Dual-frequency cw underwater acoustic signal conditioning circuit with automatic switching of filter and gain

Abstract

This application belongs to the field of underwater acoustic signal processing technology, and provides a dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain. It includes: a preamplifier module for amplifying the received raw underwater acoustic signal and outputting a signal to be conditioned; a low-frequency conditioning unit that is enabled when the signal to be conditioned contains effective low-frequency CW components and performs gain grading and filtering on the signal to be conditioned to output a low-frequency conditioned signal; a high-frequency conditioning unit that performs gain grading and high-frequency filtering on the signal to be conditioned to output a high-frequency conditioned signal when the signal to be conditioned contains effective high-frequency CW components; and an output module for outputting either the low-frequency conditioned signal or the high-frequency conditioned signal. The technical solution of this application can automatically select an appropriate filtering channel and gain factor based on the frequency and amplitude of the raw underwater acoustic signal.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of underwater acoustic signal processing, and specifically provides a dual-frequency CW underwater acoustic signal conditioning circuit capable of automatically switching filtering and gain. BACKGROUND

[0002] In the field of underwater acoustic detection, according to different application scenarios and tasks, it is often necessary to receive and process CW (Continuous Wave) underwater acoustic signals of specific frequencies. For example, when a three-dimensional imaging sonar is used to detect underwater objects or terrain, a CW signal with a frequency of 300K can be used for long-distance detection to search and locate in a large range, and a CW signal with a frequency of 600K can be used for close-range fine imaging to capture target details and accurate morphology. In the above application scenarios, the CW signal with a frequency of 300K can be referred to as a low-frequency CW signal, and the CW signal with a frequency of 600K can be referred to as a high-frequency CW signal. Accordingly, in the signal receiving and processing link, it is necessary to ensure that the signal conditioning circuit has good processing capability for low-frequency and high-frequency CW underwater acoustic signals.

[0003] At present, the common underwater acoustic conditioning circuits for processing low-frequency and high-frequency CW underwater acoustic signals mainly have the following schemes: according to the frequency of the actively transmitted signal and the amplitude of the received signal, manually selecting low-frequency and high-frequency gain filtering circuits and adjusting the gain multiple. This way has low gain adjustment accuracy and poor flexibility, and cannot realize effective judgment and automatic switching of the filtering circuit; a wideband filter is used for signal filtering. This filter allows signals in a relatively wide frequency range to pass through, but it cannot adaptively compensate for the attenuation of signals with specific frequencies; a CPU or other digital control module is used to realize gain control and filtering circuit switching of the relevant adjustment part through digital signal processing. However, this way requires additional computing resources and has high implementation cost. SUMMARY

[0004] To solve the problems existing in the prior art, the application provides a dual-frequency CW underwater acoustic signal conditioning circuit capable of automatically switching filtering and gain, comprising:

[0005] A preamplification module amplifies the received original underwater acoustic signal and outputs a to-be-conditioned signal;

[0006] A low-frequency conditioning unit is enabled when the to-be-conditioned signal contains an effective low-frequency CW component, and performs gain grading and low-frequency filtering on the to-be-conditioned signal based on the amplitude of the effective low-frequency CW component to output a low-frequency conditioned signal.

[0007] a high-frequency conditioning unit enabled when the effective high-frequency CW component is contained in the signal to be conditioned, and performing gain grading and high-frequency filtering on the signal to be conditioned based on the amplitude of the effective high-frequency CW component to output a high-frequency conditioning signal;

[0008] an output module configured to output the low-frequency conditioning signal or the high-frequency conditioning signal.

[0009] Further, the low-frequency conditioning unit comprises a low-frequency detection module, a low-frequency control quantity module, a low-frequency enabling module, a low-frequency gain module, and a low-frequency filtering module.

[0010] The low-frequency detection module is configured to convert the signal to be conditioned into a direct-current low-frequency component detection signal.

[0011] The low-frequency control quantity module is configured to generate a low-frequency control quantity signal based on the amplitude of the low-frequency component detection signal, wherein the low-frequency control quantity signal comprises a low-frequency enabling signal and a low-frequency gain grading signal.

[0012] The low-frequency enabling module is configured to enable or disable the low-frequency gain module based on the low-frequency enabling signal.

[0013] The low-frequency gain module is configured to perform gain grading on the signal to be conditioned based on the low-frequency gain grading signal in an enabled state.

[0014] The low-frequency filtering module is configured to perform low-frequency filtering on the signal output by the low-frequency gain module and output the low-frequency conditioning signal.

[0015] Further, the high-frequency conditioning unit comprises a high-frequency detection module, a high-frequency control quantity module, a high-frequency enabling module, a high-frequency gain module, and a high-frequency filtering module.

[0016] The high-frequency detection module is configured to convert the signal to be conditioned into a direct-current high-frequency component detection signal.

[0017] The high-frequency control quantity module is configured to generate a high-frequency control quantity signal based on the amplitude of the high-frequency component detection signal, wherein the high-frequency control quantity signal comprises a high-frequency enabling signal and a high-frequency gain grading signal.

[0018] The high-frequency enabling module is configured to enable or disable the high-frequency gain module based on the high-frequency enabling signal.

[0019] The high-frequency gain module is configured to perform gain grading on the signal to be conditioned based on the high-frequency gain grading signal in an enabled state.

[0020] The high-frequency filtering module is configured to perform high-frequency filtering on the signal output by the high-frequency gain module and output the high-frequency conditioning signal.

[0021] Further, the low-frequency control quantity module comprises a first low-frequency comparator, a second low-frequency comparator and a third low-frequency comparator.

[0022] The first low-frequency comparator is configured to compare the amplitude of the low-frequency component detection signal with a first low-frequency threshold voltage and output a comparison result, the second low-frequency comparator is configured to compare the amplitude of the low-frequency component detection signal with a second low-frequency threshold voltage and output a comparison result, and the third low-frequency comparator is configured to compare the amplitude of the low-frequency component detection signal with a third low-frequency threshold voltage and output a comparison result, wherein the first low-frequency threshold voltage, the second low-frequency threshold voltage and the third low-frequency threshold voltage increase in sequence.

