A method and system for suppressing transducer tailing applied to depth sounding

Abstract

The application relates to the field of acoustic electronic technology and discloses a transducer tailing suppression method and system applied to depth measurement. In view of the problem that the tailing signal after the transducer emission in a transceiving combined system leads to receiving limiting and increases the ranging blind area, the application carries out low-resistance discharge reset on the matching network and the transducer respectively after the emission pulse ends. The starting time of the discharge reset is dynamically determined based on the actual emission signal envelope detected at the transducer end. Specifically, the emission signal is sampled at the transducer end and envelope detection is carried out, when the end time of the signal envelope is detected, after a preset delay, low-impedance discharge is synchronously carried out on the matching network energy storage element and the transducer through a bidirectional electronic switch circuit. The application can adaptively calibrate the reset time, accurately suppress the tailing and effectively reduce the depth measurement blind area.

Description

Technical Field

[0001] This invention relates to the field of acoustic electronics technology, and in particular to a transducer tailing suppression method and system for depth sounding. Background Technology

[0002] In acoustic depth sounding systems employing combined transceiver transducers, after the transducer finishes transmitting, a continuously decaying oscillating signal, known as a trailing signal, appears at both ends of the transducer due to the transducer's own mechanical inertia, parasitic parameters of the drive circuit, and the freewheeling effect of reactive energy storage components (such as inductors and capacitors) in the matching network. Since the receiving circuit in a combined transceiver system must immediately switch to receiving mode after transmission, the high-amplitude trailing signal can easily exceed the dynamic range of the receiving front end, causing amplitude limiting in the receiving channel. This masks the echo signal from nearby targets, increases the minimum measurable distance, and creates a depth sounding blind zone.

[0003] One known suppression method involves designing the drive pulse at the transmitter source as a Gaussian envelope signal to reduce sidelobes in the transmitted spectrum and soften the signal cutoff edge. However, this method cannot completely eliminate the tailing caused by the energy-stored matching network and the transducer's own damped oscillations. Another approach involves connecting a resonant circuit in series in the matching network and then momentarily short-circuiting the transducer or energy storage element via a switch to reset it, thereby accelerating tail attenuation. However, if the reset circuit is connected too early, the trailing edge of the effective transmitted pulse will be truncated, resulting in a narrower actual transmitted pulse width and a loss of transmitted energy. If it is connected too late, the tailing has already formed and entered the receiving window, significantly reducing the suppression effect. Typically, the reset time is fixed relative to a fixed delay at the transmitter source. However, due to factors such as the transducer's operating environment and impedance variations, there is an uncertain delay between the actual time when the transmitted signal arrives at the transducer and establishes its envelope and the source-end drive signal. The fixed delay method cannot accurately match the actual pulse end time, creating a contradiction between tail suppression effect and transmitted power loss. Summary of the Invention

[0004] This invention provides a transducer tail suppression method and system for depth sounding. It addresses the problems of existing technologies being unable to completely suppress tailing and having difficulty in accurately determining the reset intervention point for tail suppression. This results in problems such as premature intervention causing narrowing of the actual transmission pulse width and power loss, and late intervention leading to poor suppression effect and inability to effectively reduce the blind zone.

[0005] The core technology of this invention is to extract the envelope of the transmitted signal in real time at the transducer end, dynamically determine the end time of the envelope as the delay reference, and then perform independent low-impedance discharge reset on the matching network and the transducer after the reference, thereby accurately suppressing the trailing.

[0006] In a first aspect, the present invention provides a transducer tail suppression method for depth sounding, applied to a transceiver combined system including a matching network and a transducer, the method comprising the following steps:

[0007] After the transmission pulse ends, the matching network and transducer are reset by low-resistance discharge. The timing of the discharge reset is dynamically determined based on the actual transmitted signal envelope detected at the transducer end.

