Dual-frequency CW underwater acoustic signal conditioning circuit capable of automatically switching filtering and gain

Abstract

The invention belongs to the technical field of underwater acoustic signal processing, and provides a dual-frequency CW underwater acoustic signal conditioning circuit capable of automatically switching filtering and gain, which comprises a pre-amplification module for amplifying a received original underwater acoustic signal and outputting a to-be-conditioned signal; the low-frequency conditioning unit is enabled when the to-be-conditioned signal contains an effective low-frequency CW component and performs gear gain and filtering on the to-be-conditioned signal to output a low-frequency conditioning signal; the high-frequency conditioning unit is used for performing gear gain and high-frequency filtering on the to-be-conditioned signal when the to-be-conditioned signal contains an effective high-frequency CW component so as to output a high-frequency conditioned signal; and the output module is used for outputting the low-frequency conditioning signal or the high-frequency conditioning signal. According to the technical scheme of the invention, the appropriate filtering channel and gain multiple can be automatically selected according to the frequency and amplitude of the original underwater acoustic signal.

Description

Technical Field

[0001] This application belongs to the field of underwater acoustic signal processing technology, specifically, it provides a dual-frequency CW underwater acoustic signal conditioning circuit that automatically switches filtering and gain. Background Technology

[0002] In the field of underwater acoustic detection, depending on the application scenario and task, it is often necessary to receive and process CW (Continuous Wave) underwater acoustic signals of specific frequencies. For example, when using 3D imaging sonar to detect underwater objects or terrain, a 300K frequency CW signal can be used for long-distance detection to perform large-scale search and positioning; a 600K frequency CW signal can be used for close-range fine imaging to capture target details and precise shapes. In the above application scenarios, the 300K CW signal can be called a low-frequency CW signal, and the 600K CW signal can be called a high-frequency CW signal. Accordingly, in the signal reception and processing stage, it is necessary to ensure that the signal conditioning circuit has good processing capabilities for both low-frequency and high-frequency CW underwater acoustic signals.

[0003] Currently, common underwater acoustic conditioning circuits for processing low-frequency and high-frequency CW underwater acoustic signals mainly include the following solutions: Manually selecting low-frequency and high-frequency gain filter circuits and adjusting the gain factor based on the frequency of the actively transmitted signal and the amplitude of the received signal. This method has low gain adjustment accuracy and poor flexibility, and cannot effectively judge and automatically switch filter circuits. Using broadband filters for signal filtering allows signals within a wide frequency range to pass through; however, it cannot adaptively compensate for the attenuation of characteristic frequency signals. Using digital control modules such as CPUs to achieve circuit gain control and filter circuit switching in the relevant adjustment parts through digital signal processing; however, this method requires additional computing resources and has high implementation costs. Summary of the Invention

[0004] To address the problems existing in the prior art, this application provides a dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching of filtering and gain, comprising: The preamplifier module amplifies the received raw underwater acoustic signal and outputs the signal to be conditioned. The low-frequency conditioning unit is enabled when the signal to be conditioned contains an effective low-frequency CW component, and performs step-by-step gain 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 conditioning signal. The high-frequency conditioning unit is enabled when the signal to be conditioned contains an effective high-frequency CW component, and performs level-by-level gain 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. The output module is used to output the low-frequency conditioning signal or the high-frequency conditioning signal.

[0005] Furthermore, the low-frequency conditioning unit includes a low-frequency detection module, a low-frequency control module, a low-frequency enable module, a low-frequency gain module, and a low-frequency filtering module; The low-frequency detection module is used to convert the signal to be conditioned into a DC 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 includes a low-frequency enable signal and a low-frequency gain level signal. The low-frequency enable module enables or disables the low-frequency gain module based on the low-frequency enable signal; When enabled, the low-frequency gain module performs gain tiers on the signal to be conditioned based on the low-frequency gain level signal. The low-frequency filtering module is used to perform low-frequency filtering on the signal output by the low-frequency gain module and output the low-frequency conditioning signal.

