Description:FORM – 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
(SEE SECTION 10, RULE 13)

ACOUSTIC PINGER WITH INTEGRATED TRANSPONDER SYSTEM AND METHOD FOR DETECTION AND POSITIONING OF UNDERWATER VEHICLES

BHARAT ELECTRONICS LIMITED
HAVING ITS ADDRESS AT
OUTER RING ROAD, NAGAVARA,
BENGALURU (BANGALORE),
KARNATAKA-560045, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
TECHNICAL FIELD
[0001] The present invention relates generally to underwater positioning & recovery systems, and more particularly relates to a pinger system with an integrated transponder.
BACKGROUND
[0002] An underwater positioning system is a system for the tracking and navigation of underwater vehicles or divers by means of acoustic distance and/or direction measurements, and subsequent position triangulation. Underwater positioning systems are commonly used in a wide variety of underwater work, including oil and gas exploration, ocean sciences, salvage operations, marine archaeology, law enforcement and military activities. An underwater positioning system is realised as a sonar pinger system that has an emergency pinging system. Emergency pinger systems are underwater systems which are normally used for search and recovery applications. Typically, emergency pingers are fitted on an underwater vehicle such as a Remotely Operated Underwater Vehicle (ROV), Autonomous Underwater Vehicle (AUV), semi-submersible, or a large drilling vessel. A receiver to detect the pinger signal will be attached on the underwater vehicle or will be a handheld device for the diver. Pinger will get activated when it is underwater and when the power is lost. Pinger will contain a minimum of one transducer for transmitting the acoustic signal, which will mostly belong to a cylindrical or a directional type.
[0003] An underwater recovery system is used to recover underwater assets. Typically, an underwater transponder is used as a positioning system. Transponder systems are underwater systems which are normally used for aiding underwater positioning systems. These transponder systems will respond to a valid signal received from a surface transceiver device and transmit back a pulse, which will be captured by transceiver and used for position estimation. Typically, the transponder will have its own dedicated transducer, mostly directional type, and a dedicated hardware for coded pulse synthesis and transmission.
[0004] Patent US20070064525A1 discloses a system that provides a marine transponder comprising a position module, a satellite uplink module, and a microcontroller. The microcontroller being operable at intervals to activate the position module for providing a location reading and activate the satellite uplink module for transmission of the location reading and an identifying code.
[0005] Patent US5175708A discloses an acoustic transponder device which includes waterproof housing that accepts a battery pack with a water displacing connection, placing the housing and battery pack in communication. The housing carries an electronics package. Both the housing and battery pack can be disposable components and can be sealed upon manufacture to prevent water ingress.
[0006] Patent US7406001B1 discloses an underwater acoustic beacon comprising a cylindrical transducer and at least one spiral wavefront transducer aligned along a common central axis. For use in underwater navigation, the cylindrical and spiral wavefront transducers are activated individually and in combination in accordance with a prescribed sequence.
[0007] Patent US4156136A discloses a light activated acoustic pinger that is useful for underwater three-dimensional homing. The pinger includes a spherical lens system, a tone burst generator electronics system and a high-pressure watertight encasement. When a light source used by an underwater diver, submersible, underwater television system or navigator is panned on the pinger lens system in either the X or Y planes the ping rate will vary depending upon the incident angle of the light received by the spherical lens. In addition, moving the light toward the pinger in the Z direction will increase the ping rate. From the ping rate and the movement of the light source in the X, Y and Z directions an underwater navigator can determine the direction of the pinger and target. There is no battery drain until the pinger is activated by light and therefore targets that have been lost for several years may still be found based on battery shelf life.
[0008] Patent US3939463A discloses an acoustic obstacle detection and navigating system having a transmitting station comprising a variable frequency oscillator, a sawtooth generator coupled to said oscillator for sweeping the frequency of oscillations, a submersible projection transducer coupled to said oscillator, a sonar receiver at said station including a mixer, a remote transponder station including a receiving hydrophone coupled to a transmitting transducer, a mixer coupled between said hydrophone and transmitting transducer, a local oscillator of fixed frequency and a second receiver at said transmitting station including a mixer for combining signals repeated from said remote transponder with the frequencies, of said fixed frequency oscillator, and a common display for both mentioned receivers.
[0009] Traditional sonar pinger systems predominantly have only emergency pinging functionality. A transponder is realized as a separate system. This results in requirement of multiple complex hardware at the cost of increased expenditure as well as space requirements.