[0023] The output end of the first low-frequency comparator is configured to output the low-frequency enable signal.

[0024] The output end of the second low-frequency comparator and the output end of the third low-frequency comparator are configured to output a two-bit binary low-frequency gain gear signal.

[0025] Further, the low-frequency gain module comprises a low-frequency amplifier and a low-frequency switching switch.

[0026] The negative input end of the low-frequency amplifier is configured to input the to-be-conditioned signal, the output end of the low-frequency amplifier is connected with the low-frequency filter module, and the low-frequency enable module is connected between the power supply of the low-frequency amplifier and the power supply port.

[0027] The low-frequency switching switch is feedback connected between the output end and the negative input end of the low-frequency amplifier, and the low-frequency switching switch switches the amplification multiple of the low-frequency amplifier to the to-be-conditioned signal based on the low-frequency gain gear signal.

[0028] Further, the low-frequency switching switch has three analog input ends, two digital input ends and one analog output end.

[0029] The three analog input ends of the low-frequency switching switch are connected with the negative input end of the low-frequency amplifier through resistors with different resistances, the analog output end of the low-frequency switching switch is connected with the output end of the low-frequency amplifier, and the two digital input ends of the low-frequency switching switch are configured to input the low-frequency gain gear signal.

[0030] The low-frequency switching switch selectively connects one of the three analog input ends and the analog output end based on the low-frequency gain gear signal.

[0031] Further, the high-frequency control quantity module comprises a first high-frequency comparator, a second high-frequency comparator and a third high-frequency comparator.

[0032] The first high-frequency comparator is configured to compare the amplitude of the high-frequency component detection signal with a first high-frequency threshold voltage and output a comparison result, the second high-frequency comparator is configured to compare the amplitude of the high-frequency component detection signal with a second high-frequency threshold voltage and output a comparison result, and the third high-frequency comparator is configured to compare the amplitude of the high-frequency component detection signal with a third high-frequency threshold voltage and output a comparison result, wherein the first high-frequency threshold voltage, the second high-frequency threshold voltage, and the third high-frequency threshold voltage increase sequentially;

[0033] The output end of the first high-frequency comparator is configured to output the high-frequency enable signal.

[0034] The output end of the second high-frequency comparator and the output end of the third high-frequency comparator are configured to output a two-bit binary high-frequency gain gear signal.

[0035] Further, the high-frequency gain module comprises a high-frequency amplifier and a high-frequency switching switch.

[0036] The negative input end of the high-frequency amplifier is configured to input the to-be-conditioned signal, the output end is connected with the high-frequency filtering module, and the high-frequency enable module is connected between the power supply of the high-frequency amplifier and the power supply port.

[0037] The high-frequency switching switch is feedback connected between the output end and the negative input end of the high-frequency amplifier, and the amplification multiple of the high-frequency amplifier on the to-be-conditioned signal is switched based on the high-frequency gain gear signal.

[0038] Further, the high-frequency switching switch has three analog input ends, two digital input ends, and one analog output end.

[0039] The three analog input ends of the high-frequency switching switch are connected with the negative input end of the high-frequency amplifier through resistors with different resistances, the analog output end of the high-frequency switching switch is connected with the output end of the high-frequency amplifier, and the two digital input ends of the high-frequency switching switch are configured to input the high-frequency gain gear signal.

[0040] The high-frequency switching switch selectively connects one of the three analog input ends and the analog output end thereof based on the high-frequency gain gear signal.

[0041] Preferably, the automatic switching filter and gain dual-frequency CW underwater acoustic signal conditioning circuit further comprises a locking unit, and the locking unit comprises:

[0042] A locking signal module is configured to compare the amplitudes of the low-frequency component detection signal and the high-frequency component detection signal, and generate a low-frequency locking signal and a high-frequency locking signal.

[0043] A low-frequency locking module, which enables or disables the low-frequency gain module based on the low-frequency locking signal and in cooperation with the low-frequency enabling module;

[0044] A high-frequency locking module, which enables or disables the high-frequency gain module based on the high-frequency locking signal and in cooperation with the high-frequency enabling module;

[0045] At any time, the number of modules in the low-frequency enabling module, the high-frequency enabling module, the low-frequency locking module and the high-frequency locking module in the on state does not exceed three.

[0046] When the original underwater acoustic signal is processed using the dual-frequency CW underwater acoustic signal conditioning circuit provided by the present application, the low-frequency conditioning unit and the high-frequency conditioning unit synchronously receive the to-be-conditioned signal output by the preamplification module, and the two conditioning units are activated only when the to-be-conditioned signal contains effective components of the corresponding frequency band, and can adaptively switch the gain position according to the amplitude of the effective components of the corresponding frequency band, so that the appropriate filtering channel and gain multiple can be automatically selected according to the frequency band and amplitude of the original underwater acoustic signal without manual adjustment or digital adjustment through a digital control module. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 The schematic diagram of the architecture of the dual-frequency CW underwater acoustic signal conditioning circuit provided by the present application is shown in the figure.

[0048] Figure 2 The circuit schematic diagram of the preamplification module provided by the present application is shown in the figure.

[0049] Figure 3 The circuit schematic diagram of the low-frequency detection module provided by the present application is shown in the figure.

[0050] Figure 4 The schematic diagram of the architecture of the low-frequency control quantity module provided by the present application is shown in the figure.

[0051] Figure 5 The circuit schematic diagram of the low-frequency control quantity module provided by the present application is shown in the figure.

[0052] Figure 6 The circuit schematic diagram of the low-frequency gain module and the low-frequency enabling module provided by the present application is shown in the figure.

[0053] Figure 7 The circuit schematic diagram of the low-frequency filtering module provided by the present application is shown in the figure.

[0054] Figure 8 The circuit schematic diagram of the high-frequency detection module provided by the present application is shown in the figure.

