Measuring hydrophone channel impedance

Abstract

Systems, devices, and methods for measuring hydrophone impedance are provided herein. A sensor may convert sound waves received via a liquid medium into electrical signals. A signal encoder (402) is coupled to the sensor (300) to receive the electrical signal. A test signal generator (406) is coupled in series with the sensor and the signal encoder and may generate a test signal. The test signal may measure the impedance of the sensor. A switch component (410) is coupled in series with the sensor, the signal encoder, and the test signal generator. The switch component may route the test signal to a first terminal of the sensor and through a second terminal of the sensor during a first operating state. The switch component may route the test signal to a second terminal of the sensor and through a first terminal of the sensor during a second operating state.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of and priority to U.S. Patent Application No. 16 / 707,410, filed on December 9, 2019, which is incorporated herein by reference in its entirety. Background Art

[0003] Electrical impedance measures the amount of resistance to the flow of electric current caused by a circuit or component. Measuring electrical impedance can be used to estimate the performance of a circuit or component. Summary of the invention

[0004] At least one aspect of the present disclosure relates to a system for measuring hydrophone impedance. The system may include a sensor that converts an acoustic wave received via a liquid medium into an electrical signal. The sensor may have a first polarity terminal and a second polarity terminal, the second polarity terminal having a polarity opposite to the first polarity terminal. The system may include a signal encoder that is coupled to the sensor to receive the electrical signal converted by the sensor. The system may include a test signal generator that is coupled in series with the sensor and the signal encoder to generate a test signal to be sent through the sensor and the signal encoder. The test signal may measure the impedance of the sensor. The system may include a switch component that is coupled in series with the sensor, the signal encoder, and the test signal generator. The switch component may have a first operating state and a second operating state. In response to the switch component being set to the first operating state, the switch component may route the test signal from the test signal generator to the first polarity terminal of the sensor, through the second polarity terminal of the sensor, and to the signal encoder. In response to the switch component being set to the second operating state, the switch component may route the test signal from the test signal generator to the second polarity terminal of the sensor, through the first polarity terminal of the sensor, and to the signal encoder.

[0005] At least one aspect of the present disclosure relates to a method for measuring the impedance of a hydrophone. The method may include generating, by a test signal generator, a test signal to be sent through a sensor and a signal encoder to measure the impedance of the sensor. The sensor may convert an acoustic wave into an electrical signal. The sensor may have a first polarity terminal and a second polarity terminal, the second polarity terminal having a polarity opposite to the first polarity terminal. The signal encoder may be connected in series with the sensor to receive the electrical signal. The method may include: in response to a switch component being set to a first operating state, a switch component connected in series with the sensor, the signal encoder and the test signal generator routes the test signal from the test signal generator to the first polarity terminal of the sensor, through the second polarity terminal of the sensor and to the signal encoder. The method may include: in response to the switch component being set to a second operating state, the switch component routes the test signal from the test signal generator to the second polarity terminal of the sensor, through the first polarity terminal of the sensor and to the signal encoder.

[0006] At least one aspect of the present disclosure relates to a device for measuring hydrophone impedance. The device may include a housing. The device may include a hydrophone channel disposed in the housing. The hydrophone channel may include a sensor that converts sound waves received via a liquid medium into an electrical signal. The hydrophone channel may include an input channel coupled to a signal encoder. The input channel may be coupled in parallel with the sensor to receive an electrical signal from the sensor. The hydrophone channel may include an input filter network that is coupled in series between the sensor and the signal encoder to transmit the electrical signal received from the sensor to the signal encoder. The device may include a test signal generator disposed in the housing. The test signal generator may be coupled in series with the hydrophone channel between the sensor and the input filter network. The test signal generator may generate a test signal to be sent through the hydrophone channel. The test signal may measure the impedance of the sensor. The device may include a switch component disposed in the housing. The switch component may be coupled in series between the sensor of the hydrophone channel and the signal encoder. The switch component may have a first operating state and a second operating state. The switch component may route a test signal from the test signal generator through the hydrophone channel in a first path in response to the switch component being set to the first operating state. The switch member may route the test signal from the test signal generator through the hydrophone channel in a second path in response to the switch member being set to the second operating state.

[0007] At least one aspect of the present disclosure is a method of providing an electronic circuit for measuring a hydrophone. The method may include providing an electronic circuit disposed in a housing. The electronic circuit may include a hydrophone channel. The hydrophone channel may include a sensor that converts an acoustic wave received via a liquid medium into an electrical signal. The hydrophone channel may include an input channel coupled to a signal encoder. The input channel may be coupled in parallel with the sensor to receive an electrical signal from the sensor. The hydrophone channel may include an input filter network coupled between the sensor and the signal encoder to transmit the electrical signal received from the sensor to the signal encoder. The electronic circuit may include a test signal generator coupled in series with the hydrophone channel between the sensor and the input filter network. The test signal generator may generate a test signal to be sent through the hydrophone channel. The test signal may measure an impedance of the sensor. The electronic circuit may include a switch component coupled in series between the sensor and the signal encoder of the hydrophone channel. The switch component may have a first operating state and a second operating state. The switch component may route a test signal from the test signal generator through the hydrophone channel in a first path in response to the switch component being set to the first operating state. The switch member may route the test signal from the test signal generator through the hydrophone channel in a second path in response to the switch member being set to the second operating state.

[0008] These and other aspects and embodiments are discussed in detail below. The above information and the following detailed description include illustrative examples of the various aspects and embodiments, and provide an overview or framework for understanding the nature and character of the claimed aspects and embodiments. The accompanying drawings provide illustration and further understanding of the various aspects and embodiments, and are incorporated into and constitute a part of this specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings are not intended to be drawn to scale. Like reference numerals and designations in the various drawings indicate like elements.

[0010] For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

[0011] Figure 1 An isometric view of an example environment depicting seismic operations in deep water;

[0012] Figure 2 depicts an isometric view of an example apparatus for acquiring seismic data;

[0013] Figure 3 A circuit diagram of an example sensor for converting acoustic waves propagating through a liquid into electrical signals is depicted;

[0014] Figure 4depicts a circuit diagram of an example system for measuring hydrophone impedance;

[0015] Figure 5 depicts a circuit diagram of an example system for measuring hydrophone impedance in a first operating mode;

[0016] Figure 6 depicts a circuit diagram of an example system for measuring hydrophone impedance in a second operating mode;

[0017] Figure 7 A graph depicting the input magnitude response of the hydrophone channel under simulated conditions;

[0018] Figure 8 Plotted is a graph of the input signal versus the leakage resistance of the hydrophone channel under simulated conditions;

[0019] Fig. 9 The relationship between the input signal frequency and the leakage resistance of the hydrophone channel under simulation conditions is depicted;

[0020] Fig.10 The relationship between the input signal and the impedance of the hydrophone channel under simulated conditions is depicted;

[0021] Fig.11 The relationship between the input signal and the impedance of the hydrophone channel under simulated conditions is depicted;

[0022] Fig.12 A flow chart depicting an example method of measuring hydrophone impedance;

[0023] Fig.13 A flow chart depicting an example method of providing an apparatus for measuring hydrophone impedance; and

[0024] Fig.14 Depicted is a block diagram of the architecture of a computing system for implementing the various elements of the systems and methods described herein. DETAILED DESCRIPTION

[0025] Various concepts and embodiments related to systems, devices, electronic circuits and methods for measuring hydrophone impedance are described in more detail below.The various concepts introduced above and discussed in more detail below can be implemented in many ways.

[0026] In an underwater seismic data acquisition system, a series of seismic data acquisition units (also referred to herein as nodes) can be deployed from a ship onto the seabed (which may include a lakebed). Each node can acquire seismic data related to underground features such as lithologic formations or fluid layers associated with the presence of hydrocarbons, minerals, or other elements. When acquiring seismic data, an acoustic signal can be emitted from a source (e.g., an air gun array) through a water column to propagate through the water and through the seabed and into the underground. The acoustic signal can be reflected or refracted from various underground features back to the earth's surface.

[0027] Nodes arranged along the surface can receive the returned acoustic signals and generate seismic readings from the acquired signals to detect whether there are lithological formations under the surface. In order to acquire the acoustic signals, each node can be equipped with one or more hydrophones such as piezoelectric sensors. The receiving end of the hydrophone can be in contact with or mechanically connected to the water, and can have an impedance that matches the acoustic impedance of the water to receive the incoming sound waves. Each hydrophone can be part of a hydrophone channel, which can include other circuits and components (e.g., input filters). The hydrophone can convert the water pressure changes caused by the incoming sound waves into electrical signals for transmission to the rest of the channel. The signal encoder within the node can be connected in parallel with the hydrophone channel and can receive the converted electrical signal from the hydrophone to convert the electrical signal into a digitized data sequence. Additional processing hardware connected to the signal encoder and the hydrophone channel can use the data from the hydrophone channel to generate seismic data and perform various other functions.

[0028] Over time and use, the performance of the hydrophones in the nodes may degrade, causing the readings of the seismic data produced by the nodes to degrade or fail to produce any useful data. For example, the wiring within the hydrophone may have become disconnected, causing the impedance of the hydrophone to deviate from the expected amount. The ceramic end caps of the hydrophone that are in contact with the water may eventually crack with repeated application of the acoustic signal, resulting in the inability to convert the acoustic signal into an electrical signal. In some cases, the hydrophone may have weak or poor performance from the outset due to manufacturing defects in the hydrophone or other components of the hydrophone channel.

[0029] Finding the cause of degradation or weakening of the performance of a node's hydrophone may be difficult. On the one hand, many hydrophones may have physical defects that are not easily discernible, such as shorts or opens within the hydrophone channel. On the other hand, some hydrophones may have a high dissipation factor (e.g., greater than 0.006) or a large leakage resistance (e.g., the leakage resistance is greater than 0.1 μA when 27 volts DC is applied before the hydrophone is installed in the node). A dissipation factor greater than 0.006 may indicate hydrophone degradation. Even in hydrophones with high dissipation factors or leakage resistances, detrimental operating characteristics may be apparent when measured using a test current of a specific frequency (e.g., 0 Hz to 50 Hz).

[0030] The performance of a hydrophone may be estimated by measuring the electrical impedance of the hydrophone. The electrical impedance of the hydrophone may correspond to the amount of resistance faced by a current flowing through the hydrophone and may be measured in ohms (Ω). A method for measuring the impedance of a hydrophone may include connecting a test signal generator circuit in parallel with a hydrophone channel. The test signal generator may generate a test signal for measuring the impedance of the hydrophone. The test signal generator may transmit the test signal to propagate through one of the terminals of the hydrophone and through the rest of the hydrophone channel to a signal encoder. The output signal from the hydrophone channel and the input test signal at the signal encoder may be used to measure the impedance.

[0031] One problem caused by the parallel configuration of the test signal generator can include the introduction of additional impedance into the hydrophone channel. With this configuration, the input channel of the signal encoder can be used as a voltage divider between the test signal generator and the parallel combination of the hydrophone and the hydrophone channel. The impedance introduced by the test signal generator can range from approximately 250Ω to 350Ω, while the parallel combination of the hydrophone and the channel can be approximately 10 6 Ω(1MΩ). Increasing the impedance and the parallel configuration may result in lower sensitivity in measuring the hydrophone impedance using the test signal. For example, when the leakage resistance reaches above 100kΩ, the change in the impedance of the hydrophone can be easily detected using a test signal with a frequency of 31.52Hz. Below this resistance value, the change in the impedance of the hydrophone may not be found.

[0032] In addition, for the parallel input configuration, the signal input to the channel can be the result of the test signal input and the voltage divider formed by the test signal generator output impedance and the channel input impedance. When the channel input impedance is 1MΩ and the test signal generator output impedance is 1kΩ, a 90% reduction in input impedance (from 1MΩ to 100kΩ) may result in a channel voltage input change of less than 1%. This provides poor measurement resolution in the region where the hydrophone impedance transitions from within specification to outside specification. The parallel configuration of the test circuit with the hydrophone channel may therefore result in an inability to distinguish different degradation levels in the hydrophone. In this way, it can be inferred at a later point in the life cycle of the node whether the performance of the hydrophone is degrading.

[0033] In order to more precisely and accurately measure the hydrophone impedance, the test signal generator can be connected in series with the hydrophone channel between the hydrophone and the rest of the channel using a switch component. The switch component can have multiple operating modes set by a switch control unit to control the signal flow through the hydrophone channel. In the normal operating mode, the switch component can disconnect the test signal generator from the hydrophone channel. In the disconnected state, the switch component allows the electrical signal converted from the acoustic signal by the sensor to pass through the hydrophone channel to the signal encoder for additional processing.