[0010] There is still a need for an invention which solves the above defined problems and provides an acoustic pinger with an integrated transponder system. More specifically, a device that can integrate pinger and transponder functionality into a single system using the same hardware. It is desirable that the device selects the operating mode based on water depth, external power input, and battery backup.
SUMMARY
[0011] This summary is provided to introduce concepts of the present invention. This summary is neither intended to identify essential features of the present invention nor is it intended for use in determining or limiting the scope of the present invention.
[0012] In accordance with the present invention, an acoustic pinger with integrated transponder system is disclosed. The acoustic pinger with integrated transponder system comprises a housing comprising: a battery; and an electronics card configured to operate the system to operate in either of a pinger operating mode or a transponder operating mode; a bottom end cap comprising: an integrated power and data input underwater connector; an external battery underwater connector to support an external battery; one or more underwater switches for configuring the system; a top end cap comprising: an acoustic transducer; a pressure sensor; a Light Emitting Diode; wherein the top end cap and the bottom end cap cover the two open ends of the housing.
[0013] In one aspect, the electronics card comprises: a battery management module, a regulator and a boost regulator configured to interface with integrated power and data input underwater connector and the external battery underwater connector to regulate voltage in the system; a pressure data convertor configured to receive sensed pressure measurements from the pressure sensor , convert the received pressure measurement to pressure data and calculate depth data from the pressure data; a serial communication port configured to provide interface with a base station; a Direct Digital Synthesis (DDS) Integrated Circuit to generate a pulse for transmission based on a received electrical pulse and a power amplifier to amplify the transmission pulse; a Transmit – Receive switch configured to transmit or receive electrical pulses based on an operating mode of the system; a preamplifier and a Band pass filter configured to filter a received signal; the microcontroller configured to receive filtered signal from the preamplifier and a Band pass filter and further configured to: check the depth data from the pressure data convertor; check the power received from the integrated power and data input underwater connector; operate the system on either of pinger operating mode or the transponder operating mode, and identify false alarms based on depth and power data.
[0014] In another aspect, the system in pinger operating mode is configured to: set a specific time for activating the pinger operating mode using serial communication; set a specific time interval for providing a transmission of a transmission pulse using serial communication; check at the microcontroller (310) the received depth data from the pressure data convertor; check at the microcontroller, the power received from the integrated power and data input underwater connector; and if no power signal is received at the battery management system from an external source, generate the transmission pulse at transmission Direct Digital Synthesis (DDS) Integrated Circuit and amplify the transmission pulse for transmission using a power amplifier at the specific time intervals, and activate the Light Emitting Diode (LED) for easy detection of the system.
[0015] In yet another aspect, the system in transponder operating mode is configured to: receive an acoustic signal from the acoustic transducer and transmit the received signal to the preamplifier and band pass filter; process the received signal at the preamplifier and the band pass filter and transmit the processed signal to the microcontroller; validate the processed signal as valid signal at the microcontroller by checking a pulse frequency and pulse count of the processed signal; generate a pulse for transmission at the Direct Digital Synthesis (DDS) Integrated Circuit and transmit the pulse, wherein the generated pulse can be set with a unique code to identify the deployed acoustic pinger with integrated transponder system; based on the depth data, the transmit pulse count and transmit pulse amplitude are varied.
[0016] In yet another aspect, the pinger mode further comprises: a Depth aided Pinger Mode (DPM), wherein the depth aided pinger mode (DPM) is activated based on depth data and when no power is received at the battery management system (304) from an external source. The Transponder Mode further comprises: a Depth aided Transponder Mode (DTM), wherein a depth data embedded pulse is generated at the Direct Digital Synthesis (DDS) Integrated Circuit along with the transmission pulse for transmission; a Repeated Depth Transmit Mode (RDTM) wherein a depth data embedded pulse is generated at the Direct Digital Synthesis (DDS) Integrated Circuit along with the transmission pulse for transmission at pre-defined intervals; and a Tethered Transponder Mode (TTM), wherein the acoustic pinger with integrated transponder system receives a command from a base station through a tether cable to operate in tethered Transponder Mode (TTM).
[0017] In yet another aspect, the transmission power and transmission power rate selection are performed based on depth data and the unique code is utilized to identify a specific acoustic pinger with integrated transponder system from a plurality of deployed acoustic pinger with integrated transponder systems.