[0008] Furthermore, the timing for dynamically determining the discharge reset initiation includes: The transmitted signal is sampled at the transducer end, and its signal envelope is obtained through the envelope detection circuit. Once the end of the signal envelope is detected, a preset delay is performed to initiate a discharge reset.

[0009] Furthermore, the envelope detection circuit includes: A precision rectifier circuit is used to rectify the sampled signal; A low-pass filter circuit is used to filter the rectified signal to obtain the signal envelope; A comparator is used to compare the signal envelope with a reference level and generate a level transition signal that characterizes the start and end times of the envelope.

[0010] Furthermore, the low-resistance discharge reset of the matching network and the transducer is achieved through a first discharge circuit and a second discharge circuit, respectively; the first discharge circuit is connected in parallel across the energy storage element of the matching network, and the second discharge circuit is connected in parallel across the transducer.

[0011] Furthermore, the first discharge circuit and / or the second discharge circuit are bidirectional electronic switch circuits, which form a low-impedance AC discharge loop when turned on.

[0012] Furthermore, the bidirectional electronic switching circuit includes: Two MOSFETs, with their sources connected to each other and their drains serving as the two ports of a switch, or with their drains connected to each other and their sources serving as the two ports of a switch. An isolation driver is used to receive a control enable signal and synchronously drive two MOSFETs to turn on.

[0013] Furthermore, an MCU receives the signal output from the envelope detection circuit to detect the end time of the signal envelope and control the preset delay; during the MCU's discharge reset, it shields against any further interruptions caused by the envelope detection circuit until the next transmission cycle.

[0014] Furthermore, the peripheral circuitry of the isolation driver includes a gate resistor for controlling the rise and fall speeds of the switch, and a resistor connected in parallel between the gate and source of the MOSFET to reduce impedance.

[0015] Furthermore, the matching network is an LC series resonant network, and the discharge reset is achieved by shorting the capacitor and / or inductor in the LC series resonant network.

[0016] Secondly, the present invention provides a transducer tail suppression system for depth sounding, comprising: Matched filter network and transducer; The sampling module is used to acquire the transmitted sampling signal at the transducer end; The detection module is used to detect the transmitted sampled signal to calibrate the end time of the envelope of the transmitted pulse at the transducer end; The control module is used to determine the reset intervention time based on the envelope end time and output a reset control signal; The reset module includes a first discharge circuit and a second discharge circuit connected in parallel to the matched filter network and the transducer, respectively. The reset module responds to the reset control signal and performs low-impedance discharge reset on the matched filter network and the transducer.

[0017] The main contributions and innovations of this invention are as follows: 1. Significantly shorten the depth sounding blind zone and increase the minimum measurable distance: By simultaneously performing low-impedance discharge dual reset on the matching network and transducer, the residual oscillation energy is forced to decay rapidly, effectively suppressing the tail amplitude and duration, enabling the receiving channel to receive near-range echoes earlier and significantly shortening the depth sounding blind zone.

[0018] 2. Dynamically adjust the reset timing to avoid transmission energy loss and suppression effect degradation: The reset delay start point is determined based on the actual transmission signal envelope directly detected at the transducer end, which overcomes the signal delay uncertainty caused by the matching network, transducer impedance changes, etc., and ensures that the reset action is always initiated only after the effective transmission pulse has completely ended. This avoids truncating the normal transmission pulse width and can suppress it immediately when the tail first appears, achieving optimal timing matching.

[0019] 3. Enhanced system environmental adaptability and reliability: The reset timing does not depend on fixed preset parameters, but automatically adjusts according to actual working conditions to adapt to changes in transducer characteristics caused by different water depths, temperatures, etc. At the same time, the interrupt shielding mechanism prevents echoes or noise from falsely triggering the reset logic, ensuring stable system operation.

[0020] 4. Simple circuit implementation and flexible control: The dual reset discharge uses a bidirectional electronic switch with isolation drive, which can independently reset the matching network and transducer with only a single control signal. In addition, parameters such as discharge resistor can be adjusted by software, which is convenient for porting and parameter optimization to different platforms.