[0034] In addition, the switch component can connect the test signal generator in series with the hydrophone channel to transmit the test signal. When connecting the test signal generator with the hydrophone channel, the switch component can route the test signal generated by the test signal generator through the hydrophone channel in a first direction or a second direction. In one test operation mode, the switch component can route the test signal from the test signal generator first through one terminal (e.g., the positive terminal) of the sensor via the hydrophone channel to the signal encoder. In another test operation mode, the switch component can route the test signal from the test signal generator first through the opposite terminal (e.g., the negative terminal) of the sensor via the hydrophone channel to the signal encoder.

[0035] By connecting in series in the test operating mode, the test signal generator can be used as a voltage divider directly between the hydrophone channel and the hydrophone. In this way, the impedance of the hydrophone can be measured using the lower frequency of the test signal, allowing for a more refined and sensitive measurement of the hydrophone. In addition, using these two test operating modes, a bipolar measurement of the impedance of the hydrophone can be performed on the hydrophone channel. By performing a bipolar measurement, it can be determined whether the hydrophone is balanced or unbalanced. In this way, it can be determined at an earlier point in the life cycle of the node than with a parallel configuration whether the performance of the hydrophone is degrading.

[0036] in, Figure 1 An isometric view of an environment 100 for seismic operations in deep water is depicted. The environment 100 may include a body of water 105, such as an ocean, sea, lake, bay, harbor, or river, etc. The environment 100 may include an underwater surface 110 below the water 105. The surface 110 may correspond to the bottom of the body of water 105, such as the seafloor, seabed, or lake bottom, etc. Below the surface 110, the environment 100 may include lithologic formations or fluid layers associated with the presence of hydrocarbons, minerals, or other elements.

[0037] Environment 100 may include at least one first container 115. First container 115 may be a watercraft, such as a ship, a transport, a tanker, a merchant ship, a tugboat, a submarine, etc. First container 115 may be on the surface of water 105 (e.g., as depicted) or within water 105. First container 115 may include at least one crane 120 having at least one cable 125 and at least one transfer mechanism 130 attached at the end of cable 125. Transfer mechanism 130 may be a container, a baffle, a carrier, a slide structure, a basket, or any component capable of holding and transporting an object. Environment 100 may include a set of devices 140 (also referred to herein as seismic sensor devices, seismic data acquisition units, or nodes) for acquiring seismic data arranged along surface 110 below water 105. Each device 140 may initially be transported by first container 115. Once first container 115 is positioned on the surface of water 105 along water column 135, each device 140 may be loaded onto transfer mechanism 130. Transfer mechanism 130 holding device 140 is lowered via crane 120 and cable 125 to a location on surface 110 beneath water 105. Upon reaching surface 110, transfer mechanism 130 may unload or place 125 device 140 at a location on surface 110.

[0038] The set of devices 140 can be placed at selected locations on the surface 110, such as multiple rows Rn in the X direction (R1 and R2 are shown) or columns Cn in the Y direction (Cl-Cn are shown), where n is equal to an integer. The rows Rn and columns Cn can define a grid or array, where each row Rn (e.g., R1-R2) includes receiver lines over the width (X direction) of the sensor array, or each column Cn includes receiver lines over the length (Y direction) of the sensor array. The distance between adjacent devices 140 in a row is shown as distance LR, and the distance between adjacent devices 140 in a column is shown as distance LC. Although a generally square pattern is shown (e.g., as depicted), other patterns can be formed on the surface 110. Other patterns include non-linear receiver lines or non-square patterns. The pattern can be predetermined or generated by other factors such as the topography of the surface 110. The distances LR and LC can be substantially equal and can include dimensions between about 60 meters and about 400 meters or more. The distance between adjacent devices 140 may be predetermined or result from the topography of surface 110 .

[0039] The environment 100 may include at least one second container 145. The second container 145 may be a watercraft, such as a ship, a transport, a tanker, a merchant ship, a tugboat, a submarine, etc. The second container 145 may be on the surface of the water 105 (e.g., as depicted) or within the water 105. The second container 145 may include at least one acoustic source device 150 (e.g., an air gun array) to perform seismic surveys. The first container 115 may also include an acoustic source device 150 to perform seismic surveys. As the device 140 is placed along the surface 110 below the water 105, the acoustic source device 150 on the second container 145 may emit an acoustic signal to the array of the device 140. The acoustic signal may propagate to the surface 110, and a portion of the signal may be refracted or reflected and may reach the array of the device 140. The second container 145 may transmit multiple times per single receiver line (e.g., row R1), for example, at least four times. By acquiring the acoustic signals, the data generated by the device 140 may be used to determine whether the underlying surface 110 contains lithological formations or fluid layers associated with the presence of hydrocarbons, minerals, or other elements.

[0040] in, Figure 2 An isometric view of an apparatus 140 (also referred to herein as a seismic sensor device, seismic data acquisition unit, or node) for acquiring seismic data is depicted. The apparatus 140 may have at least one housing 200. The housing 200 may contain, hold, or otherwise include one or more components of the apparatus 140. The housing 200 may define one or more cavities therein to hold or secure the components of the apparatus 140. When the apparatus 140 is placed on a surface 110, the housing 200 may separate at least some of the contained components from the water 105. The housing 200 may prevent the water 105 from entering so as not to contact at least some of the components contained within the housing 200. The housing 200 may have any shape, such as a cylinder (e.g., as depicted), a prism with a polygonal base, a pyramid, or a sphere, etc.

[0041] The housing 200 of the device 140 may have at least one longitudinal side 205 (also referred to herein as a side). The longitudinal side 205 may correspond to or include a portion of the housing 200 along a longitudinal axis or a vertical axis of the device 140 (e.g., as depicted). The housing 200 may have at least one lateral side 210 (also referred to herein as a top side). The lateral side 210 may correspond to or include a portion of the housing 200 along a lateral axis or a horizontal axis of the device 140 (e.g., as depicted). The housing 200 may have at least one second lateral surface 215 (also referred to herein as a bottom side). The second lateral surface 215 may correspond to or include a portion of the device 140 along a lateral axis or a horizontal axis of the device 140 opposite the lateral side 210. The first lateral surface 210 or the second lateral surface 215 may be perpendicular or substantially perpendicular (e.g., 60° to 120°) to the longitudinal surface 205. The height of the housing 200 defined by the longitudinal side 205 may range from 5" to 20". The width of housing 200 (or the diameter of the cylindrical shape) defined by at least one of lateral surfaces 210 and 215 may range between 10" and 30".

[0042] The device 140 may include at least one first fixing mechanism 220 (also referred to herein as an outer cleat). The device 140 may include at least one second fixing mechanism 225 (also referred to herein as an inner cleat). When the device 140 is placed underwater, the first fixing mechanism 220 and the second fixing mechanism 225 may fix or hold the housing 200 of the device 140 along the surface 110. The first fixing mechanism 220 and the second fixing mechanism 225 may be placed or arranged on the first lateral surface 210 or the second lateral surface 215 (e.g., as depicted). The first fixing mechanism 220 may be located adjacent to or close to (e.g., within 2" to 5") the second fixing mechanism 225 along the lateral surface 210 or 215. The first fixing mechanism 220 may form a first perimeter, and the second fixing mechanism 225 may form a second perimeter. The first perimeter of the first fixing mechanism 220 may be along the outer edge of the lateral surface 210 or 215. The second perimeter of the second fixing mechanism 225 may be separated from the edge of the lateral surface 210 or 215.

[0043] The device 140 may include at least one connector 230. The connector 230 may be placed or disposed along the longitudinal side 205 (e.g., as depicted) or one of the lateral sides 210 or 215. The connector 230 may allow at least one external device to be electrically coupled to components within the device 140 for wired communication. The device 140 may include at least one coupling mechanism 235. The coupling mechanism 235 may be placed or disposed along the longitudinal side 205 (e.g., as depicted) or one of the lateral sides 210 or 215. The coupling mechanism 235 may facilitate coupling the device 140 or facilitate deployment or storage of the device 140. For example, the coupling mechanism 235 may include a loop through which a cable may be inserted to facilitate deployment of the device 140 in the environment 100. The device 140 may include at least one transceiver 240. The transceiver 240 may be placed or disposed along the longitudinal side 205 (e.g., as depicted) or one of the lateral sides 210 or 215. The transceiver 240 can send and receive radio frequency (RF) signals to allow wireless communication with at least one external device. Communication via the transceiver 240 can facilitate the transmission of position detection, positioning, or information related to seismic operations (such as seismic data, status information, or quality assessment, etc.). The device 140 can include an RFID tag. The RFID tag can be used to identify the device 140. The RFID tag can be used to identify the device 140 outside the water. The RFID can contain static identification information. The identification information can be used to identify which device 140 is deployed. The identification information can be used to identify when a specific device 140 is deployed.

[0044] The device 140 may include or define at least one hydrophone opening 245 (also referred to herein as a slot or opening). The hydrophone opening 245 may be placed, arranged, or positioned along the longitudinal side 205 (e.g., as depicted) or one of the lateral sides 210 or 215. The hydrophone opening 245 may allow at least one of the components contained in the housing 200 to contact the water 105 to receive acoustic signals propagated through the water 105. The hydrophone opening 245 may allow at least one of the components of the housing 200 to be mechanically coupled to the water 105 (e.g., via a metal membrane or ceramic cover) to receive acoustic signals propagated through the water 105. The hydrophone opening 245, together with the components within the housing 200, may facilitate the transmission of position detection, positioning, or information related to seismic operations (such as seismic data, status information, or quality assessment, etc.). The device 140 may include a zinc anode 250. The zinc anode 250 may protect the device 140 from corrosion caused by electrolysis. The zinc anode 250 may be referred to as a sacrificial anode. The device 140 may include a pressure relief port 255 .

[0045] in, Figure 3A circuit diagram of the sensor 300 is depicted (e.g., depicted generally along the left side). The sensor 300 can be housed, disposed, or arranged within the housing 200 of the device 140. At least a portion of the sensor 300 can be in contact with or mechanically coupled to the water 105 via the hydrophone opening 245 of the device 140 (e.g., via a membrane or cover). The sensor 300 can be a piezoelectric sensor and can include at least one piezoelectric component 305. The piezoelectric component 305 can be composed of a material that exhibits piezoelectricity that converts mechanical stress into an electrical charge. Materials for the piezoelectric component 305 can include, for example: naturally occurring crystals (e.g., quartz, topaz, tourmaline, pyrophosphate, and Rochelle salt), synthetic crystals (e.g., lanthanum gallium silicate (La3Ga5SiO 14 ), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), and gallium orthophosphate (GaPO4)), ceramic materials (e.g., barium titanate (BaTiO3), lead zirconate titanate (PZT), lead titanate (PbTiO3), potassium niobate (KNbO3), and sodium tungstate (Na2WO3)), lead-free piezoelectric ceramics (e.g., potassium sodium niobate (NaKNbO3), bismuth ferrite (BiFeO3), barium titanate (BaTiO3), bismuth titanate (Bi4Ti3O 12 ) and sodium niobate (NaBi(TiO3)2)), polymers (e.g., polyvinylidene fluoride (PVDF)) and semiconductors (e.g., zinc oxide (ZnO) with a wurtzite structure), etc.

[0046] The sensor 300 may have a first terminal 310 and a second terminal 315 (also referred to herein as polarity terminals). Each terminal 310 and 315 of the sensor 300 may correspond to a corresponding terminal of the piezoelectric component 305. The terminals 310 and 315 may have polarities opposite to each other. For example, when the first terminal 310 has a positive polarity, the second terminal 315 may have a negative polarity. The sensor 300 may generate a transmitting alternating current (AC), and the polarities of the terminals 310 and 315 may also alternate with the alternating current. The positive terminal may correspond to the end from which the conventional current of the sensor 300 may flow out. The negative terminal may correspond to the opposite end into which the conventional current of the sensor 300 may flow.

[0047] The sensor 300 may convert at least one incoming acoustic signal 320 into at least one electrical signal 325 via the piezoelectric component 305. When received at the piezoelectric component 305, the acoustic signal 320 may traverse or pass through a liquid or aqueous medium (e.g., a body of water 105 in the environment 100). The acoustic signal 320 may be emitted by the acoustic source device 150 and may be reflected or refracted by a lithological feature below the surface 110 in the environment 100. Upon refraction or reflection, the acoustic signal 320 may reach the device 140. At least a portion of the piezoelectric component 305 may be positioned or arranged within a hydrophone opening 245 of the device 140. The portion of the piezoelectric component 305 is in contact with or mechanically coupled to the water 105 to receive the acoustic signal 320 (e.g., through the hydrophone opening 245). The piezoelectric component 305 (or the mechanical coupling between the piezoelectric component 305 and the water 105) may have an acoustic impedance that matches the acoustic impedance of the liquid medium (e.g., water 105). Through impedance matching, contact with acoustic signal 320 propagating through the liquid medium can generate or induce mechanical stress on piezoelectric component 305. The mechanical stress can induce piezoelectric component 305 to generate electrical signal 325 for transmission to electronic components coupled to sensor 300.

