Transmit / receive and isolation circuit for a sonar probe

Abstract

The application provides a kind of sounder probe's receiving / transmitting and isolation circuit, including control and signal processing unit, ultrasonic transducer, transmitting signal amplification circuit, active Balun circuit, power amplifier circuit, receiving / transmitting isolation circuit, program-controlled weak signal amplification circuit, band-pass filter and level matching circuit.The application introduces active Balun circuit after transmitting signal amplification circuit, converts single-ended excitation signal into differential signal with equal amplitude and 180° phase difference, and cooperates differential power amplifier circuit to drive ultrasonic transducer, improves driving efficiency, effectively suppresses common-mode interference, and improves the anti-interference ability of system.The application introduces active Balun circuit after transmitting signal amplification circuit, converts single-ended excitation signal into differential signal with equal amplitude and 180° phase difference, and cooperates differential power amplifier circuit to drive ultrasonic transducer, improves driving efficiency, effectively suppresses common-mode interference, and improves the anti-interference ability of system.

Description

Technical Field

[0001] This invention belongs to the field of sonar detection technology, specifically a sonar detector's transmit / receive and isolation circuit, used to enable ultrasonic transducers to transmit and receive under high-voltage excitation conditions. Background Technology

[0002] Ultrasonic detection technology is widely used in ultrasonic ranging, ultrasonic imaging, non-destructive testing, and underwater detection. In practical applications, ultrasonic transducers typically need to withstand high-amplitude drive signals during the transmission phase to obtain sufficient power, while in the reception phase, they need to perform high-sensitivity detection of echo signals with extremely small amplitudes. Therefore, this places high demands on the switching and isolation of the circuit system between transmission and reception.

[0003] In existing technologies, ultrasonic transducers typically employ a separate transmit and receive structure, or use relays, analog switches, T / R switches, or other methods to achieve transmit-receive switching. These solutions generally suffer from the following problems: firstly, high-voltage transmit signals can easily intrude into the receive channel, causing damage or performance degradation to the receiving circuit components; secondly, mechanical relays are bulky and have slow response times, while semiconductor switches lack reliability under high voltage and high current conditions and have complex circuit structures.

[0004] Furthermore, in applications of differential high-voltage driven ultrasonic transducers, traditional transceiver / isolation schemes struggle to balance high-voltage suppression capabilities with the transmission performance of weak echo signals, often resulting in insufficient protection during the transmission phase or introducing significant signal attenuation and distortion during the reception phase.

[0005] Therefore, there is an urgent need for a transceiver circuit that is compact, highly reliable, and capable of safely multiplexing the transmitting and receiving functions of an ultrasonic transducer under high-voltage differential driving conditions. Summary of the Invention

[0006] This invention proposes a sonar detector's transmit / receive and isolation circuit. Through a reasonable circuit structure design, it achieves safe multiplexing of the ultrasonic transducer's transmitting and receiving functions under high-amplitude differential driving conditions, avoids the influence of high-voltage transmitting signals on the receiving circuit, and improves the system's reliability and stability.

[0007] The technical solution to achieve the purpose of this invention is as follows: a sonar detector's transmit / receive and isolation circuit, comprising: a control and signal processing unit, an ultrasonic transducer, a transmit signal amplification circuit, an active balun circuit, a power amplification circuit, a transmit / receive isolation circuit, a programmable weak signal amplification circuit, a bandpass filter, and a level matching circuit, wherein:

[0008] The control and signal processing unit generates an excitation signal and inputs it to the transmit signal amplification circuit. The transmit signal amplification circuit amplifies the transmit excitation signal from the control and signal processing unit. The Balun circuit performs differential processing on the amplified transmit signal to obtain a pair of differential drive signals with equal amplitude and opposite phase. The power amplification circuit amplifies the differential drive signal to output a high-amplitude differential drive signal. During the transmission phase, the high-amplitude differential drive signal output by the power amplification circuit is input to the ultrasonic transducer via the transceiver / isolation circuit to drive the ultrasonic transducer to emit ultrasonic waves. The ultrasonic transducer converts the amplified differential drive signal into ultrasonic waves and radiates them outward during the transmission phase, and converts the received ultrasonic echo into an electrical signal for output during the receiving phase.

[0009] The transceiver / isolation circuit is located between the power amplifier circuit and the programmable weak signal amplifier circuit. It is used to isolate, limit the current and limit the amplitude of the high-amplitude drive signal during the transmission phase; and to allow the weak echo signal output by the ultrasonic transducer to be transmitted to the receiving channel during the receiving phase, thereby achieving effective isolation and safe multiplexing between the transmission and receiving channels.