[0055] Figure 9 This is a schematic diagram of the architecture of the high-frequency control quantity module provided according to an embodiment of this application;

[0056] Figure 10 This is a circuit diagram of the high-frequency gain module and the high-frequency enable module provided according to embodiments of this application;

[0057] Figure 11 This is a circuit diagram of a high-frequency filtering module provided according to an embodiment of this application;

[0058] Figure 12 This is a schematic diagram of the architecture of the locking unit provided according to the embodiments of this application and its cooperation with the low-frequency enable module and the high-frequency enable module;

[0059] Figure 13 This is a schematic diagram of the architecture of the locking signal module provided according to an embodiment of this application;

[0060] Figure 14 This is a circuit diagram of the low-frequency gain module, low-frequency enable module, and low-frequency latch-up module provided according to embodiments of this application.

[0061] Figure 15 A schematic diagram of the amplitude-frequency characteristics of the low-frequency conditioned signal output by the dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain provided in the embodiments of this application;

[0062] Figure 16 This is a schematic diagram of the amplitude-frequency characteristics of the high-frequency conditioned signal output by the dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain provided in the embodiments of this application. Detailed Implementation

[0063] The present application will now be further described based on preferred embodiments and with reference to the accompanying drawings.

[0064] In the description of the embodiments of this application, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product of this application is in use, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, in the description of this application, the terms "first," "second," etc., are used to distinguish different units, but these are not limited by the manufacturing order, nor should they be construed as indicating or implying relative importance. Their names may differ in the detailed description and claims of this application. In addition, for ease of understanding, various components in the drawings have been enlarged or reduced, but this is not intended to limit the scope of protection of this application.

[0065] The vocabulary used in this specification is for illustrative purposes and is not intended to limit the scope of this application. It should also be noted that, unless otherwise expressly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection via an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of these terms in this application.

[0066] Embodiments of this application provide a dual-frequency CW underwater acoustic signal conditioning circuit that automatically switches filtering and gain. Figure 1 A schematic diagram of the architecture of the dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain provided in an embodiment of this application is shown, as follows: Figure 1 As shown, it includes a preamplifier module, a low-frequency conditioning unit, a high-frequency conditioning unit, and an output module.

[0067] Specifically, the preamplifier module is connected to the signal output terminal of the hydrophone to amplify the received raw underwater acoustic signal and output the signal to be conditioned. The low-frequency conditioning unit is connected to the preamplifier module and is enabled when the signal to be conditioned contains effective low-frequency CW components. Based on the amplitude of the effective low-frequency CW components, it performs gain grading and low-frequency filtering on the signal to be conditioned to output a low-frequency conditioned signal. The high-frequency conditioning unit is also connected to the preamplifier module and is enabled when the signal to be conditioned contains effective high-frequency CW components. Based on the amplitude of the effective high-frequency CW components, it performs gain grading and high-frequency filtering on the signal to be conditioned to output a high-frequency conditioned signal. The output module is connected to both the low-frequency conditioning unit and the high-frequency conditioning unit to output either a low-frequency conditioned signal or a high-frequency conditioned signal.

[0068] The dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain provided in this application embodiment can be used to perform graded gain filtering and conditioning on low-frequency and high-frequency dual-band CW signals received by equipment such as three-dimensional imaging sonar. When using this conditioning circuit to process the original underwater acoustic signal, the low-frequency conditioning unit and the high-frequency conditioning unit synchronously receive the signal to be conditioned output by the preamplifier module, automatically determine whether there is a valid low-frequency CW signal or a high-frequency CW signal in the original signal, and conduct the corresponding processing path according to the judgment and adaptively adjust the gain level according to the amplitude of the effective components of the corresponding frequency band. Therefore, without the need for manual adjustment or digital adjustment through a digital control module, it can automatically select the appropriate filtering channel and gain multiple according to the frequency and amplitude of the original underwater acoustic signal.

[0069] The following section, in conjunction with the accompanying drawings, details the optional implementation methods for each functional unit and module.

[0070] Figure 2 Fig. 2 shows a circuit schematic diagram of the pre-amplification module in some optional embodiments, as shown in the figure, the core amplification device of the pre-amplification module is an operational amplifier U0, the power supply end of which is connected with the power supply A3V3_W, the positive input end is connected with the original signal, and the negative input end is connected with the output end through a feedback network, the operational amplifier U0 is used to amplify the original signal input from the hydrophone, and then output the signal as a to-be-conditioned signal to the low-frequency conditioning unit and the high-frequency conditioning unit. Figure 2

[0071] In addition, the pre-amplification module further includes a peripheral circuit composed of a plurality of components, for example, a 1.65V reference power supply is connected to the positive input end of the operational amplifier U0 through a resistor R0_2 to provide a reference voltage; the power supply A3V3_W and the operational amplifier U0 are decoupled through the parallel connection of capacitors C0_1 and C0_2; the feedback network is composed of resistors R0_6 and capacitors C0_5, and input protection is provided through the reverse parallel connection of diodes D0_1 and D0_2.

[0072] As shown in Fig. 3, the low-frequency conditioning unit further includes a low-frequency detection module, a low-frequency control quantity module, a low-frequency enabling module, a low-frequency gain module, and a low-frequency filtering module. Figure 1

[0073] The input end of the low-frequency detection module is connected with the output end of the pre-amplification module, which is used to convert the to-be-conditioned signal output by the pre-amplification module into a direct-current low-frequency component detection signal.

[0074] Figure 3 Fig. 4 shows a circuit schematic diagram of the low-frequency detection module in some optional embodiments, which is used to extract the direct-current amplitude information of the CW signal with a frequency of 300K (in the embodiments of the present application, the CW signal with a frequency of 300K is the low-frequency CW signal) from the to-be-conditioned signal, as shown in the figure. Figure 3 As shown in Fig. 4, the low-frequency detection module mainly includes an active bandpass amplification network composed of two-stage operational amplifiers U1A and U1B, and an output rectification filtering part composed of diodes D1_3 and D1_4, a capacitor C1_11 and a resistor R1_10.

[0075] After the input to-be-conditioned signal is subjected to signal conditioning through the active bandpass amplification network, the signal components other than 300K can be filtered out, then rectified through diodes D1_3 and D1_4, and finally output as a direct-current low-frequency component detection signal through capacitor C1_11 and resistor R1_10, the size of the signal represents the amplitude of the CW signal with a frequency of 300K.