[0048] The operating characteristics of the sensor 300 may be characterized or approximated using a model circuit 350 (e.g., depicted generally along the right side) (also referred to herein as an equivalent circuit). The depicted example of the model circuit 350 may be a Norton equivalent circuit, but other equivalent circuits (e.g., a Thevenin equivalent circuit) may also be used to characterize or approximate the operating characteristics of the sensor 300. The model circuit 350 may include at least one alternating current (AC) voltage source 355 and one or more impedance components (such as at least one capacitor 360 and at least one resistor 365). The model circuit 350 may also include at least one inductor. The AC voltage source 355, the capacitor 360, and the resistor 365 may be coupled in parallel or in series with each other, or in any combination. For example, as depicted, the AC voltage source 355 may be coupled in series with the capacitor 360. The AC voltage source 355 and the capacitor 360 together may be coupled in parallel with the resistor 365.

[0049] Within the model circuit 350, the AC voltage source 355 may correspond to or represent the generated voltage when mechanical stress is generated on the piezoelectric component 305. The AC voltage source 355 may have a sensitivity of 84 μV / Pa (8.4 V / bar). The AC voltage source 355 may have a sensitivity of 89 μV / Pa (8.9 V / bar). The device 140 may digitize input signals within a range of + / -2.5V. Therefore, the maximum sound pressure level input may range between 28.1 kPa (281 mbar) and 29.8 kPa (298 mbar). If pressures greater than these are applied, the hydrophone may generate a voltage greater than the maximum value that the channel input may accurately digitize. The capacitor 360 may correspond to or represent the inherent capacitance of the piezoelectric component 305, such as static capacitance and capacitance caused by mechanical stress (e.g., changes in water pressure) from the acoustic signal 320. The capacitance of the capacitor 360 for a piezoelectric component 305 that is operating normally may range between 10 nF (+ / -15%). The resistor 365 may correspond to or represent the leakage resistance of the piezoelectric component 305 that the electrical signal 325 generated by the generation of mechanical stress faces. The resistance of the resistor 365 for a properly functioning piezoelectric component 305 may be approximately 270 MΩ (+ / - 15%). The resistance of the resistor 365 for a properly functioning piezoelectric component 305 may be greater than 270 MΩ.

[0050] in, Figure 4 A circuit diagram of an electronic circuit or system 400 for measuring hydrophone impedance is depicted. System 400 may include one or more electronic components coupled to each other. Components of system 400 may be housed, contained, or otherwise included within device 140 (such as within housing 200). Components of system 400 may be arranged on or implemented using one or more printed circuit boards (PCBs), stamped circuit boards (SCBs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), multi-chip modules, breadboards, wraparound boards, and shipboards, etc., or any combination thereof. System 400 may include sensor 300 and other components. Sensor 300 may be coupled to one or more components in system 400. Sensor 300 may convert an incoming acoustic signal 320 into an electrical signal 325. When coupled to other components of system 400, sensor 300 may transmit electrical signals 325 generated in response to the generation of mechanical stress from acoustic signal 320 to the other components.

[0051] The system 400 may include at least one signal encoder 402 (sometimes referred to herein as a delta-sigma modulator). The signal encoder 402 may be coupled to one or more components of the system 400. The signal encoder 402 may be coupled to the sensor 300 in parallel, for example, via other components of the system 400. The signal encoder 402 may have at least one input channel 418. The input channel 418 may correspond to or may define the coupling of the signal encoder 402 to the rest of the system 400 (including the sensor 300). The input channel 418 may define a first terminal and a second terminal having opposite polarities to each other. Each terminal of the input channel 418 may have one or more connections to other components of the system 400. The first terminal of the input channel 418 may correspond to and be coupled to the first terminal 310 of the sensor 300 having the same polarity. Conversely, the second terminal of the input channel 418 may correspond to and be coupled to the second terminal 315 of the sensor 300 having the same polarity. When coupled in parallel with sensor 300 via input channel 418 and other components of system 400, signal encoder 402 may receive electrical signal 325 from sensor 300. Electrical signal 325 may pass through other components of system 400 and be relayed to signal encoder 402.

[0052] The signal encoder 402 may include at least one analog-to-digital converter (ADC) unit 420. The ADC unit 420 may include a circuit that converts an electrical signal in the analog domain into an electrical signal in the digital domain. The signal in the digital domain in the system 400 may represent a sequence of discrete values. For example, the signal in the digital domain may represent a binary value and may include a series of pulses generated using pulse amplitude modulation, where a high voltage represents a "1" in binary and a low voltage represents a "0" in binary. Upon receiving, the ADC unit 420 may convert the electrical signal 325 from the analog domain to the digital domain. The electrical signal 325 may initially be in the analog domain. In order to convert, the ADC unit 420 may sample the electrical signal 325 from the sensor 300. For a sampling interval of 4ms to 0.5ms, the sampling rate of the ADC unit 420 may range between 250Hz and 2kHz. For example, for a sampling interval of 2ms, the sampling rate of the ADC unit 420 may be 500Hz. When sampling, the ADC unit 420 can perform quantization on the sampled electrical signal 325 to generate a signal 468 in the digital domain (sometimes also referred to herein as a synthesized signal). The signal 468 generated by the ADC unit 420 can be a digital domain representation of the electrical signal 325 of the sensor 300 from the analog domain. The signal encoder 402 can send, transmit, or output the signal 468 via at least one output channel 430 for additional processing.

[0053] Between the input channel 418 and the ADC unit 420, the signal encoder 402 may include one or more components for modulating the received electrical signal 325, such as a set of multiplexers 422, at least one impedance component 424, a set of amplifiers 426, and at least one gain controller 428. The set of multiplexers 422 (sometimes referred to herein as multiplexers (mux)) may be coupled to one or more other components of the system 400 via the input channel 418. Each multiplexer 422 may couple the signal encoder 402 to other components of the system 400. Each multiplexer 422 may be configured (e.g., using a control signal) to allow the electrical signal 325 from the sensor 300 to be transmitted to the ADC unit 420 or to transmit the electrical signal 325 from the sensor 300 to the ADC unit 420. Each multiplexer 422 may be configured (e.g., using a control signal) to limit or block the electrical signal 325 from the sensor 300 from being transmitted to the ADC unit 420, and to allow a signal from another component to pass through. The impedance component 424 may include a resistor (e.g., having a resistance value of 800Ω as depicted), a capacitor, or an inductor, etc., and may be connected between the group of multiplexers 422 to provide a reference impedance for the electrical signal 325. The group of amplifiers 426 may include an operational amplifier (e.g., as depicted), a transistor amplifier, or a differential amplifier (e.g., an instrument amplifier), etc. Each amplifier 426 may amplify the electrical signal 325 from the sensor 300 that passes through other components before being input to the ADC unit 420. A gain controller 428 is coupled to each of the amplifiers 425 and may adjust, adjust, or set the amount or factor of amplification applied to the electrical signal 325 by the amplifier 426. The amplification factor may range from 1 to 64. For example, the amplification factor may be 1, 2, 4, 8, 16, 32, or 64.

[0054] System 400 may include at least one input filter network 404 (sometimes generally referred to herein as a filter circuit or filter). Input filter network 404 may be coupled to other components of system 400. Input filter network 404 may be coupled in parallel between sensor 300 and input channel 418 of signal encoder 402 (e.g., as depicted). Toward sensor 300, input filter network 404 may have a set of terminals connected to sensor 300 to couple input filter network 404 to input filter network 404. The set of terminals may have opposite polarities to one another. A first terminal of input filter network 404 may correspond to and be coupled to first terminal 310 of sensor 300 having the same polarity. A second terminal of input filter network 404 may correspond to and be coupled to second terminal 315 of sensor 300 having the same polarity. Conversely, toward signal encoder 402, input filter network 404 may have a set of terminals connected to input channel 418 of signal encoder 402. The set of terminals may have opposite polarities to one another. A first terminal of the input filter network 404 may correspond to and be coupled to a first terminal of the input channel 418 having the same polarity. A second terminal of the input filter network 404 may correspond to and be coupled to a second terminal of the input channel 418 having the same polarity. The input filter network 404, along with the sensor 300 and at least the input channel 418 of the signal encoder 402, may be part of a hydrophone channel in the system 400.

[0055] When connected in parallel with the sensor 300 and the signal encoder 402, the input filter network 404 can transmit or transfer the electrical signal 325 received from the sensor 300 to the signal encoder 402. When the electrical signal 325 is transmitted from the sensor 300 through the input filter network 404 to the signal encoder 402, the input filter network 404 can apply a filtering operation to the electrical signal 325. The filtering operation can be in the analog domain (e.g., as depicted) or in the digital domain. When applying the filtering operation, the input filter network 404 can amplify, attenuate or maintain the electrical signal 325 at a specific frequency component. For example, the filtering operation can include a low-pass filter, a high-pass filter, a band-pass filter, a passband filter, or an all-pass filter, or any combination thereof. The filtering operation can be based on any number of filter families, such as a Bessel filter, a Butterworth filter, a Chebyshev filter, an elliptic filter, a Gaussian filter, or a raised cosine filter, or the like.

[0056] In order to obtain a filtering operation with a desired operating characteristic, the input filter network 404 can have a set of impedance components connected in series, in parallel, or in a combination of series and parallel to each other. For example, as depicted, the set of impedance components in the input filter network 404 can include a resistor 432 having a resistance of 10 MΩ (+ / -15%) connected in parallel with the sensor 300. The input filter network 404 can also include a set of capacitors 434 connected in series with the sensor 300 and the resistor 432, each capacitor 434 having a capacitance of 33 nF (+ / -15%). The input filter network 404 can include a set of resistors 436 connected in parallel with the sensor 300, each resistor 436 having a resistance of 6.81 MΩ (+ / -15%). The input filter network 404 can include a set of resistors 438 connected in series with the sensor 300, each resistor 438 having a resistance of 10 kΩ (+ / -15%). Input filter network 404 may include a set of capacitors 440, each having a capacitance of 10 pF (+ / - 15%), connected in parallel with sensor 300. With impedance components connected in this manner, input filter network 404 may function as a bandpass filter having a lower cutoff frequency of 3.15 Hz and a higher cutoff frequency of 1.6 MHz.

[0057] The system 400 may include at least one test signal generator 406. The coupling of the input signal generator 406 to the sensor 300 and the signal encoder 402 may be controlled via one or more other components of the system 400. The test signal generator 406 may be coupled in series with the sensor 300 and the signal encoder 402. As depicted, for example, the test signal generator 406 may be coupled in series between the sensor 300 and the input filter network 404. Coupled in this manner, an electrical connection may be formed from the sensor 300 through the test signal generator 406 and then to the input filter network 404 and then to the signal encoder 402. The test signal generator 406 may also be disconnected in series with the sensor 300 and the signal encoder 402 to allow the electrical signal 325 to be transmitted from the sensor 300 to the signal encoder 402 without passing through the test signal generator 406.

[0058] The test signal generator 406 may have a plurality of groups of terminals connected to the sensor 300 and to the signal encoder 402 via the input filter network 404. Toward the signal encoder 402, the test signal generator 406 may have a group of terminals connected to the input channel 418 of the signal encoder 402 via the input filter network 404. The group of terminals may have opposite polarities to each other. The first terminal of the test signal generator 406 may correspond to and be connected to the first terminal of the input channel 418 with opposite polarity. The second terminal of the test signal generator 406 may correspond to and be connected to the second terminal of the input channel 418 with opposite polarity. Toward the sensor 300, the test signal generator 406 may have a group of terminals 452 and 454 connected to the sensor 300 to connect the test signal generator 406 to the test signal generator 406. The group of terminals 452 and 454 may have opposite polarities to each other. The coupling of the terminals 452 and 454 of the test signal generator 406 to the terminals 310 and 315 of the sensor 300 may be modified, set, or controlled.

[0059] The test signal generator 406 can generate one or more test signals to be sent and passed through one or more of the various components of the system 400. The test signal sent through the system 400 can be in the analog domain. The test signal can have one or more characteristics defined or set by another component in the system 400. The characteristics of the test signal can include, for example, amplitude, period, frequency, duration, and signal waveform. When coupled to the sensor 300 and the signal encoder 402, the test signal generator 406 can send the test signal through the sensor 300, the input filter network 404, and the signal encoder 402. When disconnected from the sensor 300 and the signal encoder 402, the test signal generator 406 can limit or omit the transmission of the test signal through the sensor 300, the input filter network 404, and the signal encoder 402.