[0021] Details of one or more embodiments of the present invention are set forth in the following drawings and description, so that other features, objects and advantages of the invention will be more readily understood. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a system implementation block diagram of a transducer tail suppression method for depth sounding according to the present invention; Figure 2 This is a schematic diagram of the corresponding reset signal timing control; Figure 3 The bidirectional electronic switch architecture used in the reset circuit is shown. Figure 4 This is a schematic diagram showing the parallel connection positions of two sets of bidirectional electronic switches in the system; Figure 5 A detailed circuit diagram of the system (including the discharge circuit, matching network, and transducer); Figure 6 The corresponding discharge drive and precision envelope detector circuit diagram is shown below. Figure 7 This is a flowchart of the MCU firmware interrupt handling process. Figure 8 This is a waveform diagram showing the trailing effect without the trailing suppression function applied. Figure 9 The waveform diagram after applying the tail suppression function. Detailed Implementation

[0023] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with one or more embodiments of this specification. Rather, they are merely examples of apparatuses and methods consistent with some aspects of one or more embodiments of this specification as detailed in the appended claims.

[0024] It should be noted that the steps of the corresponding methods are not necessarily performed in the order shown and described in this specification in other embodiments. In some other embodiments, the methods may include more or fewer steps than described in this specification. Furthermore, a single step described in this specification may be broken down into multiple steps in other embodiments; and multiple steps described in this specification may be combined into a single step in other embodiments.

[0025] See Figure 1-6 This invention provides a transducer tail suppression system for depth sounding. The sampling module, consisting of a sampling transformer T1 and surrounding resistor R12, is used to acquire the transmitted sampling signal from the transducer. The detection module, consisting of a precision rectifier circuit (U2, U3, D1, D2, etc.), a low-pass filter (R15, C7), and a comparator U4, is used to perform envelope detection on the sampled signal and calibrate the start time. The control module, implemented by an MCU, determines the reset intervention time based on the calibrated start time and a preset pulse width and outputs a reset control signal, also known as a discharge control signal (CTRLIN). The reset module includes a first discharge circuit (connected in parallel to a matched filter network) and a second discharge circuit (connected in parallel to the transducer), which executes a double reset discharge action in response to the discharge control signal (CTRLIN).

[0026] This embodiment uses a 65kHz single-frequency depth sounding application as an example. At the operating point, the impedance of transducer Y1 is approximately 9kΩ, and the matching network adopts an LC series resonant matching form, where the inductor L1 is 2.3mH and the capacitor C3 is 22nF.

[0027] See Figure 1 and Figure 4 The system of this invention consists of a transmitter, a matched filter (i.e., a matching network), a transducer, an envelope detection unit, an MCU controller, a Reset circuit 1 (i.e., a first discharge circuit), and a Reset circuit 2 (i.e., a second discharge circuit). The transmitter generates a transmission signal with the required frequency and pulse width, which drives the transducer Y1 after impedance transformation by the matched filter. To quickly suppress tail oscillations after transmission, the system sets up two independent reset discharge channels: Reset circuit 1 is connected in parallel across the energy storage element of the matched filter network, and Reset circuit 2 is connected in parallel across the transducer Y1. The MCU monitors the actual transmission signal envelope at the transducer in real time through the envelope detection unit, dynamically determines the reset intervention time accordingly, and outputs a discharge control signal (CTRLIN) to synchronously control the two sets of reset circuits to perform a dual reset action.