[0010] The programmable weak signal amplification circuit is used to perform multi-stage low-noise amplification of the weak echo signal transmitted through the transceiver / isolation circuit.

[0011] The bandpass filter is used to select the frequency band and suppress noise of the echo signal after multi-stage low-noise amplification; the level matching circuit is used to adjust the amplitude and match the level of the filtered echo signal; the control and signal processing unit is used to acquire, convert analog to digital and process the echo signal, and extract the target echo features based on the propagation time and signal strength information of the echo signal, thereby obtaining the target distance information and target spatial distribution information to realize the detection of underwater targets.

[0012] Compared with the prior art, the significant advantages of this invention are:

[0013] (1) This invention introduces an active Balun circuit after the transmitting signal amplification circuit to convert the single-ended excitation signal into a differential signal with equal amplitude and 180° phase difference, and uses it in conjunction with a differential power amplifier circuit to drive the ultrasonic transducer, thereby improving the driving efficiency and effectively suppressing common-mode interference, thus enhancing the anti-interference capability of the system; (2) The use of a power amplifier circuit structure enhances the differential signal driving, making it suitable for high-voltage ultrasonic detection applications; (3) This invention sets up a clamping circuit 1, a limiting circuit, and a clamping circuit 2 between the power amplifier circuit and the programmable weak signal amplification circuit. The transmit / receive isolation circuit is composed of a high-amplitude differential signal that is limited and clamped during the transmission phase and a weak echo signal that is protected during the reception phase, effectively reducing the impact of residual high voltage signal in the transmission channel on the receiving channel; (4) The transmit and receive functions can be multiplexed without the use of mechanical relays or high-speed analog switches, the circuit structure is simple, the response speed is fast, and the reliability is high; (5) The receiving channel adopts a multi-stage programmable low-noise amplification and bandpass filtering structure, which can effectively improve the signal-to-noise ratio of the echo signal while ensuring high sensitivity; (6) The transmission, isolation and receiving circuits work together to ensure high power transmission performance while taking into account the detection requirements of weak echo signals, the overall system has high stability and strong adaptability; (7) The present invention adopts a compact structure, is easy to use, and has high reliability, and is suitable for sonar detection applications with high requirements for reliability and stability.

[0014] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0015] Figure 1 This is a block diagram of the overall structure of the transmit / receive and isolation circuit of a sonar detector.

[0016] Figure 2 It is a signal amplification circuit.

[0017] Figure 3 It is an active balun circuit and a power amplifier circuit.

[0018] Figure 4 This is a schematic diagram of a transmit / receive isolation circuit.

[0019] Figure 5 It is a programmable weak signal amplifier circuit.

[0020] Figure 6 It is a bandpass filter and level matching circuit. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0022] Combination Figure 1 A sonar detector's transmit / receive and isolation circuit includes a control and signal processing unit, an ultrasonic transducer, a transmit signal amplification circuit, an active balun circuit, a power amplification circuit, a transmit / receive isolation circuit, a programmable weak signal amplification circuit, a bandpass filter, and a level matching circuit. Wherein:

[0023] The control and signal processing unit performs the system's control and signal processing functions. It generates the transmission excitation signal required for ultrasonic detection and acquires, processes, and analyzes the received ultrasonic echo signals. The output of the control and signal processing unit is connected to the input of the transmission signal amplification circuit, sending the transmission excitation signal to the transmission channel.

[0024] The transmit signal amplification circuit amplifies the low-amplitude transmit excitation signal from the control and signal processing unit. Since the amplitude of the excitation signal output by the control and signal processing unit is low and cannot directly meet the driving requirements of subsequent circuits, the transmit signal amplification circuit pre-amplifies the transmit excitation signal to improve the signal amplitude and driving capability. Amplifying the transmit excitation signal effectively improves the stability of signal transmission and provides stable input conditions for subsequent signal conversion. The output of the transmit signal amplification circuit is connected to the input of a Balun circuit, allowing the amplified transmit signal to be input to the Balun circuit for differential processing.

[0025] The balun circuit is used to perform differential conversion processing on the single-ended signal output from the transmitting signal amplifier circuit, converting the single-ended signal into a pair of differential drive signals with equal amplitude and opposite phase. By setting up the balun circuit, the conversion from single-ended signal to differential signal can be realized, thereby effectively suppressing common-mode interference during signal transmission and improving the system's anti-interference capability and signal transmission stability. Simultaneously, the differential drive mode can provide a symmetrical and stable input signal to the subsequent power amplifier circuit, which is beneficial to improving the operating efficiency and output performance of the power amplifier circuit. The output terminal of the balun circuit is connected to the input terminal of the power amplifier circuit, used to input the differential drive signal to the power amplifier circuit for further amplification.