[0060] In order to generate and send the test signal, the test signal generator 406 may include at least one digital-to-analog converter (DAC) unit 442. The DAC unit 442 may include a circuit for converting an electrical signal from a digital domain to an analog domain. The signal in the digital domain may be received from one or more other components in the system 400 via at least one input channel 446 of the test signal generator 406. The signal in the digital domain may include timing data representing the value (e.g., binary number, floating point value, or integer) of the signal to be formed in the analog domain. In order to convert, the DAC unit 442 may include (e.g., by applying a zero-order hold) a sequence of pulses generated using the received signal in the digital domain. When generating the pulse, the DAC unit 442 may be upsampled at a sampling rate of 0.4883 Hz to 250 Hz. The output level may be controlled by both analog gain (in 6 dB steps) and digital gain (in 0.5 dB steps). The DAC unit 442 may apply or perform an interpolation operation (e.g., using a reconstruction filter) to output an electrical signal in the analog domain as a test signal. While applying the interpolation operation, DAC unit 442 sends the test signal to other components of system 400 , such as sensor 300 , input filter network 404 , and signal encoder 402 .

[0061] Between the DAC unit 442 and the other components of the system 400, the test signal generator 406 may include at least one set of output regulators 444 to control the output of electrical signals from the DAC unit 442 to the rest of the system 400. Each output regulator 444 may include a component capable of amplification and switching, such as a field effect transistor (FET) (e.g., a metal oxide semiconductor field effect transistor (MOSFET) or a junction field effect transistor (JFET)) or a bipolar junction transistor (BJT), etc. The output regulator 444 may be connected in series between the output of the test signal generator 406 and the DAC unit 442. When connected to the DAC unit 442, the output regulator 444 may amplify the test signal to be sent to the other components of the system 400. In addition, the output regulator 444 may control whether the test signal is transmitted to the rest of the system 400 by limiting or allowing the test signal to be transmitted from the DAC unit 442 through the output regulator 444.

[0062] The system 400 may include an impedance library 408 (also referred to herein as a set of impedance components). The impedance library 408 may include a set of impedance components 448 connected in series with the sensor 300 and with the test signal generator 406. The set of impedance components 448 may include resistors (e.g., as depicted), capacitors, and inductors, among others. For example, as depicted, the set of impedance components 448 may include resistors and may have a resistance of 422Ω (+ / -10%). When connected in series between the sensor 300 and the test signal generator 406, the set of impedance components 448 may control or adjust the voltage of the test signal generated and sent by the test signal generator 406. The impedance library 408 may also include a set of impedance components 450 connected in series with the signal encoder 402 and the test signal generator 406. The set of impedance components 450 may include resistors (e.g., as depicted), capacitors, and inductors, among others. For example, as depicted, the set of impedance components 450 may include a resistor and may have a resistance of 422Ω (+ / -10%). When connected in series between the test signal generator 406 and the signal encoder 402, the set of impedance components 450 may control or adjust the voltage of the signal between the test signal generator 406 and the signal encoder 402.

[0063] The system 400 may include at least one switch component 410 (sometimes referred to herein as a switch network). The switch component 410 may be coupled to the sensor 300, the signal encoder 402 (via the input filter network 404), and the test signal generator 406 (via the impedance library 408). The switch component 410 may set, modify, or otherwise control the coupling of the test signal generator 406 to the sensor 300 and the signal encoder 402. The setting of the coupling by the switch component 410 may be commanded based on one or more signals from other components in the system 400. When controlling the coupling, the switch component 410 may couple the test signal generator 406 in series between the sensor 300 and the signal encoder 402 (e.g., via the input filter network 404). The switch component 410 may control the coupling of the terminals 452 and 454 of the test signal generator 406 to the terminals 310 and 315 of the sensor 300. When connected in series, an electrical signal flowing through the system 400 may pass from the test signal generator 406, then reach the sensor 300, then reach the input filter network 404, and then reach the signal encoder 402. The direction in which the electrical signal flows through the system 400 may depend on the connection of the terminals 452 and 454 of the test signal generator 406 to the terminals 310 and 315 of the sensor 300. Conversely, the switch component 410 may disconnect the test signal generator 406 from the sensor 300, the signal encoder 402, and the input filter network 404. When disconnected, an electrical signal (e.g., the electrical signal 325) flowing through the system 400 may pass from the sensor 300, then reach the input filter network 404, and then reach the signal encoder 402 without passing through the test signal generator 406.

[0064] In order to set up connections between components of the system 400, the switch component 410 may include a set of switches, such as the four switches 456-462 depicted. Each switch 456-462 may include at least one component capable of switching or regulating current, such as a field effect transistor (FET) (e.g., a metal oxide semiconductor field effect transistor (MOSFET) or a junction field effect transistor (JFET)), a bipolar junction transistor (BJT), or a mechanically operable trigger, etc. For example, as depicted, each switch 456-462 may be a pair of field effect transistors, each having a source terminal, a drain terminal, and a gate terminal. By configuring the set of switches 456-462, the switch component 410 can set or control the connection and disconnection of the test signal generator 406 with the sensor 300, the input filter network 404, and the signal encoder 402. In each switch 456 - 462 , the gate terminal of each field effect transistor may be coupled to another component of the system 400 to receive a command signal to couple or disconnect the test signal generator 406 from the sensor 300 and the signal encoder 402 via the input filter network 404 .

[0065] The set of switches 456-462 may be coupled to one of the first terminal 310 and the second terminal 315 of the sensor 300. Switches 456 and 458 (sometimes collectively referred to herein as positive terminal switches) may be coupled to the second terminal 315 of the sensor 300, the signal encoder 402 via the input filter network 404, and the test signal generator 406. Continuing with the depicted example, in switch 456, the source terminals of the two field effect transistors in a pair may be coupled to the second terminal 315 of the sensor 300. In switch 456, the drain terminal of one of the field effect transistors (e.g., the bottom field effect transistor in the figure) may be coupled to the signal encoder 402 via the input filter network 404 and switch 458. The drain terminal of the other field effect transistor in the pair of switch 456 (e.g., the top field effect transistor in the figure) may be coupled to the test signal generator 406 via the impedance library 408. In addition, in switch 458, the drain terminals of the two field effect transistors in a pair can be coupled to one of the terminals of the input channel 418 of the signal encoder 402 via the input filter network 404. In switch 456, the source terminal of one of the field effect transistors (e.g., the bottom field effect transistor in the figure) can be coupled to the second terminal 315 of the sensor 300 via switch 456. The source terminal of the other field effect transistor in the pair of switch 458 (e.g., the top field effect transistor in the figure) can be coupled to the test signal generator 406 via the impedance library 408.

[0066] Conversely, switches 460 and 462 (sometimes collectively referred to herein as negative terminal switches) can be coupled to the first terminal 310 of the sensor 300, the signal encoder 402 via the input filter network 404, and the test signal generator 406. In the example as depicted, in switch 460, the source terminals of the two field effect transistors in a pair can be coupled to the first terminal 310 of the sensor 300. In switch 460, the drain terminal of one of the field effect transistors (e.g., the top field effect transistor in the figure) can be coupled to the signal encoder 402 via the input filter network 404 and switch 462. The drain terminal of the other field effect transistor in the pair of switch 460 (e.g., the bottom field effect transistor in the figure) can be coupled to the test signal generator 406 via the impedance library 408. Additionally, in switch 462, the drain terminals of the two field effect transistors in a pair can be coupled to one of the terminals of the input channel 418 of the signal encoder 402 via the input filter network 404. In switch 462, a source terminal of one of the field effect transistors (e.g., the top field effect transistor in the figure) can be coupled to first terminal 310 of sensor 300 via switch 460. A source terminal of the other field effect transistor in the pair of switches 462 (e.g., the bottom field effect transistor in the figure) can be coupled to test signal generator 406 via impedance library 408.

[0067] The system 400 may include at least one first switch control 412 (sometimes referred to herein as a positive polarity terminal switch control). The first switch control 412 may control the connection of the test signal generator 406 to the sensor 300 and the signal encoder 402 via the switch control 410. To control the connection of the test signal generator 406, the first switch control 412 may be coupled to each of the switches 456 and 458, which may be coupled to the second terminal 315 of the sensor 300. For example, as depicted, the first switch control 412 may be coupled to each of the gate terminals of all field effect transistors in the switches 456 and 458 to control the flow through the source terminal and the drain terminal. When coupled to the switches 456 and 458, the first switch control 412 may apply, transmit, or otherwise send an activation signal to each of the switches 456 and 458 to control the connection or disconnection of the test signal generator 406 to the sensor 300 and the signal encoder 402 via the input filter network 404. The activation signal may be provided or directed by another component in the system 400 that is coupled to the first switch control 412 .

[0068] The system 400 may include at least one second switch control 414 (sometimes referred to herein as a negative polarity terminal switch control). The second switch control 414 may control the connection of the test signal generator 406 to the sensor 300 and the signal encoder 402 via the switch control 410. To control the connection of the test signal generator 406, the second switch control 414 may be coupled to each of the switches 460 and 462. For example, as depicted, the second switch control 414 may be coupled to each of the gate terminals of all field effect transistors in the switches 460 and 462 to control the flow through the source terminal and the drain terminal. When coupled to the switches 460 and 462, the second switch control 414 may apply, transmit, or otherwise send an activation signal to each of the switches 460 and 462 to control the connection or disconnection of the test signal generator 406 to the sensor 300 and the signal encoder 402 via the input filter network 404. The activation signal may be provided or directed by another component in the system 400 coupled to the second switch control 414.

[0069] The system 400 may include at least one instrument component 416 (also referred to herein as an impedance measurer). The instrument component 416 may measure, calculate, or determine one or more operating characteristics of at least the sensor 300 and other components in the system 400. For example, the instrument component 416 may determine operating characteristics of a hydrophone channel including the sensor 300, the input filter network 404, and the input channel 418 to the signal encoder 402. The operating characteristics may include impedances such as resistance (e.g., as modeled by resistor 365), capacitance (e.g., as modeled by capacitor 360), and inductance of the sensor 300. The impedance may be measured by the instrument component 416 relative to a test signal applied to the sensor 300 and other components of the system 400. The operating characteristics determined by the instrument component 416 may include a frequency response of the sensor 300 (or the hydrophone channel) to the test signal applied through the sensor 300 (e.g., in the form of a transfer function).

[0070] Instrument component 416 may include one or more components that may be coupled to one or more other components in system 400 (e.g., Fig.144). The instrument component 416 can be coupled to the output channel 430 of the signal encoder 402 to receive the signal 468. The instrument component 416 can be coupled to the input channel 446 of the test signal generator 406. The instrument component 416 can be coupled to the first switch control 412 to control the switch component 410 to connect or disconnect the test signal generator 406 with the sensor 300 and the signal encoder 402 via the input filter network 404. The instrument component 416 can be coupled to the second switch control 414 to control the switch component 410 to connect or disconnect the test signal generator 406 with the sensor 300 and the signal encoder 402 via the input filter network 404. The instrument component 416 can be separate from the switch controls 412 and 414 and the test signal generator 406 (e.g., as depicted). The instrument component 416 can include the switch controls 412 and 414 and the test signal generator 406. The instrumentation component 416 may receive the signal and feed the signal to the connected components (eg, the signal encoder 402 , the test signal generator 406 , and the switch controls 412 and 414 ) in the digital domain.

[0071] The instrument component 416 can set or control the operating state of the system 400. The operating state can define or specify the flow of electrical signals through the system 400 from the sensor 300 to the signal encoder 402. The operating state can include a normal operating state and one or more test operating states. The normal or default operating state can specify that the test signal generator 406 is disconnected from the sensor 300, the input filter network 404, and the signal encoder 402. Conversely, the test operating state can specify that the test signal generator 406 is connected in series between the sensor 300 and the signal encoder 402 via the input filter network 404 and provides a test signal for measuring the operating characteristics of the sensor 300. During the test operating state, the instrument component 416 can measure the operating characteristics of the sensor 300 (or the hydrophone channel).

[0072] To set the operating state of the system 400, the instrument component 416 may generate one or more activation signals (sometimes referred to herein as command signals) and provide them to the components of the system 400. The setting of the operating state may be provided by a user input (e.g., an administrator or operator of the device 140) via an input / output (I / O) interface coupled to the device 140 or the instrument component 416 of the system 400. The instrument component 416 may determine or identify the operating state set for the system 400. Based on the identified operating state, the instrument component 416 may identify activation signals applied to the components of the system 400. Upon identification, the instrument component 416 may generate one or more activation signals and send them to the components of the system 400, such as the switch controls 412 and 414 and the test signal generator 406.