[0028] See Figure 2 The dynamic timing control mechanism of the present invention is described in detail below: The transmitter generates a drive signal at time t1. Due to the capacitive and inductive load characteristics of the matching network L1, C3, and transducer Y1, there is an inherent transmission delay ΔT1 between the transmitted signal at both ends of the transducer and the source signal. A valid transmitted signal envelope is only detected at the transducer end at time t2. If a fixed delay method (based on t1) is used, the variable delay ΔT1, which is affected by changes in the operating environment impedance, cannot be compensated for, leading to inaccurate reset timing: early intervention will truncate the effective transmitted pulse width, while delayed intervention will result in the tail entering the receiving window. This invention uses a sampling transformer T1 (turns ratio 1:100, withstand voltage 300V) at the transducer end to acquire the transducer end voltage in real time. After passing through a precision envelope detection circuit, a level transition signal characterizing the start of the envelope is generated and sent to the MCU. After the MCU captures the transition signal, it calibrates this moment as time t2 (i.e., the pulse start point). Then, using t2 as a reference, it delays for the known duration of the transmitted signal until time t3, and outputs a discharge control signal (CTRLIN) with a pulse width of ΔT2, initiating a dual reset. Since the starting reference t2 is detected in real time, and the delay pulse width is a known precise value, the entire timing can automatically follow the actual operating conditions of the transducer to dynamically compensate for the transmission delay, and ensure that the reset action intervenes immediately after the transmission ends, fundamentally solving the drawback of inaccurate timing in the fixed delay method.

[0029] See Figure 3 Both Reset circuit 1 and Reset circuit 2 employ a bidirectional electronic switch architecture, enabling bidirectional low-impedance discharge of AC tail signals. Taking a set of bidirectional electronic switches as an example, it includes two MOSFETs (NMOSFETs) Q2 and Q4, and two isolation drivers (Isolation Driver 1 and Isolation Driver 2). The sources of Q2 and Q4 are interconnected, with their drains serving as connection points 1 and 2 of the switch, respectively; or their drains are interconnected, with their sources serving as two ports. The inputs of Isolation Driver 1 and Isolation Driver 2 share the same enable discharge control signal (CTRLIN) from the MCU. When the discharge control signal (CTRLIN) is high, Isolation Driver 1 and Isolation Driver 2 output drive signals to the gates of Q2 and Q4, respectively, turning on both transistors simultaneously. Since Q2 and Q4 are connected in reverse series, regardless of the instantaneous polarity of the voltage between connection point 1 and connection point 2, current can form a low-impedance path through the channel of one MOSFET and the body diode of the other MOSFET, thus achieving true bidirectional short-circuit discharge of AC signals. An isolation driver is used to electrically isolate the low-voltage control signals on the MCU side from the high voltage of the power circuit. The MCU only needs to send a single discharge control signal (CTRLIN) to complete the control of the entire discharge function, which is simple and reliable.

[0030] See Figure 4The two sets of bidirectional electronic switches are connected in parallel in the system as follows: Reset circuit 1 (i.e., the first discharge circuit) is directly connected in parallel to the energy storage elements of the matched filter network—namely, the two ends of the series resonant branches L1 and C3; Reset circuit 2 (i.e., the second discharge circuit) is directly connected in parallel to the two ends of the input terminal of transducer Y1. The two discharge circuits are electrically independent of each other, and can quickly dissipate the residual energy in the matched network and the transducer through their respective low-resistance discharge paths, thereby realizing the dual reset function of the present invention, which performs low-resistance discharge reset on the matched network and the transducer respectively.

[0031] See Figure 5 and Figure 6 The system provides a detailed circuit implementation method.

[0032] The MCU generates two complementary push-pull signals, which are sent to driver U1 (model 2EDL23N06PJ). U1 drives a half-bridge circuit consisting of MOSFETs Q1 (IRFS4115) and Q3 (IRFS4115) and capacitors C1 and C2 (0.47μF / 2kV MLCC capacitors). The half-bridge output drives transducer Y1 after passing through a matching filter network (inductor L1, capacitor C3).

