Acoustic device and method for amplifying interrogation signals and applying information - Patents.com

Abstract

A transponder (10) that provides information about itself upon receiving an acoustic interrogation signal. The transponder (10) includes a power source (20), an electronic circuit (30) connected to the power source (20), and one or more transducers (40) that receive the acoustic signal. The electronic circuit (30) includes a sequence generator (50) and an amplification and modulation unit (60) configured to modulate the received acoustic signal according to a sequence generated by the sequence generator (50), amplify the modulated signal, and then transmit the amplified, modulated signal through one or more transducers (40) and / or other transducers of the transponder (10).

Description

[Technical field]

[0001] The present invention relates to the technical field of acoustics, and more particularly to acoustic transponders that amplify and impress information on interrogation signals to provide unique identification and localization of underwater objects connected to the transponder. [Background technology]

[0002] A transponder is a device that transmits or reflects a distinguishable signal in response to a received interrogation signal. For underwater acoustic applications, there are two main types of transponders: active transponders and passive transponders.

[0003] A conventional active transponder receives an interrogation signal and activates a transmitter that transmits a signal in response to the interrogation signal. A passive transponder simply reflects the interrogation signal and provides little information other than the distance from the interrogation unit. An example of a passive transponder is described in US Pat. No. 5,399,633.

[0004] There are also semi-passive transponders, described in US Pat. No. 5,399,633. In this solution, the reflected signal is imbued with information by modifying the acoustic reflection coefficient of the transponder. The term semi-passive relates to the fact that a small battery is present to power a simple electronic circuit adapted to modify the acoustic reflection coefficient of the transducer. The returned signal is a reflection, but due to the variation of the reflection coefficient this signal has been modified. This type of transponder is suitable for detection at relatively short distances, since the reflected signal is not amplified. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] European Patent No. 1846917 [Patent Document 2] International Publication No. 2017 / 121752 Summary of the Invention [Problem to be solved by the invention]

[0006] An acoustic transponder according to the present invention does not have a full receiving unit to search for an interrogation signal, nor a full transmitter unit to transmit a stand-alone signal in response to the interrogation signal. [Means for solving the problem]

[0007] Instead, the transponder directly uses the incoming signal as the source of the outgoing signal, which is amplified and has information imposed on it before being sent back into the water.

[0008] The acoustic transponder includes an extraction filter that extracts the incoming interrogation signal from other signals, an amplifier that amplifies the interrogation signal, a modulation circuit that impresses information onto the amplified signal, and a suppression filter that suppresses the original interrogation signal while passing the information-impressed signal.

[0009] This configuration has several advantages for identification and localization applications. One advantage is that no synchronization is required for the interrogation signal, since it is passed without any delay other than that introduced by filters and other analog components. Accurate distance measurements can then be made on the central unit transmitting the interrogation signal by measuring the delay between the transmitted and received signals. Because the transponder uses the interrogation signal, it does not require accurate trigger circuits or clocks within the transponder itself. This means that no accurate oscillator is required to generate the acoustic wave center frequency.

[0010] This allows the Doppler velocity estimation, i.e. the estimation of the velocity along the communication path from the interrogation unit to the transponder, to be performed without relying on the accuracy of the electronics inside the transponder.

[0011] Another advantage is that different types of interrogation signals can be used.

[0012] One type of interrogation signal can be used to provide transponder identification as well as additional information, which reduces the probability of bit errors. Another type of interrogation signal can be used for high accuracy distance estimation. The signal chain and processing performed in the transponder can be the same for both types of interrogation signals.

[0013] The main advantage of the present invention over semi-passive transponders is the increased detection range due to the amplification of the signal within the transponder.

[0014] A transponder according to the invention can be made so as to be compatible with said semi-passive transponders: it can utilize the same types of interrogation signals and can impart information to the signals so that the receiver in the interrogation unit can use the same algorithms to interpret the signals from the semi-passive transponders as for the transponder according to the invention.