[0076] It should be known that by adjusting the size of the capacitor C1_11 and the resistor R1_10, the amplitude of the CW signal with a frequency of 300K can be adjusted. Figure 3 ​​The parameters of each component in the active band-pass amplification network in the circuit shown can change the frequency passing characteristic of the circuit, thereby realizing the extraction of the high-frequency component detection signal, for example, Figure 8 The circuit schematic of the high-frequency component detection module for extracting the amplitude information of the CW signal with a frequency of 600K is shown in some optional embodiments (in the embodiments of the present application, the CW signal with a frequency of 600K is the high-frequency CW signal), and the comparison Figure 3 、 Figure 8 It can be known that the circuit structures of the two modules are basically the same, and the difference lies in that the parameters of the corresponding components are selected according to the detection requirement of the amplitude of the specific frequency CW signal.

[0077] The input end of the low-frequency control quantity module is connected with the output end of the low-frequency detection module, and the low-frequency control quantity signal is generated according to the amplitude of the low-frequency component detection signal output by the low-frequency detection module, wherein in the embodiments of the present application, the low-frequency control quantity signal output by the low-frequency control quantity module includes two kinds: one is a low-frequency enable signal, which is input into the enable end of the low-frequency enable module to turn on or turn off the low-frequency gain filtering channel, and the other is a low-frequency gain gear signal, which is input into the low-frequency gain module to automatically switch the gain multiple of the low-frequency gain module.

[0078] Figure 4 The circuit schematic of the low-frequency control quantity module in some optional embodiments is shown as follows, Figure 4 As shown in the figure, the low-frequency control quantity module includes a first low-frequency comparator, a second low-frequency comparator and a third low-frequency comparator.

[0079] Among them, the input end of the three low-frequency comparators is connected with the low-frequency detection module to receive the low-frequency component detection signal; the other input end of the first low-frequency comparator inputs the first low-frequency threshold voltage, compares the low-frequency component detection signal and outputs a low-level signal (represented by 0) or a high-level signal (represented by 1) according to the comparison result; the other input end of the second low-frequency comparator inputs the second low-frequency threshold voltage, compares the low-frequency component detection signal and outputs a low-level signal or a high-level signal according to the comparison result; and the other input end of the third low-frequency comparator inputs the third low-frequency threshold voltage, compares the low-frequency component detection signal and outputs a low-level signal or a high-level signal according to the comparison result.

[0080] In the embodiments of the present application, the first low-frequency threshold voltage is less than the second low-frequency threshold voltage, and the second low-frequency threshold voltage is less than the third low-frequency threshold voltage, and by setting the three low-frequency comparators compared with different threshold voltages, four situations of the amplitude of the low-frequency component detection signal can be corresponded.

[0081] Specifically, when the amplitude of the low-frequency component detection signal is lower than the first low-frequency threshold voltage, it indicates that the amplitude of the low-frequency CW component in the signal to be conditioned is too small, and in the embodiments of the present application, this case is referred to as that the signal to be conditioned does not contain an effective low-frequency CW component. Since the active sonar can only emit a low-frequency or high-frequency CW signal at the same time, it can be determined that the active sonar does not emit a signal at this time, or emits a high-frequency CW signal. Accordingly, the gain and filter channel for the low-frequency component need to be turned off to avoid that the last output signal contains a low-frequency component with gain. If the amplitude of the low-frequency component detection signal is higher than the first low-frequency threshold voltage, i.e., the signal to be conditioned contains an effective low-frequency CW component, it can be considered that the active sonar emits a low-frequency CW signal, and the low-frequency gain and filter channel need to be turned on.

[0082] Based on the above analysis, in the embodiments of the present application, the high-low level signal output by the output end of the first low-frequency comparator can be used as a low-frequency enable signal, which is input to the enable end of the low-frequency enable module. The low-frequency enable module turns on or turns off the power supply of the low-frequency gain module according to the high-low level of the signal, so as to enable or disable the low-frequency gain module.

[0083] Further, when the amplitude of the low-frequency component detection signal is higher than the first low-frequency threshold voltage, i.e., in the case that the signal to be conditioned contains an effective low-frequency CW component, there are three amplitude conditions: higher than the first low-frequency threshold voltage and lower than the second low-frequency threshold voltage, higher than the second low-frequency threshold voltage and lower than the third low-frequency threshold voltage, and higher than the third low-frequency threshold voltage. Since the second low-frequency comparator and the third low-frequency comparator can each output a 0 / 1 representing high-low level signal, the 0 / 1 signals output by the output end of the second low-frequency comparator and the output end of the third low-frequency comparator can be used as a binary signal, respectively, so as to output a two-bit binary form of low-frequency gain gear signal.

[0084] Figure 5 The circuit schematic diagram of the low-frequency control module provided according to one specific embodiment is shown in FIG. 2. As shown in FIG. 2, the low-frequency control module comprises a low-frequency gain module, a low-frequency enable module, a first low-frequency comparator, a second low-frequency comparator, and a third low-frequency comparator. Figure 5As shown, in this embodiment, the comparator V3 at the bottom serves as the first low-frequency comparator. Its negative input terminal receives the low-frequency component detection signal. Resistors R2_3 and R2_6, connected between the VCC terminal and the ground terminal, are used for voltage division to generate a first low-frequency threshold voltage, which is then input to the positive input terminal of the comparator. When the amplitude of the low-frequency component detection signal is lower than the first low-frequency threshold voltage, the low-frequency enable signal output by the first low-frequency comparator is a high-level signal. Upon receiving the high-level signal, the enable terminal of the low-frequency enable module disconnects the power supply to the low-frequency amplifier in the low-frequency gain module, thereby disabling the low-frequency gain module. Conversely, when the low-frequency enable signal output by the first low-frequency comparator is a low-level signal, the enable terminal of the low-frequency enable module, upon receiving the low-level signal, turns on the power supply to the low-frequency amplifier in the low-frequency gain module, thereby enabling the low-frequency gain module.

[0085] The comparator V2 in the middle serves as the second low-frequency comparator. Its positive input terminal receives the low-frequency component detection signal, and its negative input terminal receives the second threshold voltage generated by resistors R2_2 and R2_5, and the second threshold voltage is greater than the first threshold voltage. The comparator V1 above serves as the third low-frequency comparator. Its positive input terminal receives the low-frequency component detection signal, and its negative input terminal receives the third threshold voltage generated by resistors R2_1 and R2_4, and the third threshold voltage is greater than the second threshold voltage.