[0018] In one aspect, based on the depth data and power data, the pulse width, number of bits and pulse amplitude are varied in a transmission pulse.
[0019] In accordance with the present invention, a method for detection and positioning of underwater vehicles using an acoustic pinger with integrated transponder system, the method comprising: deploying the acoustic pinger with integrated transponder system housed in an underwater vehicle in a waterbody;
receiving power status and depth data at the acoustic pinger with integrated transponder system; activating the acoustic pinger with integrated transponder system to function in either of: Pinger Mode (PM) or Transponder Mode (TM).
[0020] In one aspect, the acoustic pinger with integrated transponder system operating in the transponder mode (TM), comprises: receiving an acoustic signal; processing the received signal; validating the processed signal as valid signal by checking a pulse frequency and pulse count of the processed signal; generating a pulse for transmission and transmitting the pulse, wherein the generated pulse can be set with a unique code to identify the deployed acoustic pinger with integrated transponder system; wherein the acoustic pinger with integrated transponder system varies the transmit pulse count and transmit pulse amplitude based on depth data.
[0021] In one aspect, the acoustic pinger with integrated transponder system operating in the pinger mode (PM) comprises: setting a specific time for activating the pinger mode; setting a specific time interval for providing a transmission of a transmission pulse; checking the received depth data; checking, the power received; and if no power signal is received, generating the transmission pulse and amplifying the transmission pulse for transmission at the specific time intervals, and activating a Light Emitting Diode (LED) of the acoustic pinger with integrated transponder system for easy detection of the system.
[0022] In one aspect, the acoustic pinger with integrated transponder system operating in the Depth aided Pinger Mode (DPM), comprises: checking the received depth data and power data, and when no power is received, activating the depth aided Pinger mode.
[0023] In one aspect, the acoustic pinger with integrated transponder system operating in the Transponder Mode further comprises: generating and transmitting a depth data embedded pulse along with a transmission pulse in the Depth aided Transponder Mode (DTM); generating and transmitting a depth data embedded pulse along with a transmission pulse at predefined intervals in the repeated Depth aided Transponder Mode (DTM).
[0024] In one aspect, the acoustic pinger with integrated transponder system operating in the Transponder Mode further comprises: generating and transmitting a depth data embedded pulse along with a transmission pulse in the Depth aided Transponder Mode (DTM); generating and transmitting a depth data embedded pulse along with a transmission pulse at predefined intervals in the repeated Depth aided Transponder Mode (DTM).
[0025] In one aspect, selecting a transmission power and transmission power rate of a transmission pulse is based on depth data and the transmission pulse is varied by changing the pulse width, number of bits and pulse amplitude based on depth data and power data.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[0026] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference-like features and modules.
[0027] Figure 1 illustrates an operating environment in which the acoustic pinger with integrated transponder system works, according to an exemplary implementation of the present invention.
[0028] Figure 2 illustrates an embodiment of the acoustic pinger with integrated transponder system with end caps and a cylindrical enclosure, according to an exemplary implementation of the present invention.
[0029] Figure 3 illustrates a hardware architecture of pinger cum positioning system, according to an exemplary implementation of the present invention.
[0030] Figure 4A illustrates a flowchart showing the working methodology of automatic mode switching, according to an exemplary implementation of the present invention.
[0031] Figure 4B illustrates a flowchart showing the working methodology for interrupt service according to an exemplary implementation of the present invention.
[0032] Figure 4C illustrates a flowchart showing the working methodology of a transponder, according to an exemplary implementation of the present invention.
[0033] Figure 4D illustrates a flowchart showing the working methodology of a pinger, according to an exemplary implementation of the present invention.
[0034] Figure 4E illustrates a flowchart showing the idle state of acoustic pinger with integrated transponder system according to an exemplary implementation of the present invention.
[0035] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative methods embodying the principles of the present invention. Similarly, it will be appreciated that any flow charts, flow diagrams, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION
[0036] The various embodiments of the present invention describe a pinger system with an integrated transponder and a method for detection and positioning of underwater vehicles.
[0037] In the following description, for the purpose of explanation, specific details are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these details. One skilled in the art will recognize that embodiments of the present invention, some of which are described below, may be incorporated into a number of systems.