[0015] The main advantage of the present invention over the prior art is that the signal strength received at the interrogation unit is stronger due to the presence of an amplifier in the signal chain from the interrogation transmitter to the interrogation receiver.

[0016] A transponder according to the invention is particularly useful when the interrogation unit is integrated into a conventional echolocator or sonar.

[0017] The fact that the signal to noise ratio at the transponder input is typically very good is exploited to make a simple extraction filter unit, which still has good signal quality to apply information before and after amplification and before sending the signal back to the interrogation unit.

[0018] The present invention provides a good and versatile solution for several underwater applications. The outgoing acoustic signal from the transponder is amplified and this signal contains the identity of the transponder, making it suitable to be used for identifying objects over longer distances than the semi-passive transducers mentioned above. For example, by connecting the transponder of the present invention to different types of equipment, it is possible to find the identity and location of the transponder and thus the equipment to which it is connected. One application is the identification of lost cargo or fishing gear, which is known to be a global environmental problem. Another application is the use of the present invention to provide the exact location of e.g. trawl doors, longlines, seine nets during fishing. In general it is suitable for the positioning of e.g. anchoring devices, risers, pipes, etc.

[0019] Yet another application is the monitoring of underwater systems such as aquaculture nets. It is particularly important to continuously monitor the shape of such nets to prevent them from being carried away when exposed to strong winds or currents. For example, an alarm may be triggered if the shape of the net deviates from a predefined standard.

[0020] In addition to identifying and locating the transponder, additional information from sensors connected to the transponder can be imprinted on the signal. This provides several applications in which the availability of sensor data is of interest, whether or not it simultaneously provides identification and localization information.

[0021] The invention is set forth and characterized in the main claim, while the dependent claims describe further characteristics of the invention.

[0022] The present invention is defined by an acoustic transponder that provides information regarding the transponder upon receiving a recognizable acoustic interrogation signal.

[0023] The transponder comprises a power source, electronic circuitry connected to the power source, and an acoustic Interrogation and one or more transducers for receiving and transmitting signals.

[0024] The electronic circuit includes a sequence generator and an amplification and modulation unit, which amplifies the received acoustic signal according to a sequence generated by the sequence generator. Interrogation The transponder is configured to modulate a signal, amplify the modulated signal, and transmit the amplified modulated signal through one or more transducers of the transponder and / or through another transducer.

[0025] All of the above elements of the acoustic transponder are enclosed within a housing that is preferably waterproof.

[0026] acoustic Interrogation The transducer that receives the signal is, in one embodiment, also used to emit the amplified modulated signal. In this case, the acoustic transponder includes only one transducer. In another embodiment, an additional transducer is used to emit the amplified modulated signal. The additional transducer may be included within the housing of the acoustic transponder or may be included in another external device.

[0027] In one embodiment, the electronic circuit further comprises an extraction filter and a suppression filter, the extraction filter adapted to extract the acoustic interrogation signal received by the transducer and to suppress other signals before being input to the amplification and modulation unit, the suppression filter configured to suppress the received acoustic interrogation signal from the amplified modulated signal.

[0028] In one embodiment, the extraction filter comprises: Reception A bandpass filter adapted to suppress signals other than the acoustic interrogation signal.

[0029] In one embodiment, the extraction filter comprises: Reception A combination of high-pass and low-pass filters adapted to suppress signals other than the acoustic interrogation signal.

[0030] In one embodiment, the suppression filter is a band-stop filter adapted to pass the amplified modulated signal and suppress other signals.

[0031] In one embodiment, the suppression filter is a combination of a high-pass filter and a low-pass filter adapted to pass the amplified modulated signal and suppress other signals.

[0032] In one embodiment, the extraction filter and the suppression filter are combined into one filter unit.

[0033] In one embodiment, the amplification and modulation unit is connected to a trigger unit adapted to activate the amplification and modulation unit only when the transponder receives an acoustic interrogation signal input to the transponder.

[0034] In one embodiment, amplification Modulation Unit is adapted to amplify only signals above a defined amplitude level.