[0006] Furthermore, the high-frequency conditioning unit includes a high-frequency detection module, a high-frequency control module, a high-frequency enable module, a high-frequency gain module, and a high-frequency filtering module; The high-frequency detection module is used to convert the signal to be conditioned into a DC high-frequency component detection signal; The high-frequency control quantity module generates a high-frequency control quantity signal based on the amplitude of the high-frequency component detection signal, wherein the high-frequency control quantity signal includes a high-frequency enable signal and a high-frequency gain level signal. The high-frequency enable module enables or disables the high-frequency gain module based on the high-frequency enable signal; When enabled, the high-frequency gain module performs level-based gain on the signal to be conditioned based on the high-frequency gain level signal. The high-frequency filtering module is used to perform high-frequency filtering on the signal output by the high-frequency gain module and output the high-frequency conditioning signal.

[0007] Furthermore, the low-frequency control module includes a first low-frequency comparator, a second low-frequency comparator, and a third low-frequency comparator; The first low-frequency comparator is used to compare the amplitude of the low-frequency component detection signal with the first low-frequency threshold voltage and output the comparison result; the second low-frequency comparator is used to compare the amplitude of the low-frequency component detection signal with the second low-frequency threshold voltage and output the comparison result; the third low-frequency comparator is used to compare the amplitude of the low-frequency component detection signal with the third low-frequency threshold voltage and output the comparison result; the first low-frequency threshold voltage, the second low-frequency threshold voltage, and the third low-frequency threshold voltage increase sequentially. The output of the first low-frequency comparator is used to output the low-frequency enable signal; The output terminals of the second low-frequency comparator and the third low-frequency comparator are used to output a two-bit binary low-frequency gain level signal.

[0008] Furthermore, the low-frequency gain module includes a low-frequency amplifier and a low-frequency switching switch; The negative input terminal of the low-frequency amplifier is used to input the signal to be conditioned, and the output terminal is connected to the low-frequency filter module. The low-frequency enable module is connected between the power supply and the power supply port of the low-frequency amplifier. The low-frequency switching switch is connected between the output terminal and the negative input terminal of the low-frequency amplifier, and switches the amplification factor of the low-frequency amplifier for the signal to be conditioned based on the low-frequency gain level signal.

[0009] Furthermore, the low-frequency switching switch has three analog input terminals, two digital input terminals, and one analog output terminal; The three analog input terminals of the low-frequency switch are connected to the negative input terminal of the low-frequency amplifier through resistors with different resistance values. The analog output terminal of the low-frequency switch is connected to the output terminal of the low-frequency amplifier. The two digital input terminals of the low-frequency switch are used to input the low-frequency gain level signal. The low-frequency switching switch selectively connects one of its three analog input terminals to its analog output terminal based on the low-frequency gain level signal.

[0010] Furthermore, the high-frequency control module includes a first high-frequency comparator, a second high-frequency comparator, and a third high-frequency comparator; The first high-frequency comparator is used to compare the amplitude of the high-frequency component detection signal with the first high-frequency threshold voltage and output the comparison result. The second high-frequency comparator is used to compare the amplitude of the high-frequency component detection signal with the second high-frequency threshold voltage and output the comparison result. The third high-frequency comparator is used to compare the amplitude of the high-frequency component detection signal with the third high-frequency threshold voltage and output the comparison result. The first high-frequency threshold voltage, the second high-frequency threshold voltage, and the third high-frequency threshold voltage increase sequentially. The output of the first high-frequency comparator is used to output the high-frequency enable signal; The output terminals of the second and third high-frequency comparators are used to output two-bit binary high-frequency gain level signals.

[0011] Furthermore, the high-frequency gain module includes a high-frequency amplifier and a high-frequency switching switch; The negative input terminal of the high-frequency amplifier is used to input the signal to be conditioned, and the output terminal is connected to the high-frequency filtering module. The high-frequency enable module is connected between the power supply and the power supply port of the high-frequency amplifier. The high-frequency switching switch is connected between the output terminal and the negative input terminal of the high-frequency amplifier, and switches the amplification factor of the high-frequency amplifier for the signal to be conditioned based on the high-frequency gain level signal.

[0012] Furthermore, 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 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 switch is connected to the output terminal of the high-frequency amplifier. The two digital input terminals of the high-frequency 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.

[0013] Preferably, the dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain further includes a lock-up unit, the lock-up unit comprising: A lock-up signal module is used to compare the amplitudes of the low-frequency component detection signal and the high-frequency component detection signal, and to generate a low-frequency lock-up signal and a high-frequency lock-up signal. A low-frequency lock-up module, based on the low-frequency lock-up signal and in cooperation with the low-frequency enable module, enables or disables the low-frequency gain module. A high-frequency latching module, based on the high-frequency latching signal and in conjunction with the high-frequency enable module, enables or disables the high-frequency gain module; 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 on state does not exceed three.