[0033] In the bleeder circuit section, the first bleeder circuit is connected in parallel across the matched filter network, and consists of MOSFETs Q5 (IRFS4115) and Q6 (IRFS4115) and a power bleeder resistor R6 (22Ω / 50W) forming a bidirectional electronic switch branch. The second bleeder circuit is connected in parallel across the transducer Y1, and consists of MOSFETs Q2 (IRFS4115) and Q4 (IRFS4115) and a power bleeder resistor R1 (100Ω / 100W) forming a bidirectional electronic switch branch. The resistance values ​​of R6 and R1 are selected based on the principle that the discharge time constant of their respective bleeder circuits should be much smaller than the natural decay time of the trailing signal, and long-term reliable operation is ensured through power derating.

[0034] The discharge drive circuit consists of four isolation drivers U5 to U8 (model 1ED020I12-F) and their peripheral circuitry. Figure 6In the diagram, drivers 1-4 have the same structure, so only driver 1 is shown. They drive MOSFETs Q2, Q4, Q5, and Q6 respectively. Diodes D3-D6 are used for short-circuit detection when the bidirectional switching device is an IGBT. Capacitors C11, C13, C17, and C19 are used to filter out glitches in the drive signal. Resistors R19, R21, R23, and R25 are gate series resistors used to control the rise and fall speeds of the MOSFETs during turn-on and turn-off, suppressing voltage overshoot during switching. Resistors R20, R22, R24, and R26 are connected in parallel between the gate and source of each MOSFET to reduce the gate-source impedance and prevent induced voltage from causing the MOSFET to falsely turn on when the gate is floating. The input signals for all isolated drivers come from the same MCU-generated discharge control signal (CTRLIN), enabling synchronous control of the two discharge circuits and four MOSFETs.

[0035] In the envelope detection section, sampling transformer T1 (turns ratio 1:100, withstand voltage 300V) steps down the high-voltage transmitted signal from transducer Y1 for sampling. Resistor R12 is connected in parallel to the primary side of T1 to reduce the input impedance. The sampled signal is fed into a precision rectifier circuit consisting of operational amplifiers U2 (OP27GSZ) and U3 (OP27GSZ), rectifier diodes D1 (1N4007) and D2 (1N4007), and thin-film resistors R8-R11 and R13 for envelope detection. The rectified pulse signal is filtered by a low-pass filter consisting of resistor R15 and capacitor C7 to obtain a smooth signal envelope. This envelope signal is then input to the non-inverting input of comparator U4 (TL331IDR) and compared with the DC bias reference level set by resistors R17, R18, and capacitor C8. When the envelope signal amplitude exceeds the reference level, comparator U4 outputs a high level; when the envelope signal amplitude falls back below the reference level, comparator U4 outputs a low level. Therefore, the digital transition signal output by the comparator represents the start and end times of the transmit pulse envelope applied to the transducer. This signal is connected to an I / O port of the MCU configured as an external interrupt input.

[0036] See Figure 7The interrupt handling process within the MCU is as follows: After each transmission mission, the MCU first clears a reset status flag to allow responses to discharge reset requests within the current transmission cycle. When the MCU's external interrupt input port detects a level transition signal from comparator U4 (i.e., the envelope end time), it first checks whether the reset status flag is cleared. If it is cleared, an interrupt response is initiated, and the discharge control signal (CTRLIN) is output high, enabling Reset circuit 1 and Reset circuit 2 to perform discharge reset actions, which are released after a duration of ΔT2. Simultaneously with entering interrupt handling, the MCU sets the reset status flag, thereby shielding against any subsequent interrupts caused by echo signals or noise within the current transmission cycle. Interrupt response is only reopened after the MCU clears the reset status flag again in the next transmission cycle. This mechanism effectively prevents accidental reset actions during reception, ensuring the stable and reliable operation of the system.