[0026] The power amplifier circuit amplifies the differential drive signal generated by the Balun circuit to output a high-amplitude differential drive signal. During the transmission phase, the high-amplitude differential drive signal output by the power amplifier circuit is input to the ultrasonic transducer via the transceiver / isolation circuit, driving the ultrasonic transducer to emit ultrasonic waves. By employing a differential power amplifier structure, the output drive capability can be improved while reducing the impact of noise and interference on the system, thereby improving the system's reliability.

[0027] The ultrasonic transducer is used to convert differential drive electrical signals into ultrasonic waves and radiate them outward during the transmission phase, and to convert the received ultrasonic echoes into electrical signals for output during the reception phase. The ultrasonic transducer is connected to the transmission channel and the reception channel respectively through the transceiver / isolation circuit, so that the transmission channel and the reception channel can be multiplexed on the same ultrasonic transducer.

[0028] The transceiver / isolation circuit is located between the power amplifier circuit and the programmable weak signal amplifier circuit. It is used to isolate, limit the current and amplitude of the high-amplitude drive signal during the transmission phase to prevent the high-voltage signal from directly entering the receiving channel. During the receiving phase, the transceiver / isolation circuit allows the weak echo signal output by the ultrasonic transducer to be transmitted to the receiving channel, thereby achieving effective isolation and safe multiplexing between the transmission and receiving channels.

[0029] The programmable weak signal amplification circuit is used to perform multi-stage low-noise amplification of the weak echo signal transmitted through the transceiver / isolation circuit, thereby improving the amplitude and signal-to-noise ratio of the echo signal. The output terminal of the programmable weak signal amplification circuit is connected to the bandpass filter.

[0030] The bandpass filter is used for frequency band selection and noise suppression of the amplified echo signal. By filtering the echo signal, it retains the effective signal components that match the operating frequency of the ultrasonic transducer and suppresses out-of-band noise, thereby improving the signal-to-noise ratio of the echo signal. The output of the filter circuit is connected to the level matching circuit.

[0031] The level matching circuit is used to adjust the amplitude and match the level of the filtered echo signal to meet the input level requirements of the control and signal processing unit. The control and signal processing unit is used to acquire, convert analog to digital and process the echo signal, and extract target echo features based on the propagation time and signal strength information of the echo signal, thereby obtaining the target's distance information and spatial distribution information to achieve underwater target detection.

[0032] Furthermore, the signal amplification circuit uses the high-speed operational amplifier chip AD817.

[0033] Furthermore, the power amplifier circuit uses the power amplifier chip PA107DP.

[0034] Furthermore, the programmable weak signal amplification circuit selects a low-noise amplifier as the first stage and a programmable gain amplifier as the second stage.

[0035] Furthermore, the filtering circuit uses an operational amplifier chip with excellent performance to construct a bandpass filter of 250kHz to 350kHz, which simultaneously performs level shifting and buffered output. By filtering the signal, it retains the effective signal components that match the operating frequency of the ultrasonic transducer, and converts the signal after dual power supply amplification into a single power supply output form, adjusting the signal amplitude to the required voltage range, such as 0 to 2000mV, to meet the input requirements of the subsequent signal processing section.

[0036] Combination Figure 2 The transmitted signal amplification circuit employs a multi-stage operational amplifier cascade structure to form a preamplifier unit, used for multi-stage amplification of the low-amplitude transmitted excitation signal from the control and signal processing unit. The initial excitation signal from the control unit (usually a small-amplitude pulse or a specific waveform) is input to the first-stage operational amplifier for preliminary voltage amplification. Each subsequent operational amplifier circuit further amplifies the signal, progressively increasing the signal amplitude by appropriately configuring the gain of each stage until it reaches the level required to drive the subsequent active balun circuit. The relationship between the output signal Vout1 and the input signal Vin is as follows: .

[0037] Combination Figure 3 The active Balun circuit converts the single-ended signal Vout1 output from the transmitting signal amplifier circuit into a differential signal with equal amplitude and a 180° phase difference; the relationship between the output signal and the input signal Vout1 is as follows: The above structure enables differential drive while ensuring stable signal amplitude amplification, providing good input conditions for the subsequent power amplifier circuit and effectively suppressing common-mode interference. The power amplifier circuit amplifies the differential drive signal output from the active Balun circuit to obtain a high-amplitude differential excitation signal that meets the driving requirements of the ultrasonic transducer. A PA107DP power amplifier chip is used to construct the differential power amplifier structure, and the relationship between the output signal and the input signal is as follows: The power amplifier circuit significantly improves the output voltage amplitude and driving capability while maintaining the differential signal characteristics, thereby effectively driving the ultrasonic transducer to emit ultrasonic waves during the transmission phase. The differential power amplifier structure not only increases output energy but also reduces the impact of external interference and system noise on the transmitted signal, improving the overall stability and reliability of the system. Through this structure, differential driving can be achieved while ensuring stable signal amplitude amplification, providing good input conditions for subsequent power amplifier circuits and effectively suppressing common-mode interference.