[0014] When processing the original underwater acoustic signal using the dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain provided in this application, the low-frequency conditioning unit and the high-frequency conditioning unit synchronously receive the signal to be conditioned from the preamplifier module. The two conditioning units are activated only when the signal to be conditioned contains effective components of the corresponding frequency band, and can adaptively switch 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, the appropriate filtering channel and gain factor can be automatically selected according to the frequency band and amplitude of the original underwater acoustic signal. Attached Figure Description

[0015] Figure 1This is a schematic diagram of the architecture of a dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain provided in an embodiment of this application; Figure 2 This is a circuit schematic diagram of a preamplifier module provided according to an embodiment of this application; Figure 3 This is a circuit diagram of a low-frequency detection module provided according to an embodiment of this application; Figure 4 This is a schematic diagram of the architecture of a low-frequency control module provided according to an embodiment of this application; Figure 5 This is a circuit diagram of a low-frequency control module provided according to an embodiment of this application; Figure 6 This is a circuit diagram of a low-frequency gain module and a low-frequency enable module provided according to embodiments of this application; Figure 7 This is a circuit diagram of a low-frequency filtering module provided according to an embodiment of this application; Figure 8 This is a circuit diagram of a high-frequency detection module provided according to an embodiment of this application; 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; Figure 10 This is a circuit diagram of the high-frequency gain module and high-frequency enable module provided according to embodiments of this application; Figure 11 This is a circuit diagram of a high-frequency filtering module provided according to an embodiment of this application; 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; Figure 13 This is a schematic diagram of the architecture of the locking signal module provided according to an embodiment of this application; 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. 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; 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

[0016] The present application will now be further described based on preferred embodiments and with reference to the accompanying drawings.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The following section, in conjunction with the accompanying drawings, details the optional implementation methods for each functional unit and module.

[0023] Figure 2 The diagram shows a circuit schematic of the preamplifier module in some optional embodiments, such as... Figure 2 As shown, the core amplification device of the preamplifier module is operational amplifier U0, whose power supply terminal is connected to power supply A3V3_W, the positive input terminal is connected to the original signal, and the negative input terminal is connected to the output terminal via a feedback network. Operational amplifier U0 is used to amplify the original signal input from the hydrophone and then output it as the signal to be conditioned to the low-frequency conditioning unit and the high-frequency conditioning unit.

[0024] In addition, the preamplifier module also includes peripheral circuits composed of several components. For example, a 1.65V reference power supply is connected to the positive input terminal of the operational amplifier U0 through a resistor R0_2 to provide a reference voltage; the power supply A3V3_W is decoupled from the operational amplifier U0 through capacitors C0_1 and C0_2 connected in parallel; the feedback network is composed of a resistor R0_6 and a capacitor C0_5, and provides input protection through diodes D0_1 and D0_2 connected in reverse parallel.

[0025] like Figure 1 As shown, the low-frequency conditioning unit further includes a low-frequency detection module, a low-frequency control module, a low-frequency enable module, a low-frequency gain module, and a low-frequency filter module.

[0026] The input of the low-frequency detection module is connected to the output of the preamplifier module, and is used to convert the signal to be conditioned from the preamplifier module into a DC low-frequency component detection signal.

[0027] Figure 3The diagram illustrates a circuit diagram of a low-frequency detection module in some optional embodiments. This module is used to extract the DC amplitude information of a 300kHz CW signal from the signal to be conditioned (in the embodiments of this application, the 300kHz CW signal is considered a low-frequency CW signal). Figure 3 As shown, the low-frequency detection module mainly includes an active bandpass amplifier network composed of two operational amplifiers U1A and U1B, and an output rectification and filtering section composed of diodes D1_3 and D1_4, capacitor C1_11 and resistor R1_10.

[0028] The input signal to be conditioned is conditioned by an active bandpass amplifier network, which can filter out signal components other than 300K. Then it is rectified by diodes D1_3 and D1_4, and finally outputs a low-frequency component detection signal in DC form through capacitor C1_11 and resistor R1_10. The magnitude of this signal represents the amplitude of the 300K CW signal.