[0035] In one embodiment, the amplification and modulation unit is adapted to apply any kind of static and / or dynamic information to the received signal.

[0036] In one embodiment, the acoustic transponder includes one or more amplifiers in the signal chain.

[0037] In one embodiment, the acoustic transponder includes a directional coupler connected between the extraction filter and the suppression filter in the electronic circuitry and connecting the transducer to the extraction filter and the suppression filter.

[0038] In one embodiment, the extraction filter, the suppression filter, and the sequence generator are implemented in an electronic circuit. It is realized as a digital solution, which: an amplifier connected to the transducer and a first anti-aliasing filter and, First Anti-Aliasing Filter and an A / D converter connected to Digital Filtering Modulation Unit and,Digital Filtering Modulation Unit and a D / A converter connected to Second Anti-Aliasing Filter Including, , the second anti-aliasing filter is connected to the transducer and the first anti-aliasing filter.

[0039] The invention is further defined by a method for providing information about a transponder upon receiving an acoustic interrogation signal, said transponder comprising a power source, an electronic circuit connected to said power source, and said acoustic interrogation signal. Interrogation and one or more transducers for receiving the signal. Interrogation The signal is modulated according to a sequence generated by a sequence generator included in the electronic circuit, and the modulated signal is amplified in an amplifier-modulator unit included in the electronic circuit, which then transmits the amplified modulated signal via one or more transducers of the transponder and / or via another transducer.

[0040] According to one embodiment, amplification Modulation Unit Before being input to the Interrogation The signal is extracted and other signals are suppressed, and the received acoustic interrogation signal is suppressed from the amplified modulated signal by a suppression filter.

[0041] According to one embodiment, the same transducer is used to both receive and transmit the signal.

[0042] According to one embodiment, different transducers are used for receiving and emitting the signals.

[0043] According to one embodiment, the modulation is performed using amplitude modulation having two or more modulation states.

[0044] According to one embodiment, the modulation is performed using phase modulation having two or more modulation states.

[0045] According to one embodiment, the modulation is performed using quadrature amplitude modulation having four or more modulation states.

[0046] According to one embodiment, the modulation is: Amplification Modulation Unit This is done by varying the amplitude and / or phase of the amplified signal according to the information bits going into

[0047] According to one embodiment, the modulation uses amplitude modulation, Amplification Modulation Unit This is done by placing the amplifier / modulator unit in an active or idle state according to the information bits input to the amplifier / modulator unit.

[0048] According to one embodiment, modulation is provided by switching the input of the amplification modulation unit between two or more amplitude and / or phase shifted versions of the signal output from the extraction filter.

[0049] According to one embodiment, a trigger unit included in the electronic circuitry activates the amplification and modulation unit when an input signal exceeding a set threshold is received for a set minimum time.

[0050] According to one embodiment, a trigger unit included in the electronic circuit activates the amplification and modulation unit upon receiving an input signal according to a set signal.

[0051] According to one embodiment, the set signal is an input signal that exceeds a set threshold within a minimum time.

[0052] According to one embodiment, the set signal is an input signal that exceeds a set threshold level for a certain percentage of the time within a minimum period. According to one embodiment, a locally generated signal is fed to the amplification and modulation unit in addition to, or instead of, a signal extracted from a transducer included in the transponder.

[0053] In the following description, numerous specific details are introduced to provide a thorough understanding of embodiments of the claimed transponder and method for providing information related to a transponder. However, those skilled in the art will recognize that these embodiments can be practiced without one or more of the specific details, or with other components, systems, etc. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring aspects of the disclosed embodiments. [Brief description of the drawings]

[0054] [Figure 1] FIG. 2 shows the different modules included in an acoustic transponder. [Diagram 2] FIG. 2 is a block diagram of a basic transponder. [Diagram 3] FIG. 2 shows a block diagram of a transponder with a trigger unit for power. [Figure 4] FIG. 1 shows a block diagram of a transponder equipped with a sensor. [Diagram 5] FIG. 1 shows a block diagram of a transponder with a directional coupler. [Figure 6] 1 shows a block diagram of a transponder implemented as a digital solution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] Hereinafter, an acoustic transponder according to the present invention will be described in detail with reference to the drawings.