[0037] Figure 8 The waveform at the transducer end is shown when the tail suppression function is not applied. It can be seen that after the transmission pulse ends, there is a high-amplitude, continuously decaying tail oscillation at both ends of the transducer. This tail will cause the receiving channel to be limited within the receiving window, forming a large depth sounding blind zone. Figure 9 The waveform after applying the tail suppression function of this embodiment is shown. After the actual end time of the transmitted pulse is dynamically determined by precision envelope detection, the discharge control signal (CTRLIN) triggers the bidirectional electronic switch to conduct at time t3. The residual energy in the matching network and transducer is rapidly discharged through R6 and R1, respectively, and the tail oscillation is quickly suppressed. Experimental results confirm that at a working frequency of 65kHz, the present invention shortens the dead zone caused by the tail by about 0.5ms, effectively increasing the shortest measurable distance. The discharge duration ΔT2 can be flexibly adjusted by MCU software to adapt to different application scenarios such as matching network parameters, transducer type, and transmitted signal strength.

[0038] Those skilled in the art should understand that the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0039] The above embodiments are merely illustrative of several implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the appended claims.

Claims

1. A transducer tail suppression method for depth sounding, applied to a transceiver combined system including a matching network and a transducer, characterized in that, include: After the transmission pulse ends, the matching network and the transducer are respectively reset by low-resistance discharge. The timing of the discharge reset is dynamically determined based on the actual transmitted signal envelope detected at the transducer end. Specifically, it includes: sampling the transmitted signal at the transducer end and obtaining its signal envelope through an envelope detection circuit; and after detecting the end time of the signal envelope, initiating the discharge reset after a preset delay.

2. The transducer tail suppression method according to claim 1, characterized in that, The envelope detection circuit includes: A precision rectifier circuit is used to rectify the sampled signal; A low-pass filter circuit is used to filter the rectified signal to obtain the signal envelope; A comparator is used to compare the signal envelope with a reference level to generate a level transition signal characterizing the start and end times of the envelope.

3. The transducer tail suppression method according to claim 1, characterized in that, The low-resistance discharge reset of the matching network and the transducer is achieved by a first discharge circuit and a second discharge circuit, respectively; the first discharge circuit is connected in parallel across the energy storage element of the matching network, and the second discharge circuit is connected in parallel across the transducer.

4. The transducer tail suppression method according to claim 3, characterized in that, Both the first and second discharge circuits are bidirectional electronic switch circuits, and when the bidirectional electronic switch circuits are turned on, they form a low-impedance AC discharge loop.

5. The transducer tailing suppression method according to claim 4, characterized in that, The bidirectional electronic switch circuit includes: Two MOSFETs, with their sources connected to each other and their drains serving as the two ports of a switch, or with their drains connected to each other and their sources serving as the two ports of a switch. An isolation driver is used to receive a control enable signal and synchronously drive the two MOS transistors to turn on.

6. The transducer tail suppression method according to claim 1, characterized in that, An MCU receives the signal output from the envelope detection circuit to detect the end time of the signal envelope and control the preset delay; during the MCU's discharge reset, any further interruptions caused by the envelope detection circuit are blocked until the next transmission cycle.

7. The transducer tailing suppression method according to claim 5, characterized in that, The peripheral circuitry of the isolation driver includes a gate resistor for controlling the rise and fall speeds of the switch, and a resistor connected in parallel between the gate and source of the MOS transistor to reduce impedance.

8. The transducer tailing suppression method according to claim 1, characterized in that, The matching network is an LC series resonant network, and the discharge reset is achieved by shorting the capacitor and / or inductor in the LC series resonant network.

9. A transducer tail suppression system for depth sounding, characterized in that, include: Matched filter network and transducer; A sampling module is used to acquire the transmitted sampling signal at the transducer end; The detection module is used to perform detection processing on the transmitted sampling signal to calibrate the envelope end time of the transmitted pulse at the transducer end; The control module is used to determine the reset intervention time based on the envelope end time and output a reset control signal; The reset module includes a first discharge circuit and a second discharge circuit connected in parallel to the matched filter network and the transducer, respectively. The reset module responds to the reset control signal to perform low-impedance discharge reset on the matched filter network and the transducer.

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