[0086] like Figure 5 As shown, in this embodiment, the output terminal OUT300K0 of the third low-frequency comparator outputs a binary signal of 0 / 1, and the output terminal OUT300K1 of the second low-frequency comparator outputs another binary signal of 0 / 1. Specifically, when the amplitude of the low-frequency component detection signal is higher than the first low-frequency threshold voltage and lower than the second low-frequency threshold voltage, [OUT300K0,OUT300K1]=[0,0]; when the low-frequency component detection signal is higher than the second low-frequency threshold voltage and lower than the third low-frequency threshold voltage, [OUT300K0,OUT300K1]=[0,1]; when the low-frequency component detection signal is higher than the third low-frequency threshold voltage, [OUT300K0,OUT300K1]=[1,1].

[0087] Figure 6 The following diagram illustrates circuit schematics of the low-frequency enable module and the low-frequency gain module in some embodiments, such as... Figure 6As shown, the low-frequency gain module includes a low-frequency amplifier U3A and a low-frequency switching switch S3, and the low-frequency enable module Q1 is a PMOS tube, the enable end (gate) of which receives a low-frequency enable signal, and the source and drain thereof are connected to the power supply (5V) and the power supply port of the low-frequency amplifier U3A, respectively. When the low-frequency enable signal is a low-level signal, the power supply and the power supply port of the low-frequency amplifier U3A are turned on, thereby enabling the low-frequency gain module. When the low-frequency enable signal is a high-level signal, the power supply and the power supply port of the low-frequency amplifier U3A are disconnected, thereby disabling the low-frequency gain module.

[0088] Further, the low-frequency amplifier U3A can be an amplifier of the same or different model as each operational amplifier in Figure 2 , Figure 3 The positive input end thereof is preferably connected to a 1.65V voltage signal to set the DC level of the output signal, and the negative input end is used to input the signal to be conditioned, and a capacitor C3_1 and a resistor R3_2 are connected in series at the negative input end, and the output end thereof is connected to the low-frequency filter module.

[0089] The low-frequency switching switch S3 is feedback connected between the output end and the negative input end of the low-frequency amplifier U3A, and has three analog input ends, two digital input ends, and an analog output end. The three analog input ends are connected to the negative input end of the low-frequency amplifier U3A through resistors with different resistances (i.e. the resistors R3_3, R3_4 and R3_5 from top to bottom in Figure 6 , and the analog output end is connected to the output end of the low-frequency amplifier U3A. In addition, the two digital input ends of the low-frequency switching switch S3 are used to input the low-frequency gain position signal.

[0090] The low-frequency switching switch can be a switch chip with a switchable function (for example, a single-throw three-pole switch chip with a model number of TS5A3357DCUR). The internal logic control module thereof can selectively turn on the connection between one of the three analog input ends and the analog output end according to the 0 / 1 condition of the two-bit binary low-frequency gain position signal. Since the feedback resistors connected to different analog input ends have different resistances, a reverse amplification circuit with different gain multiples can be formed to realize the gain of the signal to be conditioned in different positions.

[0091] Obviously, the resistance values of the resistors R3_3, R3_4 and R3_5 need to match the amplitude of the input low-frequency gain level signal and the low-frequency component detection signal represented thereby, for example, when the amplitude of the low-frequency component detection signal is higher than the first low-frequency threshold voltage and less than the second low-frequency threshold voltage, the low-frequency gain level signal generated by the low-frequency control quantity module is [OUT300K0, OUT300K1] = [0, 0], if the analog input end S1A and the analog output end of the low-frequency switching switch S3 are turned on in this case, the gain multiple is the resistance value of the resistor R3_3 divided by the resistance value of the resistor R3_2; when the amplitude of the low-frequency component detection signal is higher than the second low-frequency threshold voltage and less than the third low-frequency threshold voltage, the low-frequency gain level signal generated by the low-frequency control quantity module is [OUT2, OUT1] = [0, 1], if the analog input end S1B and the analog output end of the low-frequency switching switch S3 are turned on in this case, the gain multiple is the resistance value of the resistor R3_4 divided by the resistance value of the resistor R3_2; when the amplitude of the low-frequency component detection signal is higher than the third low-frequency threshold voltage, the low-frequency gain level signal generated by the low-frequency control quantity module is [OUT2, OUT1] = [1, 1], if the analog input end S1C and the analog output end of the low-frequency switching switch S3 are turned on in this case, the gain multiple is the resistance value of the resistor R3_5 divided by the resistance value of the resistor R3_2. Obviously, in this connection mode, the resistance value of the resistor R3_3 should be greater than the resistance value of the resistor R3_4, and the resistance value of the resistor R3_4 should be greater than the resistance value of the resistor R3_5, so as to perform gain with a larger multiple on the low-frequency component with a smaller amplitude.

[0092] The input end of the low-frequency filter module is connected with the output end of the low-frequency gain module, for performing low-frequency filtering on the low-frequency gain signal output by the low-frequency gain module, to generate and output a low-frequency conditioning signal. Figure 7 The circuit schematic diagram of the low-frequency filter module in some optional embodiments is shown. Figure 7 As shown, the low-frequency filter module is composed of two-stage filter networks of the cascaded operational amplifiers U4A and U4B and their peripheral circuits, and the low-frequency conditioning signal with a final output frequency of 300 KHz is output after filtering the low-frequency gain signal.

[0093] The architecture of the high-frequency conditioning unit is similar to that of the low-frequency conditioning unit, as shown. Figure 1 As shown, it further includes a high-frequency detection module, a high-frequency control quantity module, a high-frequency enabling module, a high-frequency gain module and a high-frequency filter module.