[0029] It should be known that, through adjustment Figure 3 The parameters of the components in the active bandpass amplifier network shown in the circuit can be adjusted to change the frequency pass characteristics of the circuit, thereby enabling the extraction of high-frequency components from the detection signal. For example... Figure 8 The diagram illustrates a circuit diagram of a high-frequency component detection module for extracting amplitude information of a 600kHz CW signal in some optional embodiments (in the embodiments of this application, a 600kHz CW signal is used as a high-frequency CW signal). Figure 3 , Figure 8 As can be seen, the circuit structures of the two modules are basically the same. The difference lies in the need to select the appropriate component parameters for the detection requirements of CW signal amplitude at a specific frequency.

[0030] The input terminal of the low-frequency control module is connected to the output terminal of the low-frequency detection module. The low-frequency control signal is generated based on the amplitude of the low-frequency component detection signal output by the low-frequency detection module. In the embodiments of this application, the low-frequency control signal output by the low-frequency control module includes two types: one is a low-frequency enable signal, which is input to the enable terminal of the low-frequency enable module to turn on or off the low-frequency gain filter channel; the other is a low-frequency gain level signal, which is input to the low-frequency gain module to automatically switch the gain factor of the low-frequency gain module.

[0031] Figure 4 The diagram shows a circuit schematic of the low-frequency control module in some optional embodiments, such as... Figure 4 As shown, the low-frequency control module includes a first low-frequency comparator, a second low-frequency comparator, and a third low-frequency comparator.

[0032] Each of the three low-frequency comparators has one input terminal connected to the low-frequency detection module to receive the low-frequency component detection signal. The other input terminal of the first low-frequency comparator receives a first low-frequency threshold voltage, which is compared with the low-frequency component detection signal, and outputs a low-level signal (represented by 0) or a high-level signal (represented by 1) based on the comparison result. The other input terminal of the second low-frequency comparator receives a second low-frequency threshold voltage, which is compared with the low-frequency component detection signal, and outputs a low-level signal or a high-level signal based on the comparison result. The other input terminal of the third low-frequency comparator receives a third low-frequency threshold voltage, which is compared with the low-frequency component detection signal, and outputs a low-level signal or a high-level signal based on the comparison result.

[0033] In the embodiments of this 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. By setting three low-frequency comparators that are compared with different threshold voltages, four cases of low-frequency component detection signal amplitude can be addressed.

[0034] 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. In the embodiments of this application, this situation is referred to as the signal to be conditioned not containing effective low-frequency CW components. Since the active sonar can only selectively transmit low-frequency or high-frequency CW signals at the same time, it can be determined that the active sonar is not transmitting a signal at this time, or is transmitting a high-frequency CW signal. Accordingly, the gain and filtering channels for the low-frequency components need to be turned off to avoid the final output signal containing the amplified low-frequency components. If the amplitude of the low-frequency component detection signal is higher than the first low-frequency threshold voltage, that is, the signal to be conditioned contains effective low-frequency CW components, it can be considered that the active sonar is transmitting a low-frequency CW signal, and the low-frequency gain and filtering channels need to be turned on.

[0035] Based on the above analysis, in the embodiments of this application, the high and low level signals output by the output terminal of the first low-frequency comparator can be used as low-frequency enable signals. The low-frequency enable signal is input to the enable terminal of the low-frequency enable module, and the low-frequency enable module turns on or off the power supply of the low-frequency gain module according to the high or low level of the signal, thereby enabling or disabling the low-frequency gain module.

[0036] Furthermore, when the amplitude of the low-frequency component detection signal is higher than the first low-frequency threshold voltage, i.e., when the signal to be conditioned contains effective low-frequency CW components, there are three amplitude cases: 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 and third low-frequency comparators can each output a high / low level signal represented by 0 / 1, the 0 / 1 signals output by the output terminals of the second and third low-frequency comparators can each be used as a single bit of binary signal, thereby outputting a two-bit binary low-frequency gain level signal.

[0037] Figure 5 A circuit diagram of a low-frequency control module according to a specific embodiment is shown, such as... Figure 5 As 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.

[0038] 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.

[0039] like Figure 5As 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].

[0040] 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 6 As shown, the low-frequency gain module includes a low-frequency amplifier U3A and a low-frequency switching switch S3. The low-frequency enable module Q1 uses a PMOS transistor, whose enable terminal (gate) receives a low-frequency enable signal. Its source and drain are connected to the power supply (5V) and 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 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 power supply port of the low-frequency amplifier U3A are turned off, thereby disabling the low-frequency gain module.