[0073] In a normal operating state, the instrument component 416 can provide or apply one or more activation signals to the first switch control 412 and the second switch control 414. The application of the activation signal by the instrument component 416 can be in response to identifying the operating state as normal. The activation signal applied to the first switch control 412 can specify switches 456 and 458 to allow the electrical signal 325 to flow from the sensor 300 through the input filter network 404 to the signal encoder 402. The activation signal applied to the first switch control 412 can specify switches 456 and 458 to disconnect the test signal generator 406 from the sensor 300 and the signal encoder 402 via the input filter network 404. Similarly, the activation signal applied to the second switch control 414 can specify switches 460 and 462 to allow the electrical signal 325 to flow from the sensor 300 through the input filter network 404 to the signal encoder 402. The activation signal applied to the second switch control 414 can specify that the switches 460 and 462 disconnect the test signal generator 406 from the sensor 300 and the signal encoder 402 via the input filter network 404. In this way, during normal operating conditions, the instrument component 416 can allow the system 400 (including the sensor 300, the input filter network 404, and the signal encoder 402) to function. The instrument component 416 can prohibit any signal from the test signal generator 406 from being transmitted through the sensor 300 and the input filter network 404 or applied to the signal encoder 402. The instrument component 416 can also prevent or stop performing a determination of the operating characteristics of the sensor 300.

[0074] in, Figure 5 A circuit diagram of a system 400 for measuring hydrophone impedance in a first test operating state 500 is depicted. The first test operating state 500 may facilitate measuring an operating characteristic of a sensor 300 in one path or direction. The first test operating state 500 may specify that a first terminal 452 of a test signal generator 406 is coupled to a first terminal 310 of a sensor 300. The first test operating state 500 may also specify that a second terminal 454 of the test signal generator 406 is coupled to one of the terminals of an input channel 418 of a signal encoder 402. Upon identifying the operating state of the system 400 as the first test operating state 500, the instrument component 416 may apply one or more activation signals to the switch component 410 via the switch controls 412 and 414 to couple the first terminal 452 of the test signal generator 406 to the first terminal 310 of the sensor 300.

[0075] The instrument component 416 may generate at least one activation signal 505 (e.g., depicted as a “SWITCH_P” signal) and apply it to the switches 456 and 458 of the switch component 410 via the first switch control 412. For example, the instrument component 416 may relay the activation signal 505 to the first switch control 412 to operate the first switch control 412 in the first test operating state 500. The first switch control 412 may, in turn, relay the activation signal 505 to each of the gate terminals of the field effect transistors in the switches 456 and 458. The activation signal 505 may specify that the switch 456 couple the second terminal 315 of the sensor 300 to one of the terminals of the input channel 418 of the signal encoder 402 via the switch 456. The activation signal 505 may also specify that the switch 458 couple the second terminal 315 of the sensor 300 to the same terminal of the input channel 418 of the signal encoder 402 via the switch 456.

[0076] At the same time as the activation signal 505 is applied (e.g., within nanoseconds or microseconds), the instrument component 416 can generate at least one activation signal 510 (e.g., depicted as a "SWITCH_N" signal) and apply it to the switches 460 and 462 of the switch component 410 via the second switch control 414. For example, the instrument component 416 can relay the activation signal 510 to the second switch control 414 to operate the second switch control 414 in the first test operating state 050. The second switch control 414 can, in turn, relay the activation signal 510 to each of the gate terminals of the field effect transistors in the switches 460 and 462. The activation signal 510 can specify that the switch 460 connect the first terminal 452 of the test signal generator 406 to the first terminal 310 of the sensor 300. The activation signal 510 can also specify that the switch 462 connect the second terminal 454 of the test signal generator 406 to one of the terminals of the input channel 418 of the signal encoder 402. The terminal of input channel 418 coupled via switch 460 may be different than the terminal of input channel 418 coupled via switch 458 (eg, as depicted).

[0077] By applying activation signals 505 and 510, the switch component 410 may form a first path 525 and a second path 530 between the test signal generator 406 and the signal encoder 402 through the sensor 300, the switch component 410 itself, and the input filter network 404, etc. The first path 525 may define an electrical connection between the first terminal 452 of the test signal generator 406, through the switch 460 of the switch component 410, the first terminal 310 of the sensor 300, the second terminal 315 of the sensor 300, the switches 456 and 458 of the switch component 410, the input filter network 404, and then to one of the terminals of the input channel 418 at the signal encoder 402. The second path 530 may define an electrical connection between the second terminal 454 of the test signal generator 406, through the switch 462 of the switch component 410, the input filter network 404, and then to the opposite terminal of the input channel 418 at the signal encoder 402.

[0078] In conjunction with applying the activation signals 505 and 510, the instrument component 416 may generate at least one control signal 515 and provide it to the test signal generator 406. The control signal 515 may indicate a state of the test signal generator 406, such as an active state (also referred to herein as an on state) or an inactive state (also referred to herein as an off state). When the operating state of the system 400 is identified as an abnormal operating state, the instrument component 416 may generate the control signal 515 to indicate the state of the test signal generator 406 as an active state. Otherwise, when the operating state of the system 400 is identified as an abnormal operating state, the instrument component 416 may generate the control signal 515 to indicate the state of the test signal generator 406 as an inactive state. Additionally, the instrument component 416 may generate the control signal 515 to include timing data (or instructions) for generating at least one test signal 535 to measure the operating characteristics of the sensor 300 (or hydrophone channel). The timing data of the control signal 515 may be a digital signal. The timing data may specify or define characteristics of the test signal 535 generated by the test signal generator 406 , such as amplitude, period, frequency, duration, signal waveform, etc. Along with generation, the instrument component 416 may provide a control signal 515 to the test signal generator 406 .

[0079] After receiving from the instrument component 416, the test signal generator 406 can parse the control signal 515. When parsing the control signal 515, the test signal generator 406 can identify a specified state. When the specified state is identified as inactive, the test signal generator 406 can limit or stop, or can not generate any test signal 535 sent by the sensor 300. On the other hand, when the specified state is identified as active, the test signal generator 406 can parse and identify the timing data of the control signal 515. The test signal generator 406 can generate the test signal 535 according to the timing data of the control signal 515. The test signal 535 can be used to measure the operating characteristics of the sensor 300 (or hydrophone channel), such as impedance. The test signal generator 406 can generate the test signal 535 to have the characteristics specified by the control signal 515, such as amplitude, period, frequency, duration, and signal waveform. The amplitude of the test signal 535 has a maximum value of 635V+ / -1.25V. The frequency of the test signal 535 may range from 2048 milliseconds to 4 milliseconds. The signal waveform of the test signal 535 may include a sawtooth wave, a sine wave, a square wave, a triangle wave, a linear chirp, a geometric chirp, and the like.

[0080] By generating according to the control signal 515, the test signal generator 406 can send, transmit or provide the test signal 535 via the first path 525 (or the second path 530). In addition, by applying the activation signals 505 and 510, the switch component 410 can route the test signal 535 from the test signal generator 406 through the first terminal 310 of the sensor 300, then through the second terminal 315 of the sensor 300, and then to one of the terminals of the input channel 418 of the signal encoder 402 (e.g., through the first path 525 as depicted). Upon arrival of the test signal 535 having passed through the first path 525, the signal encoder 402 can convert the test signal 535 from the analog domain to the digital domain, and can generate a composite signal 540. The composite signal 540 can be generated by the signal encoder 402 using the same function used to generate the signal 468. The composite signal 540, when received by the signal encoder 402, can be a digital domain representation of the test signal 535 and can include timing data corresponding to the test signal 535 in the digital domain. Via output channel 430 , signal encoder 402 may provide or relay composite signal 540 to instrument component 416 or the like.

[0081] By applying activation signals 505 and 510 and control signal 515, instrument component 416 can receive or identify composite signal 540 output via output channel 430 of signal encoder 402. Using composite signal 540, instrument component 416 can determine the operating characteristics of sensor 300 (or hydrophone channel). In determining the operating characteristics, instrument component 416 can compare the timing data of control signal 515 used to generate test signal 535 with the timing data of composite signal 540. Through comparison, instrument component 416 can calculate the impedance of sensor 300, such as resistance (e.g., as modeled by resistor 365), capacitance (e.g., as modeled by capacitor 360), and inductance.

[0082] The instrument component 416 can also convert the timing data of both the control signal 515 and the synthesized signal 540 into a frequency domain representation. Based on comparing the frequency domain representations, the instrument component 416 can determine the frequency response of the sensor 300. When calculating the impedance or frequency response of the sensor 300, the instrument component 416 can calculate the predetermined impedance (e.g., known from manufacturing specifications) of other components of the system 400 (such as the impedance library 408, the switches 456-462 of the switch component 410, the input filter network 404, and the internal components of the signal encoder 402 and the test signal generator 406). The system 400 can configure the DAC unit 442 to output a 0.488 Hz sine wave with a peak value of 5V between 452 and 454. The switch 460 can be configured to connect the test signal 535 to the sensor 300 via the first terminal 310. The switches 456 and 458 can be configured to transmit the signal received from the other side of the hydrophone to the first path 525 and the input of the signal encoder 402 through the second terminal 315. Switch 462 may be configured to connect terminals 452 and 454 to opposite polarity inputs of signal encoder 402. Data samples may be collected by instrumentation component 416.

[0083] The instrument component 416 can calculate the RMS amplitude of the collected data and can assign the RMS amplitude to V ADC The expected signal amplitude expected by the DAC unit 442 with the settings used is assigned to V TS The above steps can be repeated by exchanging the behavior of switch pairs 460 / 462 and 456 / 458. H If the calculated value is outside the acceptable range, the hydrophone may be flagged.

[0084] Using the calculated impedance, the instrument component 416 can determine whether the sensor 300 is operating properly. The instrument component 416 can compare the measured impedance of the sensor 300 with a threshold value. The threshold value can calibrate the expected value of the impedance in a properly operating hydrophone channel (including the sensor 300), and can range between 20-40 MΩ. When the difference is greater than the threshold value, the instrument component 416 can determine that the sensor 300 is not operating properly. On the other hand, when the difference is less than or equal to the threshold value, the instrument component 416 can determine that the sensor 300 is operating properly. The instrument component 416 can transmit or communicate the test state (e.g., the first test operating state 500), the determined impedance, and the determination of whether the sensor 300 is operating properly via the transceiver 240 of the housing 200 of the device 140.

[0085] in, Figure 6 A circuit diagram of a system 400 for measuring hydrophone impedance in a second test operating state 600 is depicted. The second test operating state 600 may facilitate measuring an operating characteristic of the sensor 300 in one path or direction. The second test operating state 600 may specify that the first terminal 452 of the test signal generator 406 is coupled to the second terminal 315 of the sensor 300. The second test operating state 600 may also specify that the second terminal 454 of the test signal generator 406 is coupled to one of the terminals of the input channel 418 of the signal encoder 402. Upon identifying the operating state of the system 400 as the second test operating state 600, the instrument component 416 may apply one or more activation signals to the switch component 410 via the switch controls 412 and 414 to couple the first terminal 452 of the test signal generator 406 to the second terminal 315 of the sensor 300.

[0086] The instrument component 416 can generate at least one activation signal 605 (e.g., depicted as a "SWITCH_P" signal) and apply it to the switches 456 and 458 of the switch component 410 via the first switch control 412. For example, the instrument component 416 can relay the activation signal 605 to the first switch control 412 to operate the first switch control 412 in the second test operating state 600. The first switch control 412 can, in turn, relay the activation signal 605 to each of the gate terminals of the field effect transistors in the switches 456 and 458. The activation signal 605 can specify that the switch 456 couple the second terminal 315 of the sensor 300 to the first terminal 452 of the test signal generator 406 via the switch 456 itself. The activation signal 605 can also specify that the switch 458 couple the second terminal 454 of the test signal generator 406 to one of the terminals of the input channel 418 of the signal encoder 402 via the switch 458 itself.

[0087] At the same time as the activation signal 605 is applied (e.g., within nanoseconds or microseconds), the instrument component 416 can generate at least one activation signal 610 (e.g., depicted as a "SWITCH_N" signal) and apply it to the switches 460 and 462 of the switch component 410 via the second switch control 414. For example, the instrument component 416 can relay the activation signal 610 to the second switch control 414 to operate the second switch control 414 in the second test operating state 600. The second switch control 414 can, in turn, relay the activation signal 610 to each of the gate terminals of the field effect transistors in the switches 460 and 462. The activation signal 610 can specify that the switch 460 connect the first terminal 310 of the sensor 300 to one of the terminals of the input channel 418 of the signal encoder 402 via the switch 462. The activation signal 610 can also specify that the switch 462 connect the first terminal 310 of the sensor 300 to the same terminal of the input channel 418 of the signal encoder 402 via the switches 460 and 462. The terminal of input channel 418 coupled via switch 460 may be different than the terminal of input channel 418 coupled via switch 458 (eg, as depicted).