[0056] FIG. 1 illustrates an embodiment of the present invention including different modules included in an acoustic transponder 10 .

[0057] The transponder 10 comprises a power source 20, an electronic circuit 30 connected to the power source 20, and one or more transducers 40 for receiving acoustic signals. The electronic circuit 30 comprises at least a sequence generator 50 and an amplification and modulation unit 60.

[0058] 1, the electronic circuit 30 further comprises an extraction filter 32 and a suppression filter 34. The extraction filter 32 acts as an interrogation receiver, passing only recognizable signals.

[0059] When the acoustic transducer 40 receives acoustic energy, it converts this energy into electrical energy. The received acoustic signal from the transducer 40 is fed through an extraction filter 32, and then modulated and amplified by a sequence generator 50 and an amplification and modulation unit 60. The modulation is performed according to a sequence generated by the sequence generator 50.

[0060] The amplification and modulation unit 60 can be realized in different ways.

[0061] One implementation is an amplifier followed by a mixer. The signal from extraction filter 32 is first amplified and then input to a mixer that adds the sequence from sequence generator 50. Another implementation is a mixer followed by an amplifier. In this configuration, the sequence from sequence generator 50 is added to the signal from extraction filter 32 and then amplified. In yet another embodiment, amplifiers are provided both before and after the mixer.

[0062] Binary phase shift keying (BPSK) may be provided by inputting a sequence in the mixer alternating between the interrogation signal received from extraction filter 32 and an inverted version of this signal. Other types of modulation are possible, for example selecting between different phase shifted versions of the interrogation signal in the mixer.

[0063] Providing an enable control on the amplifier allows amplitude modulation (AM) of the signal.

[0064] The sequence generator 50 is a logic circuit that provides a bit stream that is applied to the interrogation acoustic signal to the Amplification and Modulation Unit 60. The logic may be implemented in custom logic, FPGA / CPLD, microcontroller, or a combination of these technologies. The generated sequence may include some known bits used by the interrogation receiver to search for the signal from the transducer, some predefined or programmed identification bits, and possibly some bits from the sensor (see FIG. 4) that change dynamically with the sensor data.

[0065] The amplified modulated signal is then forwarded through a suppression filter 34 and through one or more transducers 40 of the transponder 10. The amplified modulated signal may be provided through transducers other than the transducer 40 that receives the acoustic signal.

[0066] The extraction filter 32 is adapted to extract the received acoustic interrogation signal and suppress other signals before it is input to the amplification and modulation unit 60. The resulting output from the extraction filter 32 is the interrogation signal, possibly with small additive noise impairments.

[0067] The suppression filter 34 is adapted to pass the signal to which the information from the amplification and modulation unit 60 is applied, and further to suppress the original interrogation signal. This avoids a signal loop created by the extraction filter 32 and the amplification and modulation unit 60, with a loop gain greater than 1, which may lead to self-oscillation. The extraction filter 32 may be a passive filter or a combination of a passive filter and an active filter. An active filter section may be combined with an amplifier in the amplification and modulation unit 60.

[0068] 2 shows a simple block diagram of an embodiment of an acoustic transponder 10 according to the invention. The electronic circuit 30 comprises a sequence generator 50 connected to an amplification and modulation unit 60.

[0069] The signal from the sequence generator 50 is fed to an amplification and modulation unit 60. In this way, the acoustic signal received by the transducer 40 and extracted by the extraction filter 32 is modulated according to the sequence generated by the sequence generator 50. The modulated signal, which is the signal to which the information defined by the sequence is imprinted, is then sent through a suppression filter 34, which isolates the original interrogation signal by passing only the amplified modulated signal. The resulting signal is then sent to one or more transducers 40, which convert the signal into acoustic energy. In this configuration, the power supply 20 supplies power to all the components included in the electronic circuit 30. The transducers 40 may be the same ones that received the original interrogation signal, or they may be other transducers.