[0041] Furthermore, the low-frequency amplifier U3A can be selected with... Figure 2 , Figure 3 The various operational amplifiers in the system are of the same or different models. Their positive input terminals are preferably connected to a 1.65V voltage signal to set the DC level of the output signal. The negative input terminal is used to input the signal to be conditioned. A capacitor C3_1 and a resistor R3_2 are connected in series on the negative input terminal. Its output terminal is connected to the low-frequency filter module.

[0042] The low-frequency switching switch S3 is connected between the output and negative input terminals of the low-frequency amplifier U3A. It has three analog input terminals, two digital input terminals, and one analog output terminal. These three analog input terminals are connected through resistors of different values ​​(i.e.,...). Figure 6 The resistors R3_3, R3_4, and R3_5 (from top to bottom) are connected to the negative input terminal of the low-frequency amplifier U3A, and the analog output terminal is connected to the output terminal of the low-frequency amplifier U3A. In addition, the two digital input terminals of the low-frequency switch S3 are used to input the low-frequency gain level signal.

[0043] The low-frequency switching switch can be a switching chip with a switchable function (such as the TS5A3357DCUR single-pole triple-throw switch chip). Its internal logic control module can selectively conduct one of its three analog input terminals and its analog output terminal according to the 0 / 1 status of the two-bit binary low-frequency gain level signal. Since the feedback resistor values ​​connected to different analog input terminals are different, inverting amplifier circuits with different gain factors can be formed to realize the leveled gain of the signal to be conditioned.

[0044] Obviously, the resistance values ​​of 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 it represents. For example, 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, the low-frequency gain level signal generated by the low-frequency control module is [OUT300K0,OUT300K1] = [0,0]. If the analog input terminal S1A of the low-frequency switch S3 is set to be connected to the analog output terminal in this case, the gain factor is the ratio of the resistance value of resistor R3_3 to the resistance value of resistor R3_2. When the amplitude of the low-frequency component detection signal is higher than the second low-frequency threshold voltage and lower than the third low-frequency threshold voltage, the low-frequency gain level signal generated by the low-frequency control module is [OUT2,OUT1]. =[0,1], if the analog input terminal S1B of the low-frequency switch S3 is connected to the analog output terminal in this case, the gain factor is the ratio of the resistance value of resistor R3_4 to the resistance value of 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 module is [OUT2,OUT1] =[1,1]. If the analog input terminal S1C of the low-frequency switch S3 is connected to the analog output terminal in this case, the gain factor is the ratio of the resistance value of resistor R3_5 to the resistance value of resistor R3_2. Obviously, in this connection method, the resistance value of resistor R3_3 should be greater than the resistance value of resistor R3_4, and the resistance value of resistor R3_4 should be greater than the resistance value of resistor R3_5, so as to give a larger gain to the low-frequency component with a smaller amplitude.

[0045] The input of the low-frequency filtering module is connected to the output of the low-frequency gain module. It is used to perform 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 A circuit diagram of the low-frequency filtering module is shown in some optional embodiments. For example... Figure 7 As shown, the low-frequency filtering module consists of cascaded operational amplifiers U4A and U4B and their peripheral circuits forming a two-stage filtering network. After filtering the low-frequency gain signal, the final output is a low-frequency conditioning signal with a frequency of 300KHz.

[0046] The architecture of the high-frequency conditioning unit is similar to that of the low-frequency conditioning unit, such as... Figure 1 As shown, it further includes a high-frequency detection module, a high-frequency control module, a high-frequency enable module, a high-frequency gain module, and a high-frequency filtering module.

[0047] Specifically, the high-frequency detection module converts the signal to be conditioned into a DC high-frequency component detection signal; the high-frequency control module generates a high-frequency control signal based on the amplitude of the high-frequency component detection signal, wherein the high-frequency control signal includes a high-frequency enable signal and a high-frequency gain level signal; the high-frequency enable module enables or disables the high-frequency gain module based on the high-frequency enable signal; when enabled, the high-frequency gain module performs gain leveling on the signal to be conditioned based on the high-frequency gain level signal; and the high-frequency filtering module performs high-frequency filtering on the signal output by the high-frequency gain module and outputs a high-frequency conditioned signal.

