) 98 is also shown in Figure 3A and is a standard peripheral generating a reset of the processor 50 when the processor 50 is not normally executing code. An I/O peripheral component 102 is provided for communicating with peripherals. An electrically erasable programmable read-only memory (EEPROM) 90 may also be used to provide native memory for the subsea data module 10. This contrasts other memory such as an SD card 84, which can be unplugged. The EEPROM 90 can be relied on to contain a dedicated file system for FPGA firmware (FPGA1 or 2), configuration/option recording, echo sounder configurations, and error tracking.

[0051] When deployed, the data processing module 26 can rely on external power 46, which powers a power management module 64 for providing power management. The processor 50 is also responsible for obtaining data from an analog to digital convertor (ADC) 68 which interfaces with various sensors 22 such as temperature, pressure, and other gauges (e.g. using a Wheatstone bridge). The processor 50 in the example shown also provides an I/O interface with a humidity sensor 70 to detect water leakage in the subsea data module 10, as well as a 3 axis accelerometer 72 (via an ADC 74) and a 3-axis gyro 76 to measure movement of the data processing module 26 and thus the transducer assembly 11.

[0052] In addition to obtaining sensor and other data, the subsea data module 10 can provide a power and data connection from the processor 50 to various communication interfaces 78. Any suitable interfaces can be provided but by way of example, only, Figure 10 illustrates a USB interface, an RS232 interface with an optional optic fibre driver and connector 80, Ethernet, and external wake up PPS that can interface with a hardware reset signal. The hardware reset is an input to create a reset of the electronics, and the precise positioning service (PPS) is a trigger input allowing a synchronization with accuracy for the RTC 96. For example, the PPS can be connected to a GPS unit (not shown). It can therefore be seen that the processor 50 provides the ability to handle numerous interfaces to accommodate numerous types of data for various applications. For example, the FPGA 52 can be programmed to provide a specific sonar application while measuring sensor data to monitor the surrounding environment to assist in computations or for data logging purposes.

[0053] It will be appreciated that any module or component exemplified herein that executes instructions may include or otherwise have access to computer readable media such as storage media, computer storage media, or data storage devices (removable and/or non-removable) such as, for example, magnetic disks, optical disks, or tape. Computer storage media may include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. Examples of computer storage media include RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by an application, module, or both. Any such computer storage media may be part of the data processing module 26, or accessible or connectable thereto. Any application or module herein described may be implemented using computer readable/executable instructions that may be stored or otherwise held by such computer readable media.

[0054] It has been recognized that the subsea data module 10 should utilize a linear amplifier 56, which is able to provide a high voltage, e.g. more than AC lOOOVrms while being powered by a low voltage source, e.g. DC 100V. The amplifier's efficiency is an important consideration for at least the reason that there will be many data processing modules 26 being used, i.e. one per transducer assembly 11. Typically, sonar/sounder applications use Class B (push-pull) amplifiers to achieve linearity. However, Class B configurations are known to have losses. In order to reduce the Class B lowers, a DC/DC converter 151 (see Figure 15) is used in the amplifier 56 to power the amplifier in a Class H configuration as shown in Figure 14, which enables the voltage rails to more closely follow the signal.

[0055] Figure 15 illustrates the control paths for the amplifier 56 shown in Figure 10. As discussed above, the processor 50 provides configuration information to the FPGA 52, which generates and sends the signals to the amplifier 56, e.g. to drive the transducers

components 15, 17, 18. As shown in Figure 15, the polarization DAC 55 controls a DC/DC convertor 151, which applies a power voltage to the linear amplifier 56. The waveform DAC stage 57 is also controlled by the FPGA 52 and provide the waveform to the amplifier 56, which also includes transistor polarization.

[0056] It may be noted that typically the amplifier output impedance is much lower than the transducer input impedance. In prior applications, a matching transformer (e.g. existing transformer 27) is used inside the transducer assembly 14 to present the same impedance to the distant amplifier output impedance, where usually a step-up transformer is used. Such a transformer is also used for tuning the transducer components to the transformer 27 by compensating the capacitor from the transducer model, and then optimizing the resonance to the proper frequency when working in a narrow band. The stepping up from the transformer 27 inside the transducer assembly 14 is limited, because stepping up in transmit means stepping down in receive, decreasing the sensitivity.

[0057] The solution proposed herein can take advantage of the digital processing being close to the transducer components. The transformer 156 in the linear power amplifier 56 can be used as a matching and step up transformer, which can be done without limits. The transformer 156 can be used as a step-up transformer with a high ratio step-up, since the receive (Rx) is close to the transducer components an does not need to come after the transformer 156, but directly connected to it, allowing maximum sensitivity without noise in between. The transformer 156 can also be used for matching to allow maximum power transfer efficiency in the bandwidth of interest. Since the integrated transducer 11 preferably adapts an existing transducer assembly 14 with digital processing with all the advantages discussed above, the bandwidth of interest would typically be known on an application by application basis depending on the existing transducer components being used.

[0058] The high stepping transformer ratio (e.g. could be around 12 or 15) allows a fairly low voltage rating MOSFET to be accommodated, allowing better performances in the amplification stage 56. For example, a 200V MOSFET can be used with 100VDC allowing a 1500V output peak onto the transducer with a 15 ratio. Being software defined, the data processing module 26 allows the applied voltage to be tuned knowing what performance the transducer can achieve, allowing a software tuning of the transducer assembly 11. It may be noted that this does not require the transformer 156 to be larger.