[0070] Figure 3 shows a diagram of a transponder of another embodiment of the invention. A trigger unit 70 is connected to the power supply 20. In a simple embodiment, the trigger may be a simple rectifier followed by a low pass filter and a comparator. The addition of the trigger unit 70 to the electronic circuit 30 allows to save power by only powering the amplification and modulation unit 60 when an interrogation signal is detected.

[0071] In one embodiment, the sequence generator 50 is also powered and activated only when an interrogation signal is present. By including the trigger unit 70, the acoustic transponder 10 can be placed in a sleep mode until awakened, thereby activating all circuitry when a specific interrogation signal is detected. In this manner, minimal power is received when the transponder is in an inactive state.

[0072] 4 shows yet another embodiment of the invention in which one or more sensors 80 are included. By connecting the sensors 80 to a sequence generator 50, the transponder 10 can communicate the sensor data by having the sequence generator 50 apply a bit stream of received sensor data to an interrogation signal that is amplified and modulated before being transmitted. Various types of sensors may be used to measure temperature, pressure, salinity, etc.

[0073] 5 shows a basic block diagram of an embodiment of acoustic transponder 10 that includes a directional coupler 36. Instead of wiring together the transducer 40, extraction filter 32 and suppression filter 34, a directional coupler (also called a hybrid) is used to reduce coupling between the transmit and receive signals.

[0074] FIG. 6 shows a diagram of a digital solution implementation of an acoustic transponder according to the invention.

[0075] In this implementation, the above-mentioned extraction and suppression filters and the modulator can be realized in the digital domain. In practice, there are amplifiers and filters before and after the A / D and D / A converters. The figure shows anti-aliasing filters before the A / D converter and after the D / A converter. These may be realized as low-pass or band-pass filters. By using band-pass filters, the signal can be undersampled to minimize the digital computation load.

Claims

1. 1. An acoustic transponder (10) for providing information about the transponder (10) upon receiving an acoustic interrogation signal, the transponder (10) comprising a power source (20), an electronic circuit (30) connected to the power source (20), and one or more transducers (40) for receiving and transmitting the acoustic interrogation signal, the electronic circuit (30) including a sequence generator (50); The electronic circuit (30) further comprises an amplification and modulation unit (60), an extraction filter (32) and a suppression filter (34), the extraction filter (32) adapted to extract the received acoustic interrogation signal and suppress other signals before being input to the amplification and modulation unit (60), the amplification and modulation unit (60) configured to modulate the received acoustic interrogation signal according to a sequence generated by the sequence generator (50) and amplify the modulated signal, the suppression filter (34) adapted to suppress the received acoustic interrogation signal from the amplified modulated signal, the amplified modulated signal being forwarded via one or more transducers (40) and / or other transducers of the transponder (10).

2. 2. The acoustic transponder (10) of claim 1, wherein the extraction filter (32) is a bandpass filter adapted to suppress signals other than the received acoustic interrogation signal.

3. 2. The acoustic transponder (10) of claim 1, wherein the extraction filter (32) is a combination high-pass and low-pass filter adapted to suppress signals other than the received acoustic interrogation signal.

4. 2. The acoustic transponder (10) of claim 1, wherein the suppression filter (34) is a band-reject filter adapted to pass the amplified modulated signal and suppress other signals.

5. 2. The acoustic transponder of claim 1, wherein the suppression filter is a combination high-pass and low-pass filter adapted to pass the amplified modulated signal and suppress other signals.

6. The acoustic transponder according to any one of claims 1 to 5, wherein the extraction filter (32) and the suppression filter (34) are combined into one filter unit.

7. 7. The acoustic transponder (10) according to any one of claims 1 to 6, wherein the amplification and modulation unit (60) is connected to a trigger unit (70) adapted to activate the amplification and modulation unit (60) only when the transponder (10) receives an acoustic interrogation signal input to the transponder (10).

8. The acoustic transponder (10) according to any of the preceding claims, wherein the amplification and modulation unit (60) is adapted to amplify only signals above a set amplitude level.