[0048] Furthermore, the high-frequency control module includes a first high-frequency comparator, a second high-frequency comparator, and a third high-frequency comparator. The first high-frequency comparator compares the amplitude of the high-frequency component detection signal with a first high-frequency threshold voltage and outputs the comparison result. The second high-frequency comparator compares the amplitude of the high-frequency component detection signal with a second high-frequency threshold voltage and outputs the comparison result. The third high-frequency comparator compares the amplitude of the high-frequency component detection signal with a third high-frequency threshold voltage and outputs the comparison result. The first, second, and third high-frequency threshold voltages increase sequentially. The output of the first high-frequency comparator is used to output a high-frequency enable signal. The outputs of the second and third high-frequency comparators are used to output two-bit binary high-frequency gain level signals.

[0049] Furthermore, the high-frequency gain module includes a high-frequency amplifier and a high-frequency switching switch; the negative input terminal of the high-frequency amplifier is used to input the signal to be conditioned, and the output terminal is connected to the high-frequency filtering module; the high-frequency enable module is connected between the power supply and the power supply port of the high-frequency amplifier; the high-frequency switching switch is connected between the output terminal and the negative input terminal of the high-frequency amplifier, and switches the amplification factor of the high-frequency amplifier on the signal to be conditioned based on the high-frequency gain level signal.

[0050] Furthermore, 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. The two digital input terminals of the high-frequency switching switch are used to input high-frequency gain level signals. Based on the high-frequency gain level signal, the high-frequency switching switch selectively conducts the connection between one of its three analog input terminals and its analog output terminal.

[0051] Figure 8This is a circuit diagram of a high-frequency detection module according to some specific embodiments of this application; Figure 9 This is a schematic diagram of the architecture of a high-frequency control quantity module according to some specific embodiments of this application; Figure 10 The circuit diagrams are provided for a high-frequency gain module and a high-frequency enable module according to some specific embodiments of this application; Figure 11 This is a circuit diagram of a high-frequency filtering module according to some specific embodiments of this application. The specific implementation methods of each module of the high-frequency conditioning unit described above can be referred to the description of the low-frequency conditioning unit, and will not be repeated here.

[0052] Because 3D imaging sonar operates in a complex marine environment, there is noise in various frequency bands. When these noise components contain high-frequency or low-frequency components of the 3D imaging sonar, and their amplitude exceeds the first low-frequency threshold voltage or the first high-frequency threshold voltage, they will be mistakenly identified as effective low-frequency CW signals or effective high-frequency CW signals. This causes both gain filtering channels to be activated simultaneously. Furthermore, because the noise level is low at this time, it may be amplified by a higher gain level, resulting in incorrect gain of the noise components.

[0053] Therefore, in some preferred embodiments, the conditioning circuit is further provided with a latching unit to prevent the low-frequency conditioning unit or the high-frequency conditioning unit from being erroneously turned on.

[0054] Figure 12 The diagram illustrates the architecture of the locking unit and its interaction with the low-frequency enable module and the high-frequency enable module in some preferred embodiments, as shown below. 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 receives a low-frequency component detection signal and a high-frequency component detection signal at its two input terminals, respectively. After comparing the amplitudes of the two signals, it generates and outputs a low-frequency locking signal and a high-frequency locking signal. Based on the received low-frequency locking signal, the low-frequency locking module, in conjunction with the low-frequency enabling module, enables or disables the low-frequency gain module. Similarly, based on the received high-frequency locking signal, the high-frequency locking module, in conjunction with the high-frequency enabling module, enables or disables the high-frequency gain module.

[0055] Figure 13The diagram illustrates the architecture of a latching signal module in a specific embodiment. In this embodiment, the latching signal module consists of a high-frequency / low-frequency component comparator and an inverter. The high-frequency / low-frequency component comparator can be any suitable comparator chip known to those skilled in the art, such as a comparator of the same model as those in the low-frequency control module or the high-frequency control module. Its two input terminals are respectively input to the low-frequency component detection signal and the high-frequency component detection signal (e.g., the positive input terminal inputs the low-frequency component detection signal, and the negative input terminal inputs the high-frequency component detection signal). Its output terminal is divided into two lines, one of which is connected to the inverter (e.g., the line corresponding to the low-frequency latching signal is inverted).

[0056] Therefore, regardless of whether the comparison result of the low-frequency component detection signal and the high-frequency component detection signal is high or low, the low-frequency latch-up signal and the high-frequency latch-up 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 latch-up signal is low and the high-frequency latch-up signal is high. Accordingly, suitable devices such as MOS transistors that can switch on and off states can be selected to construct the low-frequency latch-up module and the high-frequency latch-up module (for example, a PMOS transistor that is turned on at a low level can be used as the low-frequency latch-up module and the high-frequency latch-up module).