[0038] However, the systems and methods are not limited to the specific embodiments described herein. Further, structures and devices shown in the figures are illustrative of exemplary embodiments of the present invention and are meant to avoid obscuring of the present invention.
[0039] It should be noted that the description merely illustrates the principles of the present invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present invention. Furthermore, all examples recited herein are principally intended expressly to be only for explanatory purposes to help the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.
[0040] The invention provides a system and method which implements both pinger and transponder functionality into a single device using the same. The integrated pinger and transponder system that aids search and rescue teams to locate a submerged underwater vehicle like side scan sonar tow fish, AUV, ROV etc., by detecting the repeatedly emitted acoustic pulse. In addition, the integrated pinger and transponder system also has an inbuilt underwater positioning system which supports real time underwater position estimation for survey applications. The system can operate as emergency pinger at any depth and for any duration based on the enclosure & battery pack design. The duration can be extended by using external battery packs. Pinger functionality gets activated based on power cut off, and water activation.
[0041] In a preferred embodiment, a time offset setting to start pinger functionality is disclosed in the invention. In a preferred embodiment, the invention has a feature to activate pinger based on depth selected. The invention is hydrodynamically designed to support typical AUV, ROV and tethered tow fish operations and is capable of being deployed on underwater systems of any standard capacity.
[0042] In a preferred embodiment, the system can function in various modes of operations like Pinger Mode (PM), Depth aided Pinger Mode (DPM), Transponder Mode (TM), Depth aided Transponder Mode (DTM), Repeated Depth Transmit Mode (RDTM), Tethered Transponder Mode (TTM) and Idle (IM). In Pinger Mode (PM), when power is lost, the system will start pinging. In Depth aided Pinger Mode (DPM), the system will check pressure reading in addition to power loss, to ensure minimum depth to activate pinger. In Transponder Mode (TM), the system operates as a typical transponder which responds to transceiver signal. In Depth aided Transponder Mode (DTM), the system transmits depth information embedded pulse along with header pulse. In Repeated Depth Transmit Mode (RDTM), the system repeatedly transmits depth information embedded pulse along with header pulse without waiting for transceiver signal. In Tethered Transponder Mode (TTM), the transponder of the system is triggered through the data port instead of the transceiver signal. The functional operation is independent of an underwater vehicle on which the system is mounted.
[0043] Figure-1 illustrates an operating environment in which the acoustic pinger with integrated transponder works. The operating environment shows a surface platform,102, that is communicating to an underwater vehicle, 104, via a tow cable (tether),105, in water,101. The underwater vehicle,104, is equipped with a pinger cum transponder,107, (herein after transponder 107) that transmits and receives signals from the transceiver,103, which is attached at the bottom of the towing platform,102. The transponder 107, has the capability of operating in pinger mode using the inbuilt battery pack. The transmission and reception of acoustic signal is a line of sight 106 operations. The transponder107, triggering is performed through the tether 105 if required. In another embodiment, the transponder 107 is activated by the transceiver, 103, by transmitting the activating pulses to the transponder.
[0044] Figure-2 illustrates a transponder, 107 housed in an enclosure. The system consists of a submersible housing (enclosure) configured to be coupled to and disposed at least partially or completely outside an underwater vehicle. The enclosure comprises of a body in a cylindrical shape along with end caps. A cylindrical enclosure 208 houses all the components of the transponder 107. A bottom end cap 201 and a top end cap 202 are fixed on the bottom and top end of the cylindrical enclosure. The end caps ensures that the enclosure is sealed and prevents water ingress. The cylindrical enclosure 208 contains a battery, 209, and an electronics card, 210. The Bottom endcap, 201, is equipped with an integrated power & data input underwater connector, 203, an external battery underwater connector, 211, and an underwater switch, 204. The Top endcap, 202, is equipped with an acoustic transducer, 207, a pressure sensor, 206 and a Light Emitting Diode, 205. The Bottom and Top Endcaps are covered with both radial & face O-rings for sealing. In a preferred embodiment, the transponder system may be implemented on any underwater enclosure of any shape, but all the components indicated above must be housed and supported in a watertight environment. In preferred embodiment, the battery pack is shaped to fit into the housing and an electronics tray defining an attachment for forming an electrical connection between the battery pack, the electronics package and pressure sensor. Furthermore, a pair of external battery terminals on the end cap; a pair of connector pins on the battery that can register and connect to the external battery; an acoustic element for transponder or pinger in an underwater environment; lights & external switches on end cap, and underwater connectors for power & data communication inputs are also preferred.