[0088] By applying activation signals 605 and 610, switch component 410 may form a first path 625 and a second path 630 between test signal generator 406 and signal encoder 402 through sensor 300, switch component 410 itself, and input filter network 404, etc. First path 625 may define an electrical connection between first terminal 452 of test signal generator 406, through switch 456, second terminal 315 of sensor 300, first terminal 310 of sensor 300, switches 460 and 462 of switch component 410, input filter network 404, and then to one of the terminals of input channel 418 at signal encoder 402. Second path 630 may define an electrical connection between second terminal 454 of test signal generator 406, through switch 458 of switch component 410, input filter network 404, and then to the opposite terminal of input channel 418 at signal encoder 402.

[0089] In conjunction with applying the activation signals 605 and 610, the instrument component 416 may generate at least one control signal 615 and provide it to the test signal generator 406. The control signal 615 may indicate a state of the test signal generator 406, such as an active state (also referred to herein as an on state) or an inactive state (also referred to herein as an off state). When the operating state of the system 400 is identified as an abnormal operating state, the instrument component 416 may generate the control signal 615 to indicate the state of the test signal generator 406 as an active state. Otherwise, when the operating state of the system 400 is identified as an abnormal operating state, the instrument component 416 may generate the control signal 615 to indicate the state of the test signal generator 406 as an inactive state. Additionally, the instrument component 416 may generate the control signal 615 to include timing data (or instructions) for generating at least one test signal 635 to measure the operating characteristics of the sensor 300 (or hydrophone channel). The timing data of the control signal 615 may be a digital signal. The timing data may specify or define characteristics of the test signal 635 generated by the test signal generator 406 , such as amplitude, period, frequency, duration, signal waveform, etc. Along with generation, the instrument component 416 may provide a control signal 615 to the test signal generator 406 .

[0090] After receiving from the instrument component 416, the test signal generator 406 can parse the control signal 615. When parsing the control signal 615, the test signal generator 406 can identify a specified state. When the specified state is identified as inactive, the test signal generator 406 can limit or stop, or can not generate any test signal 635 sent by the sensor 300. On the other hand, when the specified state is identified as active, the test signal generator 406 can parse and identify the timing data of the control signal 615. The test signal generator 406 can generate the test signal 635 according to the timing data of the control signal 615. The test signal 635 can be used to measure the operating characteristics of the sensor 300 (or hydrophone channel), such as impedance. The test signal generator 406 can generate the test signal 635 to have the characteristics specified by the control signal 615, such as amplitude, period, frequency, duration, and signal waveform. The amplitude of the test signal 635 can have a maximum value of 635V+ / -1.25V. The frequency of the test signal 635 may range from 2048 milliseconds to 4 milliseconds. The signal waveform of the test signal 635 may include a sawtooth wave, a sine wave, a square wave, a triangle wave, a linear chirp, a geometric chirp, and the like.

[0091] By generating according to the control signal 615, the test signal generator 406 can send, transmit or provide the test signal 635 via the first path 625 (or the second path 630). In addition, by applying the activation signals 605 and 610, the switch component 410 can route the test signal 635 from the test signal generator 406 through the second terminal 315 of the sensor 300, then through the first terminal 310 of the sensor 300, and then to one of the terminals of the input channel 418 of the signal encoder 402 (e.g., through the first path 625 as depicted). Upon arrival of the test signal 635 that has passed through the first path 625, the signal encoder 402 can convert the test signal 635 from the analog domain to the digital domain, and can generate a composite signal 640. The composite signal 640 can be generated by the signal encoder 402 using the same function used to generate the signal 468. The composite signal 640, when received by the signal encoder 402, can be a digital domain representation of the test signal 635 and can include timing data corresponding to the test signal 635 in the digital domain. Via output channel 430 , signal encoder 402 may provide or relay composite signal 640 to instrument component 416 or the like.

[0092] By applying activation signals 605 and 610 and control signal 615, instrument component 416 can receive or identify composite signal 640 output via output channel 430 of signal encoder 402. Using composite signal 640, instrument component 416 can determine the operating characteristics of sensor 300 (or hydrophone channel). In determining the operating characteristics, instrument component 416 can compare the timing data of control signal 615 used to generate test signal 635 with the timing data of composite signal 640. Through comparison, instrument component 416 can calculate the impedance of sensor 300, such as resistance (e.g., as modeled by resistor 365), capacitance (e.g., as modeled by capacitor 360), and inductance.

[0093] The instrument component 416 can also convert the timing data of both the control signal 615 and the synthesized signal 640 into a frequency domain representation. Based on comparing the frequency domain representations, the instrument component 416 can determine the frequency response of the sensor 300. When calculating the impedance or frequency response of the sensor 300, the instrument component 416 can calculate the predetermined impedances (e.g., known from manufacturing specifications) of other components of the system 400 (such as the impedance library 408, the switches 456-462 of the switch component 410, the input filter network 404, and the internal components of the signal encoder 402 and the test signal generator 406, etc.).

[0094] Using the calculated impedance, the instrument component 416 can determine whether the sensor 300 is operating properly. The instrument component 416 can compare the measured impedance of the sensor 300 with a threshold value. The threshold value can calibrate the expected value of the impedance in a properly operating hydrophone channel (including the sensor 300), and can range between 20-40 MΩ. When the difference is greater than the threshold value, the instrument component 416 can determine that the sensor 300 is not operating properly. On the other hand, when the difference is less than or equal to the threshold value, the instrument component 416 can determine that the sensor 300 is operating properly. The instrument component 416 can transmit or communicate the test state (e.g., the second test operating state 600), the determined impedance, and the determination of whether the sensor 300 is operating properly via the transceiver 240 of the housing 200 of the device 140.

[0095] By setting the system 400 to the first test operating state 500 and the second test operating state 600, the instrument component 416 can perform a bipolar test when determining the impedance of the sensor 300 (or hydrophone channel). The first test operating state 500 can be performed after or before the second test operating state 600. Similarly, the determination of the impedance of the sensor 300 in the first test operating state 500 can be performed after or before the determination of the impedance of the sensor 300 in the second test operating state 600. Because the test signal generator 406 can be connected in series with the sensor 300 and the signal encoder 402 via the input filter network 404, the system 400 can test and measure the impedance of the hydrophone channel in two directions (e.g., paths 525 and 625). This configuration can allow for a higher sensitivity (ranging from 0Ω to 20MΩ) in the leakage resistance of the measured sensor 300 and a lower frequency range (ranging from 0.1 Hz to 50 Hz) in the test signals 535 and 635 to measure the impedance.

[0096] By performing the two test operating states 500 and 600, the instrument component 416 can compare the impedance of the sensor 300 tested in the first test operating state 500 with the impedance of the sensor 300 in the second test operating state 600. By comparing, the instrument component 416 can calculate or determine the difference between the determined impedances. In addition, the instrument component 416 can determine whether the sensor 300 (or the hydrophone channel) is unbalanced by comparing the difference with a threshold. The threshold can describe a normally operating hydrophone (including the sensor 300) and can range between 10-30 MΩ. When the difference is greater than the threshold, the instrument component 416 can determine that the sensor 300 is unbalanced. On the other hand, when the difference is less than or equal to the threshold, the instrument component 416 can determine that the sensor 300 is balanced. The instrument component 416 can transmit or transmit the determined impedance difference and the determination of whether the sensor 300 is balanced via the transceiver 240 of the housing 200 of the device 140.

[0097] Figure 7 A graph 700 depicts the input magnitude response of two example hydrophone channels (hydrophone "A" and hydrophone "B") under simulated conditions. The simulated conditions of graph 700 may include a 10nF capacitor and a 1TΩ parallel resistor. As depicted, the amplitude response of the two hydrophones may be similar, but hydrophone "A" may have a 1.2dB insertion loss that is not noticeable in hydrophone "B".

[0098] Figure 8 A graph 800 of the input signal versus the leakage resistance of a hydrophone channel under simulated conditions is depicted. In a properly functioning hydrophone, the signal level at the input of the signal encoder may be the same as an open circuit input. The simulated conditions may include another method for testing the impedance of a hydrophone channel, wherein the impedance of the hydrophone channel is measured in relation to the impedance of the hydrophone channel. Figures 4 to 6 As opposed to the series connection in the , the test signal generator can be connected in parallel. When the sensors are connected in parallel, the signal encoder input can be used largely as a voltage divider between the test signal generator output impedance (about 300Ω) and the parallel combination of the hydrophone and channel inputs (typically MΩ). The output impedance of the test signal generator can be about 5Ω. In this method using a 31.25Hz test signal, changes in signal level can be easily detected only when the leakage reaches 100kΩ.

[0099] Fig. 9 A graph 900 of input signal frequency versus leakage resistance of a hydrophone channel under simulated conditions is depicted. The simulated conditions may include using the system 400 with a test signal generator coupled in series with the hydrophone channel. In this manner, defective channels having high impedance or low impedance may now be identified. The center grouping of the depicted lines may indicate propagation due to variations of a properly functioning hydrophone meeting expected behavior. The upper line may represent a defective hydrophone due to a low impedance with a leakage resistance of 1 MΩ. The lower line may represent a defective hydrophone due to a high impedance without an attached hydrophone.

[0100] Fig.10 A graph 1000 of input signal versus impedance of a hydrophone channel under simulated conditions is depicted. The depicted simulation results can be used to determine the maximum impedance of a properly functioning hydrophone. The simulated conditions can include using system 400, where the test signal has a frequency of 0.488 Hz, where the hydrophone capacitance has three different values: 8.5 nF, 10 nF, and 11.5 nF. For each capacitance value, leakage resistance values ​​from 10 GΩ to 1 MΩ, 0, and ∞ were experienced. A third order equation can be used to characterize the behavior:

[0101]

[0102] in:

[0103] A3=1317561.35864472

[0104] A2=-8143282.26893616

[0105] A1=20941671.7630004

[0106] A0=-18697085.9892959

[0107] This diagram shows the effective hydrophone impedance, the capacitor X in parallel with the leakage resistor C The relationship between the voltage at the signal encoding input. The resulting range of hydrophone impedance is from 0 MΩ to about 38 MΩ. According to simulations, the maximum impedance of a properly functioning hydrophone can be 40 MΩ. The impedance of the hydrophone at 0.488 Hz (X C ) is 28.3MΩ to 38.3MΩ over a capacitance range of 10nF + / -15%. An open circuit hydrophone input results in a V of approximately 0.146 (-16.72dB) ADC / V TS ratio, which will be converted into an impedance of 166MΩ.

[0108] Fig.11 A graph 1100 of input signal versus impedance of a hydrophone channel under simulated conditions is depicted. The depicted simulation results may be used to determine the minimum impedance of a properly functioning hydrophone. The simulated conditions may include using the system 400 with a test signal having frequencies with different values ​​of hydrophone capacitance and leakage resistance: 10nF and 1TΩ, 10nF and 1GΩ, 10nF and 270MΩ, and 10nF and 20MΩ. As shown, the tolerance of the hydrophone sensitivity is + / -1dB. A 20MΩ leakage may result in an impedance of 17.05MΩ (-11.963dB & 0.252249V / V), which is in contrast to the simulation that returned a result of 18.4MΩ for this signal level. According to the simulation, the minimum impedance of a properly functioning hydrophone may be 18.4MΩ. In normal acquisition, a 20MΩ leakage resistance on a phone may result in a 1dB loss at 3Hz. The hydrophone may have a sensitivity tolerance of + / -1dB. A 20MΩ leakage resistor may result in a 1dB sensitivity loss. The impedance of a 20nF hydrophone in parallel with the 20MΩ leakage resistor is 17MΩ. The measured hydrophone impedance of 17MΩ may be the pass-fail limit.

[0109] Based on simulations, the impedance limit of a properly functioning hydrophone can range between 20MΩ and 40MΩ when "SWITCH_N" or "SWITCH_P" is activated for testing. Only when the FET on one terminal of the sensor is activated, the connection from that terminal to ground may result in an undesirable impedance. To detect such an unbalanced ground fault, the sensor can be tested in both polarities as described in detail herein.