[0094] Specifically, the high-frequency detection module is configured to convert the to-be-conditioned signal into a direct-current high-frequency component detection signal; the high-frequency control quantity module is configured to generate a high-frequency control quantity signal based on an amplitude of the high-frequency component detection signal, wherein the high-frequency control quantity signal comprises a high-frequency enable signal and a high-frequency gain level signal; the high-frequency enable module is configured to enable or disable the high-frequency gain module based on the high-frequency enable signal; the high-frequency gain module is configured to perform high-frequency gain grading on the to-be-conditioned signal based on the high-frequency gain level signal in an enabled state; and the high-frequency filtering module is configured to perform high-frequency filtering on a signal output by the high-frequency gain module and output a high-frequency conditioned signal.

[0095] Further, the high-frequency control quantity module comprises a first high-frequency comparator, a second high-frequency comparator and a third high-frequency comparator; the first high-frequency comparator is configured to compare the amplitude of the high-frequency component detection signal with a first high-frequency threshold voltage and output a comparison result, the second high-frequency comparator is configured to compare the amplitude of the high-frequency component detection signal with a second high-frequency threshold voltage and output a comparison result, and the third high-frequency comparator is configured to compare the amplitude of the high-frequency component detection signal with a third high-frequency threshold voltage and output a comparison result; the first high-frequency threshold voltage, the second high-frequency threshold voltage and the third high-frequency threshold voltage increase in turn; the output end of the first high-frequency comparator is configured to output the high-frequency enable signal; and the output end of the second high-frequency comparator and the output end of the third high-frequency comparator are configured to output a two-bit binary high-frequency gain level signal.

[0096] Further, the high-frequency gain module comprises a high-frequency amplifier and a high-frequency switching switch; the negative input end of the high-frequency amplifier is configured to input the to-be-conditioned signal, the output end of the high-frequency amplifier is connected with the high-frequency filtering module, and the high-frequency enable module is connected between the power supply of the high-frequency amplifier and the power supply port; the high-frequency switching switch is feedback connected between the output end and the negative input end of the high-frequency amplifier, and is configured to switch the amplification multiple of the high-frequency amplifier on the to-be-conditioned signal based on the high-frequency gain level signal.

[0097] Further, the high-frequency switching switch has three analog input ends, two digital input ends and one analog output end; the three analog input ends of the high-frequency switching switch are connected with the negative input end of the high-frequency amplifier through resistors with different resistances, the analog output end of the high-frequency switching switch is connected with the output end of the high-frequency amplifier, and the two digital input ends of the high-frequency switching switch are configured to input the high-frequency gain level signal; the high-frequency switching switch is configured to selectively conduct the connection between one of the three analog input ends and the analog output end thereof based on the high-frequency gain level signal.

[0098] Figure 8 FIG. 1 is a circuit schematic diagram of a high-frequency detection module according to some embodiments of the present application; Figure 9 FIG. 2 is an architectural schematic diagram of a high-frequency control quantity module provided according to some embodiments of the present application; Figure 10A circuit schematic diagram of a high-frequency gain module and a high-frequency enable module according to some embodiments of the present application is provided. Figure 11 A circuit schematic diagram of a high-frequency filter module according to some embodiments of the present application is provided. The specific implementation of each module of the high-frequency conditioning unit can refer to the description of the low-frequency conditioning unit, which will not be repeated here.

[0099] Since the three-dimensional imaging sonar works in a complex marine environment, there are noises in each frequency band. When the noise components contain the high-frequency or low-frequency components of the three-dimensional imaging sonar, and the amplitude exceeds the first low-frequency threshold voltage or the first high-frequency threshold voltage, it will be mistaken for an effective low-frequency CW signal or an effective high-frequency CW signal, so that the two gain filter channels are activated at the same time. And since the noise level is low at this time, it may be amplified with a higher gain, resulting in false gain of noise components.

[0100] Therefore, in some preferred embodiments, the conditioning circuit is also provided with a locking unit for preventing the low-frequency conditioning unit or the high-frequency conditioning unit from being mistakenly turned on.

[0101] Figure 12 The architecture of the locking unit and its cooperation with the low-frequency enable module and the high-frequency enable module in some preferred embodiments are shown as follows: Figure 12 As shown, the locking unit includes a locking signal module, a low-frequency locking module, and a high-frequency locking module. The locking signal module has two input ends inputting a low-frequency component detection signal and a high-frequency component detection signal, respectively. After comparing the amplitudes of the two signals, a low-frequency locking signal and a high-frequency locking signal are generated and outputted. The low-frequency locking module cooperates with the low-frequency enable module based on the low-frequency locking signal it receives to enable or disable the low-frequency gain module. The high-frequency locking module cooperates with the high-frequency enable module based on the high-frequency locking signal it receives to enable or disable the high-frequency gain module.

[0102] Figure 13 The architecture of the locking signal module in one specific embodiment is shown as follows. In this embodiment, the locking signal module is composed of a high-low frequency component comparator and an inverter. The high-low frequency component comparator can be various suitable comparator chips known to those skilled in the art, such as the same type of comparator as in the low-frequency control quantity module or the high-frequency control quantity module. The two input ends of the high-low frequency component comparator input a low-frequency component detection signal and a high-frequency component detection signal, respectively (for example, the positive input end inputs the low-frequency component detection signal, and the negative input end inputs the high-frequency component detection signal). The output end is divided into two lines, and one of the lines is connected to the inverter (for example, the line corresponding to the low-frequency locking signal is inverted).

[0103] Thus, no matter whether the comparison result of the low-frequency component detection signal and the high-frequency component detection signal is high level or low level, the levels of the low-frequency lock signal and the high-frequency lock signal remain mutually exclusive, for example, when the low-frequency component detection signal is greater than the high-frequency component detection signal, the low-frequency lock signal is low level and the high-frequency lock signal is high level, and correspondingly, appropriate MOS tubes or other devices capable of switching on and off can be selected to construct the low-frequency lock module and the high-frequency lock module (for example, low-level conducting PMOS tubes are selected as the low-frequency lock module and the high-frequency lock module).