[0045] Figure-3 illustrates the hardware architecture of acoustic pinger with integrated transponder system. As shown in Figure 3, the connection diagram between major components within the system. The battery 209 is connected to an integrated power and data input underwater connector 203 that provides the power input and regulators generate all internal voltages. A Battery management system 304 controls charging and discharging of the battery 209 and manages the power source switching. The external battery underwater connector, 211 also supports the external battery. A serial communication port 303 is present along with other components to receive/send specific data/commands via a tether cable 105 to the base station. In a preferred embodiment, a Universal Asynchronous Receiver Transmitter (UART) port is used as a serial communication port.
[0046] A micro-controller 310 is used to implement the pinger-transponder functionality. In a preferred embodiment, the functions performed by the microcontroller 310 can be realised either using a field programmable gate array (FGPA) or a microprocessor. A Direct Digital Synthesis (DDS) IC 311 is used to generate the transmit pulse is amplified using the power amplifier and fed into the transducer, 207. A transmitter receiver switch prevents the high voltage transmit pulse entering input section. When an acoustic pulse is transmitted to the acoustic transducer 207, the transmitter receiver switch 309 is activated, and it passes through preamplifier and band-pass filter sections 308. The valid incoming signal generate square pulses using a comparator and it is fed into the microcontroller 310. The microcontroller 310 implements a false alarm detection algorithm and checks if a valid pulse is received or not. On the reception of a valid pulse, the microcontroller 310 responds with a pulse transmission. The microcontroller continuously checks the pressure, 206 and power input, 203, status and decides on which operating mode to activate. The data input option, 203 aids in system configurations, firmware update, tethered transponder triggering and status notification. The underwater switch, 204 helps in activating the device before deployment. In a preferred embodiment, the underwater switch 204 is implemented using a Double Pole Single Throw switch.
[0047] In a preferred embodiment, the acoustic pinger with integrated transponder can be set with a specific pulse code via the serial communication 303.
[0048] In a preferred embodiment, the acoustic pinger with integrated transponder wherein the acoustic pinger with integrated transponder selects transmit power is based on depth, where the system detects depth based on the pressure sensor measurement.
[0049] In a preferred embodiment, an acoustic pinger with integrated transponder system is allocated a unique code that the acoustic pinger with integrated transponder system can transmit in pinger or the transponder mode. Such a unique code may be set up before deployment of the acoustic pinger with integrated transponder system. In one embodiment, pinger mode, it may transmit one unique code and in transponder mode it may transmit another unique code or have a specific unique code for transmission. If more than one acoustic pinger with integrated transponder systems are deployed, then each of these devices can be identified uniquely with the unique code received.
[0050] In a preferred embodiment, an adaptive pulse coding scheme based on the depth information obtained through pressure sensor, based on positioning resolution (set at the time of deployment) and on the availability of external power, transmit pulse characteristics will be modified automatically to perform the adaptive pulse coding scheme. In a preferred embodiment, the pulse width of pulse code, number of bits in pulse code, pulse amplitude, etc will vary based on the above parameters.
[0051] The manner in which the acoustic pinger with integrated transponder system is activated and used is explained with respect to the flowcharts FIGs.4A-4E below.
[0052] In a preferred embodiment, the acoustic pinger with integrated transponder system (hereinafter the device) implements emergency pinger cum transponder operation. This aids in search, rescue as well as positioning applications. The device implements depth, water & power loss activated pinger functionality. The device implements a remote device configuration or activation through data port. The device implements signal pulse detection and frequency-based triggering for transponder. The device aids in multiple device identification using pulse coding technique. The device incorporates a tethered triggering option through data ports. The device implements depth based auto transmit power selection. The device implements time offset adjustments for pinger mode activation. The device incorporates multi-positioning algorithm supports like normal transponder operation, transponder with depth embedded pulse transmission, and repeated depth embedded pulse transmission. The device implements depth aided repetition rate selection. The device implements adaptive pulse coding schemes for position estimation based on range. The device incorporates external battery connection to extend duration of pinger operation. In a preferred embodiment, the device incorporates light activation in pinger mode for easy detection. The device incorporates external switches to configure settings at the time of deployment.