[0110] in, Fig.12 A flow chart of a method 1200 for measuring hydrophone impedance is depicted. Figures 1 to 6 as well as Fig.14 The method 1200 may be performed or implemented by any of the components described in the electronic circuit or system 400. The method 1200 may include generating a test signal 535 or 635 (1205). The test signal generator 406 of the electronic circuit or system 400 may generate the test signal 535 or 635 to measure the impedance of the sensor 300, such as resistance, capacitance, or inductance. The test signal 535 or 635 may have one or more characteristics defined or set via a control signal 515 or 615 from the instrument component 416. The characteristics of the test signal 535 or 635 may include, for example, amplitude, period, frequency, duration, and signal waveform. Once generated, the test signal generator 406 may transmit or send the test signal 535 or 635.

[0111] The method 1200 may include setting an operating state (1210). The operating state may define or specify the flow of electrical signals through the system 400 from the sensor 300 to the signal encoder 402. The operating state may include a normal operating state, a first test operating state 500, and a second test operating state 600. The operating state may be set via the instrument component 416 to measure the impedance of the sensor 300.

[0112] The method 1200 may include determining an operating state (1215). The instrument component 416 may identify or determine an operating state set for the system 400. The instrument component 416 may determine the operating state to be a normal operating state. In the normal operating state, the instrument component 416 may apply an activation signal to the switch component 410 via the switch controls 412 and 414 to disconnect the test signal generator 406 from the sensor 300 and the signal encoder 402. The electrical signal 325 from the sensor 300 may flow through the input filter network 404 to the signal encoder 402 without passing through the test signal generator 406.

[0113] The method 1200 may include routing a test signal 535 through a path 525 in a hydrophone channel when the operating mode is determined to be a first test operating state 500 (1220). In the first test operating state 500, the instrument component 416 may apply activation signals 505 and 510 to the switch component 410 via the switch controls 412 and 414. By applying the activation signals 505 and 510, the switch component 410 may route the test signal 535 from the test signal generator 406 through the first terminal 310 of the sensor 300, the second terminal 315 of the sensor 300, and then to the signal encoder 402 via the input filter network 404. The test signal generator 406 may also generate the test signal 535 according to the specification of the control signal 515 from the instrument component 416.

[0114] The method 1200 may include routing a test signal 635 through a path 625 in a hydrophone channel when the operating mode is determined to be the second test operating state 600 (1225). In the second test operating state 600, the instrument component 416 may apply activation signals 605 and 610 to the switch component 410 via the switch controls 412 and 414. By applying the activation signals 605 and 610, the switch component 410 may route the test signal 635 from the test signal generator 406 through the second terminal 315 of the sensor 300, then through the first terminal 310 of the sensor 300, and then to the signal encoder 402 via the input filter network. The test signal generator 406 may also generate the test signal 635 according to the specification of the control signal 615 from the instrument component 416.

[0115] The method 1200 may include determining the impedance of the hydrophone (1230). The instrument component 416 may identify the synthesized signal 540 or 640 output by the signal encoder 402. The instrument component 416 may compare the timing data in the synthesized signal 540 or 640 with the timing data of the control signal 515 or 615 used to generate the test signal 535 or 635. Based on the comparison, the instrument component 416 may calculate or determine the impedance of the sensor 300 (or hydrophone channel). The instrument component 416 may also use the determination of the impedance in the first test operating state 500 and the second test operating state 600 to determine whether the sensor 300 is operating properly and whether the sensor 300 is balanced.

[0116] in, Fig.13A flow chart of a method 1300 of providing an apparatus for measuring hydrophone impedance is depicted. The method 1300 may include providing an electronic circuit or system 400 to measure the hydrophone impedance (1350). The electronic circuit or system 400 may be disposed in the housing 200 of the apparatus 140 to perform seismic operations in deep water 105. The system 400 may include a sensor 300. The sensor 300 may convert an acoustic signal 320 propagating through the water 105 into an electrical signal 325. The system 400 may include an input filter network 404 coupled in parallel with the sensor 300. The input filter network 404 may perform a filtering operation on the electrical signal 325 as the electrical signal 325 passes through the input filter network 404. The system 400 may include a signal encoder 402 coupled in parallel with the input filter network 404 to receive the electrical signal 325 from the sensor 300. The signal encoder 402 may convert the electrical signal 325 into a synthesized signal 468 corresponding to a digital representation of the electrical signal 325.

[0117] The system 400 to be provided may include a test signal generator 406 that may be coupled in series with the sensor 300 and the signal encoder 402 via an input filter network 404. The test signal generator 406 may generate a test signal 535 or 635 to be transmitted via the sensor 300 (and the hydrophone channel). The system 400 may include a switch component 410 coupled in series between the sensor 300 and the signal encoder 402 via the input filter network 404. Based on an operating state, the switch component 410 may control the coupling of the test signal generator 406 to the sensor 300 and route the electrical signal through the system 400. When in a normal operating state, the switch component 410 may route the electrical signal 325 from the sensor 300 to the signal encoder 402 via the input filter network 404.

[0118] When in the first test operating state 500, the switch component 410 can route the test signal 535 from the test signal generator 406 through the first terminal 310 of the sensor 300, then to the second terminal 315 of the sensor 300, and then to the signal encoder 402 via the input filter network 404. When in the second test operating state 600, the switch component 410 can route the test signal 635 from the test signal generator 406 through the second terminal 315 of the sensor 300, then through the first terminal 310 of the sensor 300, and then to the signal encoder 402. The system 400 to be provided may include an instrument component 416. The instrument component 416 can control the operation of the switch component 410 via the switch controls 412 and 416. The instrument component 416 can also determine the impedance of the hydrophone channel based on the synthesized signal 540 or 640 received via the signal encoder 402 during the first test operating state 500 and the second test operating state 600, respectively.

[0119] Fig.14 Describes the methods used to implement Figures 4 to 6 , Fig.12 as well as Fig.13 1400 is a block diagram of the architecture of a computing system for the various elements of the system depicted in FIG. 1400 (e.g., signal encoder 402, input filter network 404, test signal generator 406, switch controls 412 and 414, and instrument component 416) and methods. The computing system 1400 includes a bus 1405 or other communication component for transmitting information and a processor 1410 or processing circuit connected to the bus 1405 for processing information. The computing system 1400 may also include one or more processors 1410 or processing circuits connected to the bus for processing information. The computing system 1400 also includes a main memory 1415 such as a random access memory (RAM) or other dynamic storage device connected to the bus 1405 for storing information and instructions executed by the processor 1410. The main memory 1415 may also be used to store seismic data, binning function data, images, reports, tuning parameters, executable code, temporary variables, or other intermediate information during the execution of instructions by the processor 1410. Computing system 1400 may further include a read only memory (ROM) 1420 or other static storage device coupled to bus 1405 for storing static information and instructions for processor 1410. A storage device 1425, such as a solid-state device, magnetic disk, or optical disk, is coupled to bus 1405 for persistent storage of information and instructions.

[0120] The computing system 1400 may be coupled to a display 1435 or display device, such as a liquid crystal display or an active matrix display, via the bus 1405 for displaying information to a user. An input device 1430, such as a keyboard including alphanumeric and other keys, may be coupled to the bus 1405 for communicating information and command selections to the processor 1410. The input device 1430 may include a touch screen display 1435. The input device 1430 may also include a cursor control, such as a mouse, a trackball, or cursor direction keys, for communicating direction information and command selections to the processor 1410 and for controlling cursor movement on the display 1435.

[0121] The processes, systems, and methods described herein may be implemented by the computing system 1400 in response to the processor 1410 executing an arrangement of instructions contained in the main memory 1415. Such instructions may be read into the main memory 1415 from another computer-readable medium such as the storage device 1425. The execution of the arrangement of instructions contained in the main memory 1415 causes the computing system 1400 to perform the illustrative processes described herein. One or more processors in a multi-processing arrangement may also be used to execute the instructions contained in the main memory 1415. In some embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement the illustrative implementations. Therefore, the embodiments are not limited to any specific combination of hardware circuitry and software.

[0122] Although already Fig.14 An example computing system is described in the specification, but embodiments of the subject matter and functional operations described in this specification may be implemented in other types of digital electronic circuits, or in computer software, firmware, or hardware (including the structures disclosed in this specification and their structural equivalents), or in a combination of one or more of them.

[0123] The subject matter and embodiments of the operations described in this specification may be implemented in digital electronic circuits, or in computer software, firmware or hardware (including the structures disclosed in this specification and their structural equivalents), or in a combination of one or more of them. The subject matter described in this specification may be implemented as one or more computer programs (e.g., one or more circuits of computer program instructions) encoded on one or more computer storage media for execution by a data processing device or for controlling the operation of the data processing device. Alternatively or additionally, program instructions may be encoded on an artificially generated propagation signal (e.g., a machine-generated electrical signal, optical signal, or electromagnetic signal) that is generated to encode information for transmission to an appropriate receiver device for execution by the data processing device. The computer storage medium may be a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination of one or more of them, or may be included in a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination of one or more of them. In addition, although a computer storage medium is not a propagation signal, a computer storage medium may be a source or destination of computer program instructions encoded in an artificially generated propagation signal. The computer storage medium can also be, or be included in, one or more separate components or media (eg, multiple CDs, disks, or other storage devices).

[0124] The operations described in this specification can be performed by a data processing device on data stored on one or more computer-readable storage devices or received from other sources. The term "data processing device" or "computing device" covers various devices, equipment and machines for processing data, such as programmable processors, computers, systems on chips, or multiple programmable processors, computers, systems on chips, or a combination of the foregoing. The device may include a dedicated logic circuit, such as an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). In addition to hardware, the device may also include code for creating an execution environment for the computer program in question, for example, code constituting a processor firmware, a protocol stack, a database management system, an operating system, a cross-platform runtime environment, a virtual machine, or a combination of one or more of them. The device and the execution environment can implement a variety of different computing model infrastructures, such as web services, distributed computing, and grid computing infrastructures.

[0125] A computer program (also referred to as a program, software, software application, script, or code) may be written in any form of programming language, including compiled or interpreted, declarative or procedural, and it may be deployed in any form, including as a stand-alone program or as a circuit, component, subroutine, object, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program may be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple collaborative files (e.g., files storing one or more circuits, subroutines, or portions of code). A computer program may be deployed to execute on one computer or on multiple computers located at one site or distributed across multiple sites and interconnected by a communications network.

[0126] Processors suitable for executing computer programs include, for example, any one or more processors of a microprocessor and a digital computer. The processor may receive instructions and data from a read-only memory or a random access memory or both. The elements of a computer are a processor for performing actions according to instructions and one or more memory devices for storing instructions and data. The computer may include one or more mass storage devices (such as magnetic disks, magneto-optical disks, or optical disks) for storing data, or may be operably connected to receive data from or transmit data to the one or more mass storage devices, or both. The computer does not have to have such a device. In addition, the computer may be embedded in another device, such as a personal digital assistant (PDA), a global positioning system (GPS) receiver, or a portable storage device (e.g., a universal serial bus (USB) flash drive), to name just a few examples. Devices suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and memory devices, including, for example: semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks, such as internal hard disks or removable disks; magneto-optical disks; and CD ROM and DVD-ROM disks. The processor and memory may be supplemented by or incorporated into a dedicated logic circuit.

[0127] To provide interaction with a user, embodiments of the subject matter described in this specification may be implemented on a computer having a display device (e.g., a CRT (cathode ray tube) monitor or an LCD (liquid crystal display) monitor) for displaying information to the user, and a keyboard and a pointing device (e.g., a mouse or a trackball) through which the user can provide input to the computer. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback, such as visual feedback, auditory feedback, or tactile feedback; and input from the user may be received in any form, including sound, voice, or tactile input.

[0128] The embodiments described herein can be implemented in any of a variety of ways, including, for example, using hardware, software, or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or set of processors, whether the processor is provided in a single computer or distributed among multiple computers.

[0129] In addition, the computer can have one or more input devices and output devices. These devices can be used to present a user interface in particular. Examples of output devices that can be used to provide a user interface include a printer or display screen for visual presentation of the output, and a loudspeaker or other sound generating device for audible presentation of the output. Examples of input devices that can be used for a user interface include a keyboard and a pointing device such as a mouse, a touch pad, and a digitized graphic input board. As another example, the computer can receive input information by voice recognition or in other audible formats.

[0130] Such computers may be interconnected by one or more networks in any suitable form, including local or wide area networks, such as enterprise networks and intelligent networks (IN) or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol, and may include wireless networks, wired networks, or fiber optic networks.

[0131] A computer for implementing at least a portion of the functions described herein may include a memory, one or more processing units (also referred to herein as "processors"), one or more communication interfaces, one or more display units, and one or more user input devices. The memory may include any computer-readable medium, and may store computer instructions (also referred to herein as "processor executable instructions") for implementing the various functions described herein. The processing unit may be used to execute instructions. The communication interface may be connected to a wired or wireless network, a bus, or other communication device, and may therefore allow the computer to transmit communications to or receive communications from other devices. For example, a display unit may be provided to allow a user to view various information related to the execution of instructions. For example, a user input device may be provided to allow a user to manually adjust, select, input data or various other information, or interact with the processor in any of a variety of ways during the execution of instructions.