[0038] Combination Figure 4The transmit / receive isolation circuit is located between the power amplifier circuit and the programmable weak signal amplifier circuit. It is used to isolate the high-voltage transmission signal from interference and damage that may occur to the receiving channel. During the receiving stage, the signal can be smoothly transmitted to the programmable weak signal amplifier circuit through the transmit / receive isolation circuit, realizing safe transmit and receive multiplexing of the same transducer.

[0039] The transmit / receive isolation circuit includes a clamping circuit 1, a limiting circuit, and a clamping circuit 2 connected in sequence.

[0040] The clamping circuit 1 includes two sets of symmetrical diodes respectively disposed on the two paths of the differential drive signal. Specifically, the anode of diode D8 and the cathode of diode D7 are connected to the output terminal. Connect the cathode of diode D8 and the anode of diode D7 to the output terminal. Connections: The anode of diode D10 and the cathode of diode D9 are connected to the output terminal. Connect the cathode of diode D10 and the anode of diode D9 to the output terminal. Connection. All diodes in clamping circuit 1 are Schottky diodes. During the receiving phase, when a weak echo signal is input, clamping circuit 1 quickly clamps the abnormally high voltage signal, thereby preventing residual high voltage signals or transient interference signals from the transmitting channel from entering the programmable weak signal amplification circuit, and avoiding the weak echo signal being submerged.

[0041] The limiting circuit includes series power resistors and parallel capacitors respectively disposed on the two differential drive signal paths, and a set of symmetrical diodes disposed between the two signal paths.

[0042] Specifically, power resistor R36 is connected in series in the OUT3+ signal path, and power resistor R40 is connected in series in the OUT3− signal path; capacitor C29 is connected in parallel across power resistor R36, and capacitor C36 is connected in parallel across power resistor R40, thus forming an RC buffer network; diodes D3 and D4 are connected in reverse parallel between the two differential signals to symmetrically limit the differential signals. All diodes in the limiting circuit are Schottky diodes. During the transmission phase, when a high-amplitude differential transmission signal passes through, the power resistors are used to share some of the energy and limit transient current, while the RC network buffers signal spikes. The symmetrical diodes conduct when the voltage exceeds a threshold, limiting the signal amplitude, thereby reducing the impact of high-voltage signals on subsequent circuits and improving the stability and reliability of the system.

[0043] The clamping circuit 2 is located between the limiting circuit and the input terminal of the programmable weak signal amplification circuit to further clamp and protect the differential signal. Specifically, it includes connecting the positive terminal OUT3+ of the differential signal to the input terminal IN+ after passing through the limiting circuit, and placing diodes D1 and D2 between the input terminal IN+ and GND, wherein diodes D1 and D2 are connected in anti-parallel. The negative terminal OUT3− of the differential signal is connected to the input terminal IN− after passing through the limiting circuit, and placing diodes D5 and D6 between the input terminal IN− and GND, wherein diodes D5 and D6 are connected in anti-parallel. All diodes in the clamping circuit 2 are Schottky diodes. During the transmission phase, the high-amplitude differential signal is further clamped, limiting the signal voltage within a preset range to achieve dual protection for the programmable weak signal amplification circuit.

[0044] The symmetrical limiting and clamping units utilize diodes with sufficiently high withstand voltages to ensure safe operation of the limiting unit under the influence of high-amplitude differential signals during the transmission phase. These diodes typically have a withstand voltage of no less than 200V. This structure effectively isolates the transmitted high-voltage signal from the received weak signal without affecting the echo signal reception sensitivity, thus improving the system's reliability and stability.

[0045] Combination Figure 5 The programmable weak signal amplification circuit employs differential coupling at its input. This differential coupling introduces the weak echo signal output from the ultrasonic transducer into the receiving channel, isolating the DC component and suppressing common-mode noise, thus ensuring a higher signal-to-noise ratio and stability during subsequent amplification. The programmable weak signal amplification circuit performs multi-stage low-noise amplification on the weak ultrasonic echo signal transmitted through the transceiver / isolation circuit to improve signal amplitude and signal-to-noise ratio. The circuit consists of two stages: the first stage uses a low-noise amplifier with a gain set to 8; the second stage uses a programmable gain amplifier, the gain of which is also adjusted by the control and signal processing unit. This structure allows for dynamic adjustment of the receiving gain according to different detection conditions, improving the system's adaptability to varying echo intensities.