[0053] Figure-4A shows an overview of the automatic mode switching method with respect to the acoustic pinger with integrated transponder system. At step 401, at the time of deployment, the enclosure is turned ON using switch, 204, and initialization process will be completed. During the initialization process of the acoustic pinger with integrated transponder system, default operating modes will be set. Pinger Mode (PM), Depth aided Pinger Mode (DPM), Transponder Mode (TM), Depth aided Transponder Mode (DTM), Repeated Depth Transmit Mode (RDTM), Tethered Transponder Mode (TTM) and Idle (IM) are the available modes. The pulse code to be transmitted is fixed during this process. The pinger activation depth details are fixed at this stage. All parameters initiated can be changed during runtime through data communication option. Then system checks for the power input and pressure sensor status, 402. Based on the readings, it will enter one of the system modes 403, 404, or 405 which is explained with respect to flow charts 4C-4E below.
[0054] Figure-4B illustrates the interrupt trigger flowchart, wherein an interrupt is triggered based on power input and pressure sensor status. At step 601, when the system is turned on using switch 204, acoustic pinger with integrated transponder system (hereinafter the “device”) enters an idle state, where all the default settings are initialized. At step 602, the interrupt service routine is initialised to detect power transition. At step 603, simultaneously, a timer is initiated, implementing a time out for checking to avoid dead loops. At step 604, until the timer times out, the device waits for the power transition event to happen. At step 604 if the power transition event happens, the device is placed at voltage state, 604, wherein the device checks the current voltage state of the external input. If the measured voltage is above a threshold, the device resets the power flag, otherwise it sets the power flag. At step 605, the device senses pressure sensor data. If pressure data read is above a threshold, then pressure flag will be set, otherwise it will be reset. At step 603, in case of time out, instead of waiting for a power transition, the device transitions to either of step 604 or step 605 to detect present voltage and pressure; assign flags accordingly and return to idle state at step 601.
[0055] Figure 4C illustrates the manner in which the transponder of the acoustic pinger with integrated transponder system (hereinafter the device) is activated. The transponder is activated when the device is underwater with a power source. The transponder activation corresponds to step 403 of Figure 4A. Typically, when the device is in pinger mode, the device waits for a trigger to enter the transponder mode. If a trigger is received, the trigger is validated for false alarms. If the trigger is a valid trigger, then the transponder transmits pulses as per initial settings. Then as per the flags, the device checks for the flags assigned by the interrupt routine. Based on the flags, the device waits for the next trigger. In a preferred embodiment, in Repeated Depth Transmit Mode (RDTM), Tethered Transponder Mode (TTM), no trigger and/or false alarm checks are performed.
[0056] Figure 4D illustrates the manner in which the pinger of the acoustic pinger with integrated transponder system (hereinafter the device) is activated. The pinger is activated when the device is underwater without power. The pinger activation corresponds to step 404 of Figure 4A. Once the device enters pinger mode, the device transmits a pulse based on the initial settings. Then the device checks the value of flags assigned by the interrupt routine, and the device enters next mode or continues in the same state.
[0057] Figure 4E illustrates the manner in which the acoustic pinger with integrated transponder system (hereinafter the device) is in idle state. Typically, the idle state is activated when the device is on surface. Once the device enters idle mode, the device checks the value of flags assigned by the interrupt routine. Based on the flags, the device enters the next stage or stays in the same stage.
[0058] In a preferred embodiment, the acoustic pinger with integrated transponder system is connected to a base station via a tow cable (tether) 105. The tow cable (105) interfaces with a serial communication port 303 for sending/receiving data. The base station may trigger the acoustic pinger with integrated transponder system to work in a transponder mode based on a command from the base station via the serial communication port 303. The acoustic pinger with integrated transponder system works as a transponder and performs the actions as described in Figure 4C.
[0059] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the invention.
, Claims:
1. An acoustic pinger with integrated transponder system, comprising:
a housing (208) comprising:
a battery (209); and
an electronics card (210) configured to operate the system to operate in either of a pinger operating mode or a transponder operating mode;
a bottom end cap (201) comprising:
an integrated power and data input underwater connector (203);
an external battery underwater connector (211) to support an external battery;
one or more underwater switches (204) for configuring the system;
a top end cap (202) comprising:
an acoustic transducer (207);
a pressure sensor (206);
a Light Emitting Diode (205);
wherein the top end cap and the bottom end cap cover the two open ends of the housing.