[0132] The various methods or processes outlined herein may be encoded as software that can be executed on one or more processors using any of a variety of operating systems or platforms. Additionally, such software may be written using any of a variety of suitable programming languages ​​or programming or scripting tools, and may also be compiled into executable machine language code or intermediate code that is executed on a framework or virtual machine.

[0133] In this regard, various inventive concepts may be implemented as a computer-readable storage medium (or multiple computer-readable storage media) (e.g., computer memory, one or more floppy disks, optical disks, optical discs, tapes, flash memory, circuit configurations in field programmable gate arrays or other semiconductor devices, or other non-volatile media or tangible computer storage media), which computer-readable storage medium is encoded with one or more programs that, when executed on one or more computers or other processors, perform methods that implement various embodiments of the solution discussed above. One or more computer-readable media may be transportable so that the one or more programs stored thereon can be loaded onto one or more different computers or other processors to implement various aspects of the present solution as discussed above.

[0134] The term "program" or "software" is used herein to refer to any type of computer code or computer executable instruction set that can be used to program a computer or other processor to implement various aspects of the embodiments as discussed above. The one or more computer programs that perform the methods of the present solution when executed need not reside on a single computer or processor, but can be distributed in a modular manner among multiple different computers or processors to implement various aspects of the present solution.

[0135] Computer executable instructions can be executed by one or more computers or other devices in various forms (such as program modules). Program modules can include routines, programs, objects, components, data structures, or other components that perform specific tasks or implement specific abstract data types. The functions of program modules can be combined or distributed as needed in various embodiments.

[0136] In addition, the data structure can be stored in a computer-readable medium in any suitable form. To simplify the description, the data structure can be shown as having fields that are related by position in the data structure. Such a relationship can also be achieved by assigning the fields with storage that conveys the relationship between the fields in a computer-readable medium. However, any suitable mechanism can be used to establish the relationship between the information in the fields of the data structure, including by using pointers, tags or other mechanisms to establish the relationship between data elements.

[0137] Any reference to an embodiment or element or action of the systems and methods herein in the singular may include an embodiment comprising a plurality of these elements, and any reference to any embodiment or element or action herein in the plural may include an embodiment comprising only a single element. References in the singular or plural are not intended to limit the currently disclosed systems or methods, their parts, actions or elements to a single configuration or multiple configurations. References to any action or element based on any information, action or element may include an embodiment in which the action or element is based at least in part on any information, action or element.

[0138] Any embodiment disclosed herein may be combined with any other embodiment, and references to "an embodiment," "some embodiments," "alternative embodiments," "various embodiments," or "one embodiment," etc. are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in conjunction with an embodiment may be included in at least one embodiment. These terms as used herein do not necessarily all refer to the same embodiment. Any embodiment may be combined with any other embodiment (inclusively or exclusively) in any manner consistent with the aspects and embodiments disclosed herein.

[0139] References to "or" may be interpreted as inclusive, such that any term described using "or" may indicate any of a single, more than one, and all of the terms described. References to at least one of a joint list of terms may be interpreted as inclusive or to indicate any of a single, more than one, and all of the terms described. For example, reference to "at least one of 'A' and 'B'" may include only 'A', only 'B', and both 'A' and 'B'. Such references used in conjunction with "including" or other open-ended terms may include additional items.

[0140] The systems and methods described herein may be implemented in other specific forms without departing from their characteristics.The above embodiments are illustrative rather than limiting of the described systems and methods.

[0141] Where a technical feature in the drawings, detailed description or any claim is followed by a reference numeral, the reference numeral has been included to increase the intelligibility of the drawings, detailed description and claims. Accordingly, the presence or absence of a reference numeral has no limiting effect on the scope of any claim element.

[0142] The systems and methods described herein may be implemented in other specific forms without departing from their characteristics. The above embodiments are illustrative rather than limiting of the described systems and methods. Therefore, the scope of the systems and methods described herein is indicated by the appended claims rather than the above description, and changes falling within the meaning and scope of the equivalents of the claims are included therein.

Claims

1. A system for measuring hydrophone impedance, comprising: A sensor for converting sound waves received via a liquid medium into an electrical signal, the sensor having a first polarity terminal and a second polarity terminal, the second polarity terminal having a polarity opposite to that of the first polarity terminal; a signal encoder connected to the sensor to receive the electrical signal converted by the sensor; a test signal generator coupled in series with the sensor and the signal encoder to generate a test signal to be sent through the sensor and the signal encoder, the test signal being used to measure the impedance of the sensor; as well as a switch component coupled in series with the sensor, the signal encoder and the test signal generator, the switch component having a first operating state and a second operating state, wherein the switch component is configured to: responsive to the switch member being set to the first operating state, routing the test signal from the test signal generator to the first polarity terminal of the sensor, through the second polarity terminal of the sensor and to the signal encoder, and responsive to the switch component being set to the second operating state, routing the test signal from the test signal generator to the second polarity terminal of the sensor, through the first polarity terminal of the sensor, and to the signal encoder; as well as An instrument component, including an impedance measurer, is coupled to the signal encoder and the test signal generator, wherein the instrument component is configured to: determining a first impedance of the sensor using the test signal and a first resultant signal output by the signal encoder in response to the test signal during the first operating state; and determining a second impedance of the sensor using the test signal and a second resultant signal output by the signal encoder in response to the test signal during the second operating state.

2. The system according to claim 1, wherein: The switch member has a third operating state, the switch member being operable to inhibit the test signal from being transmitted from the test signal generator to the sensor and the signal encoder in response to the switch member being set to the third operating state.

3. The system according to claim 1, wherein: The test signal generator has an active state and an inactive state, and the test signal generator is used to: generating the test signal to be sent through the sensor and the signal encoder in response to the test signal generator being set to the active state; and In response to the test signal generator being set to the inactive state, the test signal is restricted from being sent through the sensor and the signal encoder.

4. The system according to claim 1, wherein: The switch component includes a plurality of switches, each of the plurality of switches including: a first terminal coupled to one of the first polarity terminal and the second polarity terminal of the sensor to receive the electrical signal; a second terminal connected to the signal encoder to transmit the electrical signal or the test signal to the signal encoder; and The third terminal is connected to the switch control to receive an activation signal, wherein the activation signal identifies one of the first operating state and the second operating state.

5. The system according to claim 1, further comprising: A switch control is connected to the switch component, and the switch control is used to send an activation signal to the switch component, wherein the activation signal identifies one of the first operating state and the second operating state, and the receipt of the activation signal is used to cause the switch component to operate in one of the first operating state and the second operating state identified by the activation signal.

6. The system according to claim 1, wherein: The test signal generator is used for generating a plurality of test signals, each of the plurality of test signals having a set frequency to measure the impedance of the sensor at the set frequency, and the set frequency ranges from 0.1 Hz to 10 Hz.

7. The system according to claim 1, wherein: The test signal generator is configured to generate the test signal to be sent through the sensor and the signal encoder, the test signal being used to measure a leakage resistance of the sensor, the leakage resistance measured using the test signal ranging from 0Ω to 20MΩ.

8. The system according to claim 1, wherein: The instrument component is connected to the signal encoder and the test signal generator, and the instrument component is used to: identifying a first composite signal output by the signal encoder in response to the test signal during the first operating state; identifying a second composite signal output by the signal encoder in response to the test signal during the second operating state; and The impedance of the sensor is determined using the test signal, the first and second composite signals, and predetermined impedances of components between the sensor and the signal encoder.

9. The system of claim 1, further comprising: An input filter network is connected in series between the switch component and the signal encoder, the input filter network is connected to the test signal generator, and the input filter network is used to filter the signal from the sensor.

10. The system according to claim 1, wherein: The sensor includes a piezoelectric transducer for converting a pressure change in the liquid medium corresponding to the sound wave into the electrical signal.

11. The system according to claim 1, wherein: The test signal generator comprises: a digital-to-analog converter DAC, for converting a timing sequence into the test signal to measure the impedance of the sensor; and A plurality of field effect transistors (FETs) are connected to the DAC to connect the DAC in series between the sensor and the signal encoder.

12. A method for measuring hydrophone impedance, comprising: generating, by a test signal generator, a test signal to be sent through a sensor and a signal encoder to measure the impedance of the sensor, the sensor being used to convert an acoustic wave into an electrical signal, the sensor having a first polarity terminal and a second polarity terminal, the second polarity terminal having a polarity opposite to that of the first polarity terminal, the signal encoder being connected in series with the sensor to receive the electrical signal; in response to a switch component coupled in series with the sensor, the signal encoder, and the test signal generator being set to a first operating state, routing the test signal from the test signal generator to the first polarity terminal of the sensor, through the second polarity terminal of the sensor, and to the signal encoder by the switch component; and in response to the switch member being set to a second operating state, routing the test signal from the test signal generator to the second polarity terminal of the sensor, through the first polarity terminal of the sensor and to the signal encoder by the switch member, The bipolar test is performed by an instrument component, the instrument component including an impedance measurer coupled to the signal encoder and the test signal generator, wherein the instrument component is configured to: determining a first impedance of the sensor using the test signal and a first resultant signal output by the signal encoder in response to the test signal during the first operating state; and determining a second impedance of the sensor using the test signal and a second resultant signal output by the signal encoder in response to the test signal during the second operating state.

13. The method according to claim 12, comprising: In response to the test signal generator being set to an active state, generating, by the test signal generator, the test signal to be sent through the sensor and the signal encoder; and In response to the test signal generator being set to an inactive state, the test signal is restricted from being sent through the sensor and the signal encoder by the test signal generator.

14. The method according to claim 12, comprising: identifying, by the instrument component coupled to the test signal generator and the signal encoder, a first composite signal output by the signal encoder in response to the test signal during the first operating state; identifying, by the instrument component, a second composite signal output by the signal encoder in response to the test signal during the second operating state; and The impedance of the sensor is determined by the instrument component using the test signal, the first and second composite signals, and a predetermined impedance of a component between the sensor and the signal encoder.

15. The method according to claim 12, comprising: A plurality of test signals are generated by the test signal generator, each of the plurality of test signals having a set frequency to measure the impedance of the sensor at the set frequency, and the set frequency ranges from 0.1 Hz to 10 Hz.

16. The method according to claim 12, comprising: An activation signal is set to the switch component by a switch control connected to the switch component, the activation signal identifying one of the first operating state and the second operating state, and reception of the activation signal is used to cause the switch component to operate in one of the first operating state and the second operating state identified by the activation signal.

17. An apparatus for measuring seismic data, comprising: case; A hydrophone channel is disposed in the housing, and the hydrophone channel comprises: A sensor for converting sound waves received via a liquid medium into electrical signals; an input channel to a signal encoder, the input channel coupled in parallel with the sensor to receive the electrical signal from the sensor; and an input filter network connected in parallel between the sensor and the signal encoder to transmit the electrical signal received from the sensor to the signal encoder; and a test signal generator disposed in the housing, the test signal generator being connected in series with the hydrophone channel between the sensor and the input filter network, the test signal generator being used to generate a test signal to be sent through the hydrophone channel, the test signal being used to measure the impedance of the sensor; A switch component is disposed in the housing, the switch component is connected in series between the sensor of the hydrophone channel and the signal encoder, the switch component has a first operating state and a second operating state, and the switch component is used to: responsive to the switch member being set to the first operating state, routing the test signal from the test signal generator through the hydrophone channel in a first path, and responsive to the switch member being set to the second operating state, routing the test signal from the test signal generator through the hydrophone channel in a second path; and An instrument component, including an impedance measurer, is coupled to the signal encoder and the test signal generator, wherein the instrument component is configured to: A first impedance of the sensor is determined using the test signal and a first composite signal output by the signal encoder in response to the test signal during the first operating state; and a second impedance of the sensor is determined using the test signal and a second composite signal output by the signal encoder in response to the test signal during the second operating state.

18. The device according to claim 17, wherein: The instrument component is disposed in the housing, the instrument component is connected to the signal encoder and the test signal generator, and the instrument component is used for: identifying a first composite signal output by the signal encoder in response to the test signal during the first operating state; identifying a second composite signal output by the signal encoder in response to the test signal during the second operating state; and The impedance of the sensor is determined using the test signal, the first and second composite signals, and a predetermined impedance of the hydrophone channel.

19. The apparatus according to claim 17, comprising: The test signal generator is used to generate a plurality of test signals, each of the plurality of test signals having a set frequency to measure the impedance of the sensor at the set frequency, and the set frequency ranges from 0.1 Hz to 10 Hz.

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