[0059] It can be appreciated that because the software defined architecture is implemented within the transducer assembly 11 , it does not need to adapt to various transducer types, so the transformer can be decided once when designing for a known transducer element 3 since it merges 2 functions : step up and matching

[0060] Although the above has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the scope of the claims appended hereto.

Claims

Claims:

1. An integrated sonar transceiver and transducer assembly, the assembly comprising: a housing; an electro-acoustic transducer element, wherein a portion of the transducer element has been reduced in size to provide additional room in the housing; a software defined processing module included in the housing in place of a normally existent transformer, the processing module comprising a configurable electronics board providing a linear power amplifier and matching transformer; and a connection comprising data and power wires to communicate with and power the processing module to operate the transducer assembly.

2. The assembly according to claim 1 , wherein a rear mass of the transducer element reduced in size by replacing its existing material with a higher density material.

3. The assembly according to claim 2, wherein the higher density material is Tungsten.

4. The assembly according to any one of claims 1 to 3, wherein the connection is provided by replacing a normal analog cable with a digital data wire and power wire.

5. The assembly according to claim 4, wherein the digital data wire comprises a fibre- optic wire.

6. The assembly according to claim 4 or claim 5, wherein the power wire is connected to a source relatively close to the assembly and remote from a normal inboard processing sonar room on a vessel.

7. The assembly according to any one of claims 1 to 6, wherein the processing module is held in place inside the housing using a resin.

8. The assembly according to any one of claims 1 to 7, wherein the housing further comprises EMC shielding.

9. The assembly according to any one of claims 1 to 8, wherein the processing module comprises circuitry to measure current and voltage associated with the transducer element while transmitting.

10. The assembly according to any one of claims 1 to 9, wherein the processing module comprises circuitry to perform impedance checking on the transducer element.

11. The assembly according to any one of claims 1 to 10, wherein the processing module comprises any one or more of an accelerometer, a gyroscope, and a magnetometer for obtaining additional information related to the assembly.

12. The assembly according to any one of claims 1 to 1 , wherein the transducer element is any one of: a conventional Tonpilz transducer, a flexural head Tonpilz transducer, and a double head mass Tonpilz transducer.

13. A sonar system comprising a plurality of transducer assemblies according to any one of claims 1 to 12, a switching box, a data processing module bus connecting the plurality of transducer assemblies to the switching box, and a connection to an operator console on a vessel for controlling the plurality of transducer assemblies.

14. The system according to claim 13, further comprising a computing device

communicably coupled to the tranducer assemblies via the connection, the computing device comprising a memory storing computer executable instructions for operating the plurality of transducers to perform one or more sonar applications.

15. The system accordiftg to claim 14, wherein the one or more sonar applications comprise any one or more of beam forming, beam steering, down sampling, and filtering operations.

16. A method for assembling an integrated sonar transceiver and transducer assembly, the method comprising: modifying a housing configured for an existing transducer element by reducing a portion thereof in size to provide additional room in the housing; removing a transformer from the housing; incorporating a software defined processing module included in the housing in place of the transformer, the processing module comprising a configurable electronics board providing a linear power amplifier and matching transformer; removing an existing connection from the transducer element; and providing a connection comprising data and power wires to communicate with and power the processing module to operate the transducer assembly.

17. The method according to claim 16, wherein reducing the portion of the transducer element comprises replacing a normally steel rear mass with a higher density material.

18. The method according to claim 16 or claim 17, wherein providing the connection comprises replacing a normal analog cable with a digital data wire and power wire.

19. The method according to claim 18, wherein the digital data wire comprises a fibre- optic wire.

20. The method according to claim 18 or claim 19, further comprising connecting the power wire to a source relatively close to the assembly and remote from a normal inboard processing sonar room on a vessel.

21. The method according to any one of claims 16 to 20, further comprising adding a resin to the housing to hold the processing module in place.

22. The method according to any one of claims 16 to 21 , further comprising adding EMC shielding to the housing.

23. The method according to any one of claims 16 to 22, further comprising incorporating in the processing module, circuitry to measure current and voltage associated with the transducer element while transmitting.

24. The method according to any one of claims 16 to 23, further comprising

incorporating, in the processing module, circuitry to perform impedance checking on the transducer element.

25. The method according to any one of claims 16 to 24, further comprising

incorporating, in the processing module, any one or more of an accelerometer, a gyroscope, and a magnetometer for obtaining additional information related to the assembly.

26. The method according to any one of claims 16 to 25, wherein the transducer element is any one of: a conventional Tonpilz transducer, a flexural head Tonpilz transducer, and a double head mass Tonpilz transducer.

27. An integrated sonar transceiver and transducer assembly, the assembly comprising: a first housing configured for an electro-acoustic transducer element, the transducer element comprising a transformer, and an active element; a second housing attached to an upper end of the first housing, the second housing being sized to contain a software defined processing module, the processing module comprising a configurable electronics board, the processing module being coupled to the transformer; and a connection comprising data and power wires to communicate with and power the processing module to operate the transducer assembly.

28. The assembly according to claim 27, wherein the processing module comprises a linear power amplifier and a matching transformer.

29. The assembly according to claim 27 or claim 28, wherein the transducer element is any one of: a conventional Tonpilz transducer, a flexural head Tonpilz transducer, and a double head mass Tonpilz transducer.