2. The acoustic pinger with integrated transponder system as claimed in claim 1, wherein the electronics card (210,301) comprises:
a battery management module (304), a regulator (305) and a boost regulator (307) configured to interface with integrated power and data input underwater connector (203) and the external battery underwater connector (211) to regulate voltage in the system;
a pressure data convertor (302) configured to receive sensed pressure measurements from the pressure sensor (206), convert the received pressure measurement to pressure data and calculate depth data from the pressure data;
a serial communication port (303) configured to provide interface with a base station;
a Direct Digital Synthesis (DDS) Integrated Circuit (311) to generate a pulse for transmission based on a received electrical pulse and a power amplifier (312) to amplify the transmission pulse;
a Transmit – Receive switch (309) configured to transmit or receive electrical pulses based on an operating mode of the system;
a preamplifier and a Band pass filter (308) configured to filter a received signal;
a microcontroller (310) configured to receive filtered signal from the preamplifier and a Band pass filter (308) and further configured to:
check the depth data from the pressure data convertor (302);
check the power received from the integrated power and data input underwater connector (203);
operate the system on either of pinger operating mode or the transponder operating mode, and
identify false alarms based on depth and power data.

3. The acoustic pinger with integrated transponder system as claimed in claim 2, wherein in transponder operating mode is configured to:
receive an acoustic signal from the acoustic transducer (207) and transmit the received signal to the preamplifier and band pass filter (308);
process the received signal at the preamplifier and the band pass filter and transmit the processed signal to the microcontroller (310);
validate the processed signal as valid signal at the microcontroller (310) by checking a pulse frequency and pulse count of the processed signal;
generate a pulse for transmission at the Direct Digital Synthesis (DDS) Integrated Circuit (311) and transmit the pulse, wherein the generated pulse can be set with a unique code to identify the deployed acoustic pinger with integrated transponder system;
based on the depth data, the transmit pulse count and transmit pulse amplitude are varied.