[0057] Figure 14 The following diagrams illustrate circuit schematics of the low-frequency gain module, low-frequency enable module, and low-frequency latch-up module in some specific implementations, such as... Figure 14 As shown, the low-frequency latch-up module Q3 uses the same PMOS transistor as the low-frequency enable module Q1. Both are connected in series between the power supply and the power supply port of the low-frequency amplifier U3A. Through their mutual cooperation, they enable or disable the low-frequency gain module. Obviously, this can be referenced... Figure 14 A high-frequency latch-up module is added to the circuit that includes the high-frequency gain module and the high-frequency enable module.

[0058] The following combination Figures 12 to 14 The working principle of the locking unit is explained below: 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 has not emitted an active signal. Since the low-frequency enable module and the high-frequency enable module are turned off at this time, the two gain filter channels are turned off regardless of the level of the lock signal received by the two lock modules.

[0059] 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 is transmitting a low-frequency CW signal and the echo has been identified as containing effective low-frequency CW components. At the same time, the detection results of the high-frequency components show that they do 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. Meanwhile, since the amplitude of the low-frequency component detection signal is also higher than the amplitude of the high-frequency component detection signal, the latching signal module outputs a low-level low-frequency latching signal and a high-level high-frequency latching signal. Therefore, the low-frequency latching module is also turned on. At this time, only low-frequency gain filtering can be performed, while the high-frequency latching module is in the same off state as the high-frequency enable module.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] It should be known that, Figure 13 , Figure 14The 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.

[0064] To verify the performance of the conditioning circuit provided in this application, a function generator XFG1 was used to generate a sweep signal with an amplitude of 100mV from 0 to 650kHz. A Bode analyzer XBP9 was connected to the input and output ports respectively. Figure 15 , Figure 16 The amplitude-frequency characteristics of the low-frequency conditioned signal output from the low-frequency conditioning unit and the high-frequency conditioned signal output from the high-frequency conditioning unit are shown respectively. Figure 15 , Figure 16 It can be seen that the signal gain reached almost 41dB at frequencies of 298kHz and 601kHz.

[0065] The specific embodiments of this application have been described in detail above. For those skilled in the art, several improvements and modifications can be made to this application without departing from the principle of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching of filtering and gain, characterized in that, include: The preamplifier module amplifies the received raw underwater acoustic signal and outputs the signal to be conditioned. The low-frequency conditioning unit is enabled when the signal to be conditioned contains an effective low-frequency CW component, and performs step-by-step gain 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 conditioning signal. The high-frequency conditioning unit is enabled when the signal to be conditioned contains an effective high-frequency CW component, and performs level-by-level gain 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. The output module is used to output the low-frequency conditioning signal or the high-frequency conditioning signal.

2. The dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain as described in claim 1, characterized in that, The low-frequency conditioning unit includes a low-frequency detection module, a low-frequency control module, a low-frequency enable module, a low-frequency gain module, and a low-frequency filtering module. The low-frequency detection module is used to convert the signal to be conditioned into a DC 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 includes a low-frequency enable signal and a low-frequency gain level signal. The low-frequency enable module enables or disables the low-frequency gain module based on the low-frequency enable signal; When enabled, the low-frequency gain module performs gain tiers on the signal to be conditioned based on the low-frequency gain level signal. The low-frequency filtering module is used to perform low-frequency filtering on the signal output by the low-frequency gain module and output the low-frequency conditioning signal.

3. The dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain as described in claim 2, characterized in that, The high-frequency conditioning unit includes a high-frequency detection module, a high-frequency control quantity module, a high-frequency enable module, a high-frequency gain module, and a high-frequency filtering module. The high-frequency detection module is used to convert the signal to be conditioned into a DC high-frequency component detection signal; The high-frequency control quantity module generates a high-frequency control quantity signal based on the amplitude of the high-frequency component detection signal, wherein the high-frequency control quantity signal includes a high-frequency enable signal and a high-frequency gain level signal. The high-frequency enable module enables or disables the high-frequency gain module based on the high-frequency enable signal; When enabled, the high-frequency gain module performs level-based gain on the signal to be conditioned based on the high-frequency gain level signal. The high-frequency filtering module is used to perform high-frequency filtering on the signal output by the high-frequency gain module and output the high-frequency conditioning signal.