[0046] Combination Figure 6 The bandpass filter is used for frequency band selection and noise suppression of the amplified echo signal. The bandpass filter employs an active bandpass filter structure, with a passband range of 250kHz to 350kHz to match the operating frequency of the ultrasonic transducer. Furthermore, the level matching circuit converts the dual-supply amplified signal into a single-supply output form and adjusts the signal amplitude to the required voltage range to meet the input requirements of subsequent signal processing circuits.

[0047] The above-described embodiments are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the 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 modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A sonar detector's transmit / receive and isolation circuit, characterized in that, include: The system includes a control and signal processing unit, an ultrasonic transducer, a transmit signal amplification circuit, an active balun circuit, a power amplification circuit, a transmit / receive isolation circuit, a programmable weak signal amplification circuit, a bandpass filter, and a level matching circuit, among which: The control and signal processing unit generates an excitation signal and inputs it to the transmit signal amplification circuit. The transmit signal amplification circuit amplifies the transmit excitation signal from the control and signal processing unit. The Balun circuit performs differential processing on the amplified transmit signal to obtain a pair of differential drive signals with equal amplitude and opposite phase. The power amplification circuit amplifies the differential drive signal to output a high-amplitude differential drive signal. During the transmission phase, the high-amplitude differential drive signal output by the power amplification circuit is input to the ultrasonic transducer via the transceiver / isolation circuit to drive the ultrasonic transducer to emit ultrasonic waves. The ultrasonic transducer converts the amplified differential drive signal into ultrasonic waves and radiates them outward during the transmission phase, and converts the received ultrasonic echo into an electrical signal for output during the receiving phase. The transceiver / isolation circuit is located between the power amplifier circuit and the programmable weak signal amplifier circuit, and is used to isolate, current limit, and amplitude limit the high-amplitude drive signal during the transmission phase. This is used to allow the weak echo signal output by the ultrasonic transducer to be transmitted to the receiving channel during the receiving phase, thereby achieving effective isolation and secure multiplexing between the transmitting and receiving channels; The programmable weak signal amplification circuit is used to perform multi-stage low-noise amplification of the weak echo signal transmitted through the transceiver / isolation circuit. The bandpass filter is used to select the frequency band and suppress noise of the echo signal after multi-stage low-noise amplification; the level matching circuit is used to adjust the amplitude and match the level of the filtered echo signal; the control and signal processing unit is used to acquire, convert analog to digital and process the echo signal, and extract the target echo features based on the propagation time and signal strength information of the echo signal, thereby obtaining the target distance information and target spatial distribution information to realize the detection of underwater targets.

2. The sonar detector's transmit / receive and isolation circuit according to claim 1, characterized in that, The transmitted signal amplification circuit adopts a multi-stage operational amplifier cascade structure to form a preamplifier unit.

3. The sonar detector's transmit / receive and isolation circuit according to claim 1, characterized in that, The transmit / receive isolation circuit includes a clamping circuit 1, a limiting circuit, and a clamping circuit 2 connected in sequence. The clamping circuit 1 includes two sets of symmetrical diodes respectively disposed on the two differential drive signal paths. During the receiving phase, when a weak echo signal is input, the clamping circuit 1 quickly clamps the abnormally high voltage signal. The limiting circuit includes a series power resistor and a parallel capacitor respectively disposed on the two differential drive signal paths, and a set of symmetrical diodes is disposed between the two signals. The clamping circuit 2 is disposed between the limiting circuit and the input terminal of the programmable weak signal amplification circuit, and is used to further clamp and protect the differential signal.

4. The sonar detector's transmit / receive and isolation circuit according to claim 3, characterized in that, Both clamping circuit 1 and clamping circuit 2 use Schottky diodes.

5. The sonar detector's transmit / receive and isolation circuit according to claim 1, characterized in that, The transmitted signal amplification circuit uses the high-speed operational amplifier chip AD817.

6. The sonar detector's transmit / receive and isolation circuit according to claim 1, characterized in that, The power amplifier circuit uses the power amplifier chip PA107DP.

7. The sonar detector's transmit / receive and isolation circuit according to claim 1, characterized in that, The programmable weak signal amplification circuit selects a low-noise amplifier as the first stage and a programmable gain amplifier as the second stage.

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