4. The acoustic pinger with integrated transponder system as claimed in claim 2, wherein the system in pinger operating mode is configured to:
set a specific time for activating the pinger operating mode using serial communication (303);
set a specific time interval for providing a transmission of a transmission pulse using serial communication (303);
check at the microcontroller (310) the received depth data from the pressure data convertor (302);
check at the microcontroller (310), the power received from the integrated power and data input underwater connector (203); and
if no power signal is received at the battery management system (304) from an external source,
generate the transmission pulse at transmission Direct Digital Synthesis (DDS) Integrated Circuit (311) and amplify the transmission pulse for transmission using a power amplifier (311) at the specific time intervals, and
activate the Light Emitting Diode (LED) for easy detection of the system.

5. The acoustic pinger with integrated transponder system as claimed in claim 1, wherein
the pinger mode further comprises:
a Depth aided Pinger Mode (DPM), wherein the depth aided pinger mode (DPM) is activated based on depth data and when no power is received at the battery management system (304) from an external source; and
the Transponder Mode further comprises:
a Depth aided Transponder Mode (DTM), wherein a depth data embedded pulse is generated at the Direct Digital Synthesis (DDS) Integrated Circuit (311) along with the transmission pulse for transmission;
a Repeated Depth Transmit Mode (RDTM) wherein a depth data embedded pulse is generated at the Direct Digital Synthesis (DDS) Integrated Circuit (311) along with the transmission pulse for transmission at pre-defined intervals; and
a Tethered Transponder Mode (TTM), wherein the acoustic pinger with integrated transponder system receives a command from a base station through a tether cable (105) to operate in tethered Transponder Mode (TTM).

6. The acoustic pinger with integrated transponder system as claimed in claims 4 and 5, wherein the transmission power and transmission power rate selection are performed based on depth data.

7. The acoustic pinger with integrated transponder system as claimed in claim 3, wherein the unique code is utilized to identify a specific acoustic pinger with integrated transponder system from a plurality of deployed acoustic pinger with integrated transponder systems.

8. The acoustic pinger with integrated transponder system as claimed in claim 3, wherein based on the depth data and power data, the pulse width, number of bits and pulse amplitude are varied in a transmission pulse.

9. A method for detection and positioning of underwater vehicles using an acoustic pinger with integrated transponder system, the method comprising:
deploying (401) the acoustic pinger with integrated transponder system housed in an underwater vehicle in a waterbody;
receiving (402) power status and depth data at the acoustic pinger with integrated transponder system;
activating (403,404) the acoustic pinger with integrated transponder system to function in either of: Pinger Mode (PM) or Transponder Mode (TM).

10. The method as claimed in claim 9, wherein the acoustic pinger with integrated transponder system operating in the transponder mode (TM), comprises:
receiving an acoustic signal;
processing the received signal;
validating the processed signal as valid signal by checking a pulse frequency and pulse count of the processed signal;
generating a pulse for transmission and transmitting the pulse, wherein the generated pulse can be set with a unique code to identify the deployed acoustic pinger with integrated transponder system;
wherein the acoustic pinger with integrated transponder system varies the transmit pulse count and transmit pulse amplitude based on depth data.

11. The method as claimed in claim 9, wherein the acoustic pinger with integrated transponder system operating in the pinger mode (PM) comprises:
setting a specific time for activating the pinger mode;
setting a specific time interval for providing a transmission of a transmission pulse;
checking the received depth data;
checking, the power received; and
if no power signal is received,
generating the transmission pulse and amplifying the transmission pulse for transmission at the specific time intervals, and
activating a Light Emitting Diode (LED) of the acoustic pinger with integrated transponder system for easy detection of the system.

12. The method as claimed in claim 9, wherein the acoustic pinger with integrated transponder system operating in the Depth aided Pinger Mode (DPM), comprises:
checking the received depth data and power data, and when no power is received, activating the depth aided Pinger mode.

13. The method as claimed in claim 9, wherein the acoustic pinger with integrated transponder system operating in the Transponder Mode further comprises:
generating and transmitting a depth data embedded pulse along with a transmission pulse in the Depth aided Transponder Mode (DTM);
generating and transmitting a depth data embedded pulse along with a transmission pulse at predefined intervals in the repeated Depth aided Transponder Mode (DTM).

14. The method as claimed in claims 10 and 11, wherein selecting a transmission power and transmission power rate of a transmission pulse is based on depth data.

15. The method as claimed in claims 10 and 11, wherein the transmission pulse is varied by changing the pulse width, number of bits and pulse amplitude based on depth data and power data.