[0104] Figure 14 The circuit schematic diagrams of the low-frequency gain module, the low-frequency enable module and the low-frequency lock module in some specific implementations are shown as follows: Figure 14 As shown, the low-frequency lock module Q3 selects the same PMOS tube as the low-frequency enable module Q1, and the two are connected in series between the power supply and the supply port of the low-frequency amplifier U3A, and through mutual cooperation between each other, the low-frequency gain module is enabled or disabled. Obviously, the high-frequency lock module can be added in the circuit containing the high-frequency gain module and the high-frequency enable module. Figure 14

[0105] The working principle of the lock unit will be described below in combination with Figure 12 to Figure 14

[0106] 1) When the amplitude of the low-frequency component detection signal is lower than the first low-frequency threshold voltage and the amplitude of the high-frequency component detection signal is lower than the first high-frequency threshold voltage, it indicates that the active sonar does not emit active signals, and since the low-frequency enable module and the high-frequency enable module are both turned off at this time, no matter what level the lock signal received by the two lock modules is, the two gain filter channels are closed.

[0107] 2) When the amplitude of the low-frequency component detection signal is higher than the first low-frequency threshold voltage and the amplitude of the high-frequency component detection signal is lower than the first high-frequency threshold voltage, it indicates that the active sonar emits low-frequency CW signals and the echo has been identified as containing effective low-frequency CW components, and the detection result of the high-frequency component indicates that it does not contain effective high-frequency CW components, at this time, the low-frequency enable module is turned on and the high-frequency enable module is turned off, and at the same time, since the amplitude of the low-frequency component detection signal is also higher than the amplitude of the high-frequency component detection signal at this time, the lock signal module outputs low-level low-frequency lock signal and high-level high-frequency lock signal, therefore, the low-frequency lock module is also turned on, at this time, only low-frequency gain filtering can be performed, and the high-frequency lock module is in the same off state as the high-frequency enable module.

[0108] ​​3) When the amplitude of the low-frequency component detection signal is lower than the first low-frequency threshold voltage and the amplitude of the high-frequency component detection signal is higher than the first high-frequency threshold voltage, referring to the analysis of the second case, it can be seen that the low-frequency enable module and the low-frequency latch-up module are both disconnected, while the high-frequency enable module and the high-frequency latch-up module are both turned on. Therefore, only high-frequency gain filtering can be performed at this time.

[0109] 4) When the amplitude of the low-frequency component detection signal is higher than the first low-frequency threshold voltage and the amplitude of the high-frequency component detection signal is higher than the first high-frequency threshold voltage, both the low-frequency enable module and the high-frequency enable module are turned on. That is, one of the gain filtering channels mistakenly identifies noise as a valid CW signal. At this time, the latching signal module compares the amplitudes of the low-frequency component detection signal and the high-frequency component detection signal, and identifies the signal with the higher amplitude as the echo signal emitted by the active sonar. For example, when the amplitude of the low-frequency component detection signal is higher than the amplitude of the high-frequency component detection signal, the low-frequency latching signal is low and the high-frequency latching signal is high, thereby turning on the low-frequency latching module and turning off the high-frequency latching module to ensure that only low-frequency gain filtering is performed. Conversely, when the amplitude of the low-frequency component detection signal is lower than the amplitude of the high-frequency component detection signal, the low-frequency latching signal is high and the high-frequency latching signal is low, thereby turning on the high-frequency latching module and turning off the low-frequency latching module to ensure that only high-frequency gain filtering is performed.

[0110] The above analysis shows that at any given time, no more than three of the following modules—the low-frequency enable module, the high-frequency enable module, the low-frequency latch-up module, and the high-frequency latch-up module—are in the on state. Through the cooperation of the latch-up unit and the low-frequency and high-frequency enable modules, it is possible to ensure the processing of effective low-frequency or high-frequency CW signals emitted by the active sound source and received by the hydrophone, while avoiding incorrect amplification of noise that is mistakenly identified as a valid signal.

[0111] It should be known that, Figure 13 , Figure 14 The embodiment shown is only one optional implementation of the latching unit. Without departing from its working principle, the two latching signals output by the latching signal unit and the two latching modules can be flexibly combined. For example, without setting an inverter (i.e., the two latching signals are in phase), a high-level conducting NMOS transistor and a low-level conducting PMOS transistor can be selected as the low-frequency latching module and the high-frequency latching module, respectively. This can also achieve the effect that at any given time, the number of modules in the low-frequency enable module, high-frequency enable module, low-frequency latching module, and high-frequency latching module that are in the conducting state does not exceed three.

[0112] In order to verify the performance of the conditioning circuit provided in the application, a function generator XFG1 is used to generate a sweep signal with an amplitude of 100 mV and a frequency of 0-650 kHz, and a Bode analyzer XBP9 is connected to the input and output ports respectively, Figure 15 、 Figure 16 The amplitude-frequency characteristics of the low-frequency conditioning signal output by the low-frequency conditioning unit and the high-frequency conditioning signal output by the high-frequency conditioning unit are shown respectively, and it can be seen from Figure 15 、 Figure 16 that the signal gain almost reaches 41 dB at the frequencies of 298 kHz and 601 kHz.

[0113] The specific embodiments of the application are described in detail above, and for those skilled in the art, without departing from the principles of the application, some improvements and modifications can be made to the application, and these improvements and modifications also belong to the protection scope of the claims of the application.