9. Acoustic transponder (10) according to any of the preceding claims, wherein the amplification and modulation unit (60) is adapted to impress any kind of static and / or dynamic information onto the transmitted signal.

10. The acoustic transponder (10) according to any of the preceding claims, wherein the acoustic transponder (10) comprises one or more amplifiers in the signal chain from the interrogation transmitter to the interrogation receiver.

11. 11. The acoustic transponder (10) according to claim 1, further comprising a directional coupler (36) connected between the extraction filter (32) and the suppression filter (34) in the electronic circuit (30) and connecting the transducer (40) to the extraction filter (32) and the suppression filter (34).

12. said extraction filter (32), said suppression filter (34) and said sequence generator (50) being realized as digital solutions in said electronic circuit (30); The digital solution includes an amplifier connected to the transducer, a first anti-aliasing filter, an A / D converter connected to the first anti-aliasing filter, a digital filtering and modulation unit connected to the A / D converter, a D / A converter connected to the digital filtering and modulation unit, and a second anti-aliasing filter connected to the D / A converter, The acoustic transponder (10) of any one of claims 1 to 11, wherein the second anti-aliasing filter is connected to the transducer (40) and to the first anti-aliasing filter.

13. 1. A method for providing information about a transponder (10) upon receiving an acoustic interrogation signal, the transponder (10) comprising a power source (20), electronic circuitry (30) connected to the power source (20), and one or more transducers (40) for receiving the acoustic interrogation signal; an extraction filter (32) for extracting the received acoustic interrogation signal and suppressing other signals before it is input to an amplification and modulation unit (60); modulating the received acoustic interrogation signal according to a sequence generated by a sequence generator (50) included in said electronic circuit (30) and amplifying the modulated signal in an amplifier-modulator unit (60) included in said electronic circuit (30); suppressing the received acoustic interrogation signal from the amplified modulated signal by a suppression filter (34); and transmitting the amplified modulated signal via one or more transducers (40) of the transponder (10) and / or via another transducer.

14. 14. The method of claim 13, wherein the same transducer is used for both receiving and transmitting the signal.

15. 14. The method of claim 13, further comprising using different transducers for receiving and transmitting the signals.

16. The method according to any of claims 13 to 15, wherein the modulation is performed using amplitude modulation having two or more modulation states.

17. The method according to any of claims 13 to 15, wherein the modulation is performed using a phase modulation having two or more modulation states.

18. The method according to any of claims 13 to 15, wherein the modulation is performed using quadrature amplitude modulation having four or more modulation states.

19. The method according to any of claims 13 to 15, wherein the modulation is performed by varying the amplitude and / or phase of the amplified signal according to information bits entering the amplification and modulation unit (60).

20. The method according to any one of claims 13 to 15, wherein the modulation is performed using amplitude modulation by putting the amplification and modulation unit (60) into an active or idle state depending on the information bits input to the amplification and modulation unit (60).

21. A method according to any of claims 13 to 20, wherein the modulation is provided by switching the input of the amplification and modulation unit (60) between two or more amplitude and / or phase shifted versions of the signal output from the extraction filter (32).

22. The method according to any one of claims 13 to 21, further comprising causing a trigger unit (70) included in the electronic circuit (30) to activate the amplification and modulation unit (60) when an input signal exceeding a set threshold is received for a set minimum time.

23. The method according to any of claims 13 to 21, wherein a trigger unit (70) included in the electronic circuit (30) activates the amplification and modulation unit (60) upon receiving an input signal according to a set signal.

24. 24. The method of claim 23, wherein the set signal is an input signal that exceeds a set threshold for a minimum amount of time.

25. 24. The method of claim 23, wherein the set signal is an input signal that exceeds a set threshold for a minimum percentage of time.

26. The method according to any of claims 13 to 25, further comprising feeding a locally generated signal to the amplification and modulation unit (60) in addition to or instead of the signal extracted from the transducer comprised in the transponder (10).

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