4. The dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain as described in claim 2, characterized in that, The low-frequency control module includes a first low-frequency comparator, a second low-frequency comparator, and a third low-frequency comparator. The first low-frequency comparator is used to compare the amplitude of the low-frequency component detection signal with the first low-frequency threshold voltage and output the comparison result; the second low-frequency comparator is used to compare the amplitude of the low-frequency component detection signal with the second low-frequency threshold voltage and output the comparison result; the third low-frequency comparator is used to compare the amplitude of the low-frequency component detection signal with the third low-frequency threshold voltage and output the comparison result; the first low-frequency threshold voltage, the second low-frequency threshold voltage, and the third low-frequency threshold voltage increase sequentially. The output of the first low-frequency comparator is used to output the low-frequency enable signal; The output terminals of the second low-frequency comparator and the third low-frequency comparator are used to output a two-bit binary low-frequency gain level signal.

5. The dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain as described in claim 4, characterized in that, The low-frequency gain module includes a low-frequency amplifier and a low-frequency switching switch; The negative input terminal of the low-frequency amplifier is used to input the signal to be conditioned, and the output terminal is connected to the low-frequency filter module. The low-frequency enable module is connected between the power supply and the power supply port of the low-frequency amplifier. The low-frequency switching switch is connected between the output terminal and the negative input terminal of the low-frequency amplifier, and switches the amplification factor of the low-frequency amplifier for the signal to be conditioned based on the low-frequency gain level signal.

6. The dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain according to claim 5, characterized in that, The low-frequency switching switch has three analog input terminals, two digital input terminals, and one analog output terminal; The three analog input terminals of the low-frequency switch are connected to the negative input terminal of the low-frequency amplifier through resistors with different resistance values. The analog output terminal of the low-frequency switch is connected to the output terminal of the low-frequency amplifier. The two digital input terminals of the low-frequency switch are used to input the low-frequency gain level signal. The low-frequency switching switch selectively connects one of its three analog input terminals to its analog output terminal based on the low-frequency gain level signal.

7. The dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain according to claim 3, characterized in that, The high-frequency control quantity module includes a first high-frequency comparator, a second high-frequency comparator, and a third high-frequency comparator; The first high-frequency comparator is used to compare the amplitude of the high-frequency component detection signal with the first high-frequency threshold voltage and output the comparison result. The second high-frequency comparator is used to compare the amplitude of the high-frequency component detection signal with the second high-frequency threshold voltage and output the comparison result. The third high-frequency comparator is used to compare the amplitude of the high-frequency component detection signal with the third high-frequency threshold voltage and output the comparison result. The first high-frequency threshold voltage, the second high-frequency threshold voltage, and the third high-frequency threshold voltage increase sequentially. The output of the first high-frequency comparator is used to output the high-frequency enable signal; The output terminals of the second and third high-frequency comparators are used to output two-bit binary high-frequency gain level signals.

8. The dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain as described in claim 7, characterized in that, The high-frequency gain module includes a high-frequency amplifier and a high-frequency switching switch; The negative input terminal of the high-frequency amplifier is used to input the signal to be conditioned, and the output terminal is connected to the high-frequency filtering module. The high-frequency enable module is connected between the power supply and the power supply port of the high-frequency amplifier. The high-frequency switching switch is connected between the output terminal and the negative input terminal of the high-frequency amplifier, and switches the amplification factor of the high-frequency amplifier for the signal to be conditioned based on the high-frequency gain level signal.

9. The dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain as described in claim 8, 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 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 switch is connected to the output terminal of the high-frequency amplifier. The two digital input terminals of the high-frequency 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.

10. The dual-frequency CW underwater acoustic signal conditioning circuit with automatic switching filtering and gain according to claim 3, characterized in that, It also includes a locking unit, which comprises: A lock-up signal module is used to compare the amplitudes of the low-frequency component detection signal and the high-frequency component detection signal, and to generate a low-frequency lock-up signal and a high-frequency lock-up signal. A low-frequency lock-up module, based on the low-frequency lock-up signal and in cooperation with the low-frequency enable module, enables or disables the low-frequency gain module. A high-frequency latching module, based on the high-frequency latching signal and in conjunction with the high-frequency enable module, enables or disables the high-frequency gain module; 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 on state does not exceed three.

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