Claims

1. A dual frequency CW underwater acoustic signal conditioning circuit with automatic switching of filter and gain, characterized by, The method comprises the following steps: A pre-amplification module amplifies the received original underwater acoustic signal and outputs a signal to be conditioned; A low-frequency conditioning unit is enabled when the signal to be conditioned contains an effective low-frequency CW component, and performs gain grading and low-frequency filtering on the signal to be conditioned based on the amplitude of the effective low-frequency CW component to output a low-frequency conditioned signal; A high-frequency conditioning unit is enabled when the signal to be conditioned contains an effective high-frequency CW component, and performs gain grading and high-frequency filtering on the signal to be conditioned based on the amplitude of the effective high-frequency CW component to output a high-frequency conditioned signal; An output module outputs the low-frequency conditioned signal or the high-frequency conditioned signal; The low-frequency conditioning unit comprises a low-frequency detection module, a low-frequency control quantity module, a low-frequency enabling module, a low-frequency gain module, and a low-frequency filtering module; The low-frequency detection module converts the signal to be conditioned into a direct-current low-frequency component detection signal; The low-frequency control quantity module generates a low-frequency control quantity signal based on the amplitude of the low-frequency component detection signal, wherein the low-frequency control quantity signal comprises a low-frequency enabling signal and a low-frequency gain level signal; The low-frequency enabling module enables or disables the low-frequency gain module based on the low-frequency enabling signal; The low-frequency gain module performs gain grading on the signal to be conditioned based on the low-frequency gain level signal in the enabled state; The low-frequency filtering module performs low-frequency filtering on the signal output by the low-frequency gain module and outputs the low-frequency conditioned signal; The low-frequency control quantity module comprises a first low-frequency comparator, a second low-frequency comparator, and a third low-frequency comparator; The first low-frequency comparator compares the amplitude of the low-frequency component detection signal with a first low-frequency threshold voltage and outputs a comparison result, the second low-frequency comparator compares the amplitude of the low-frequency component detection signal with a second low-frequency threshold voltage and outputs a comparison result, and the third low-frequency comparator compares the amplitude of the low-frequency component detection signal with a third low-frequency threshold voltage and outputs a comparison result, wherein the first low-frequency threshold voltage, the second low-frequency threshold voltage, and the third low-frequency threshold voltage increase in order; The output end of the first low-frequency comparator outputs the low-frequency enabling signal; The output end of the second low-frequency comparator and the output end of the third low-frequency comparator output a two-bit binary low-frequency gain level signal; The low-frequency gain module comprises a low-frequency amplifier and a low-frequency switching switch; The negative input end of the low-frequency amplifier inputs the signal to be conditioned, the output end is connected with the low-frequency filtering module, and the low-frequency enabling module is connected between the power supply of the low-frequency amplifier and the power supply port; The low-frequency switching switch is feedback connected between the output end and the negative input end of the low-frequency amplifier, and switches the amplification multiple of the low-frequency amplifier on the signal to be conditioned based on the low-frequency gain level signal; The low-frequency switching switch has three analog input ends, two digital input ends, and one analog output end; The three analog inputs of the low-frequency switching switch are connected to the negative input of the low-frequency amplifier through resistors with different resistance values, the analog output of the low-frequency switching switch is connected to the output of the low-frequency amplifier, and the two digital inputs of the low-frequency switching switch are used to input the low-frequency gain level signal; The low-frequency switching switch selectively turns on the connection between one of the three analog inputs and the analog output based on the low-frequency gain level signal.

2. The dual-frequency CW underwater acoustic signal conditioning circuit of claim 1, wherein the high-frequency conditioning unit comprises a high-frequency detection module, a high-frequency control quantity module, a high-frequency enabling module, a high-frequency gain module, and a high-frequency filtering module. The high-frequency detection module is configured to convert the to-be-conditioned signal into a direct-current high-frequency component detection signal. The high-frequency control quantity module is configured to generate a high-frequency control quantity signal based on the amplitude of the high-frequency component detection signal, wherein the high-frequency control quantity signal comprises a high-frequency enabling signal and a high-frequency gain level signal. The high-frequency enabling module is configured to enable or disable the high-frequency gain module based on the high-frequency enabling signal. The high-frequency gain module is configured to perform gain grading on the to-be-conditioned signal based on the high-frequency gain level signal in an enabled state. The high-frequency filtering module is configured to perform high-frequency filtering on the signal output by the high-frequency gain module and output the high-frequency conditioning signal.

3. The dual-frequency CW underwater acoustic signal conditioning circuit of claim 2, wherein the high-frequency control quantity module comprises a first high-frequency comparator, a second high-frequency comparator, and a third high-frequency comparator. The first high-frequency comparator is configured to compare the amplitude of the high-frequency component detection signal with a first high-frequency threshold voltage and output a comparison result, the second high-frequency comparator is configured to compare the amplitude of the high-frequency component detection signal with a second high-frequency threshold voltage and output a comparison result, and the third high-frequency comparator is configured to compare the amplitude of the high-frequency component detection signal with a third high-frequency threshold voltage and output a comparison result, wherein the first high-frequency threshold voltage, the second high-frequency threshold voltage, and the third high-frequency threshold voltage increase in order. The output of the first high-frequency comparator is configured to output the high-frequency enabling signal. The output of the second high-frequency comparator and the output of the third high-frequency comparator are configured to output a two-bit binary high-frequency gain level signal.

4. The dual-frequency CW underwater acoustic signal conditioning circuit of claim 3, wherein the high-frequency gain module comprises a high-frequency amplifier and a high-frequency switching switch. The negative input of the high-frequency amplifier is configured to input the to-be-conditioned signal, the output is connected to the high-frequency filtering module, and the high-frequency enabling module is connected between the power supply of the high-frequency amplifier and the power supply port. The high-frequency switching switch is feedback connected between the output and the negative input of the high-frequency amplifier, and switches the amplification multiple of the high-frequency amplifier on the to-be-conditioned signal based on the high-frequency gain level signal. ​ ​ ​ 5. The dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching of filter and gain according to claim 4, characterized in that, the high-frequency switching switch has three analog input terminals, two digital input terminals, and one analog output terminal; the three analog input terminals of the high-frequency switching switch are connected to the negative input terminal of the high-frequency amplifier through resistors with different resistance values, the analog output terminal of the high-frequency switching switch is connected to the output terminal of the high-frequency amplifier, and the two digital input terminals of the high-frequency switching switch are used to input the high-frequency gain level signal; the high-frequency switching switch selectively connects one of its three analog input terminals to its analog output terminal based on the high-frequency gain level signal.

6. The dual frequency CW underwater acoustic signal conditioning circuit with automatic switching of filter and gain according to claim 2, characterized in that, Further comprising a locking unit, the locking unit comprising: a locking signal module for comparing the amplitudes of the low-frequency component detection signal and the high-frequency component detection signal and generating a low-frequency locking signal and a high-frequency locking signal; a low-frequency locking module for enabling or disabling the low-frequency gain module based on the low-frequency locking signal and in cooperation with the low-frequency enabling module; a high-frequency locking module for enabling or disabling the high-frequency gain module based on the high-frequency locking signal and in cooperation with the high-frequency enabling module; wherein at any time, the number of modules in the on state among the low-frequency enabling module, the high-frequency enabling module, the low-frequency locking module, and the high-frequency locking module does not exceed three.

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