Ultrasonic return signal processing circuit

Abstract

The utility model relates to an ultrasonic return signal processing circuit. The circuit comprises a voltage filtering unit, a primary amplification unit, a band-pass filter unit, a secondary amplification unit, a comparator unit, a power supply unit and a band-pass filter unit. The voltage filtering unit comprises two stages of voltage filtering circuits and can clamp the voltage of an input signal to + / -0.7 V; the first-stage amplification unit is used for primarily amplifying the clamped input signal; the band-pass filter unit carries out parameter matching according to the central frequency point of the ultrasonic transducer, and the central filtering frequency point of the band-pass filter unit is consistent with the working frequency point of the ultrasonic transducer; a feedback circuit of the secondary amplification unit is provided with an adjustable displacement device, and the gain multiple is adjusted according to different strengths of return signals of different ultrasonic transducers; and the comparator unit is used for comparing the amplified signal amplitude with a preset voltage value. The ultrasonic probe is reasonable in design, can be matched with various ultrasonic transducers, and is compact in structure and convenient to use.

Description

Technical Field

[0001] The utility model relates to the field of signal processing circuit design, and in particular to a processing circuit for ultrasonic return signals. Background Art

[0002] At present, ultrasonic detection or flaw detection has become an essential part in the industrial field, and its importance is self-evident. The return signal of ultrasonic waves is an electrical signal converted from ultrasonic wave signals by an ultrasonic transducer. The amplitude of the converted electrical signal is very small, at the millivolt or even microvolt level. Such a low signal amplitude is easily interfered by external signals. For a transceiver-integrated ultrasonic transducer, the excitation signal and the echo signal received by the transducer share the same signal line, and the amplitude of the excitation signal of the ultrasonic transducer is generally relatively large, which further increases the difficulty of processing and identifying the echo signal. Therefore, the processing of the echo signal not only requires filtering out clutter signals, but also requires shielding the large voltage signals on the signal line. Summary of the Utility Model

[0003] The purpose of the utility model is to propose a processing circuit for ultrasonic return signals to process the returned signals so as to filter out noise and clutter and make the signals meet the standard for acquisition. The specific technical solutions adopted are as follows:

[0004] The utility model includes a voltage filtering unit, a first-stage amplification unit, a band-pass filter unit, a second-stage amplification unit, a comparator unit, a power supply unit and a band-pass filter unit;

[0005] The signal input of the voltage filtering unit comes from the electrical signal converted from the sound signal of the ultrasonic transducer. Since the ultrasonic transducer is of the transceiver-integrated type, the input signal of the voltage filtering unit also includes the pulse excitation signal of the ultrasonic wave. The output of the voltage filtering unit is connected to the input of the first-stage amplification unit; the output of the first-stage amplification unit is connected to the input of the band-pass filter unit; the output of the band-pass filter unit is connected to the input of the second-stage amplification unit; the output of the second-stage amplification unit is connected to the input of the comparator unit; the output of the comparator unit is connected to the acoustic time measurement unit for use by the acoustic time measurement unit.

[0006] Preferably, the voltage filtering unit includes diodes D1 to D4, a DC-blocking coupling capacitor C1, diodes D5 to D6, and resistors R1 to R2. The input voltage of the voltage filtering unit is +5V and -5V;

[0007] In the voltage filtering unit, the +5V power supply is connected to the anodes of diodes D1 and D3 through resistor R1. The cathode of diode D1 is connected to the anode of diode D2, the cathode of diode D3 is connected to the anode of diode D4, and the cathodes of diodes D2 and D4 are connected together and then connected to the -5V power supply through resistor R2. The return signal of the ultrasonic transducer is connected to the cathode of diode D1 and the anode of D2 after passing through the DC-blocking capacitor C2. The cathodes of diode D3 and the anode of D4 are connected together and are also connected to the secondary voltage filtering circuit through the DC-blocking capacitor C1. In the secondary voltage filtering circuit, the cathode of diode D5 is connected to one end of the DC-blocking capacitor C1, and the anode of D5 is grounded; the anode of diode D6 is connected to one end of the DC-blocking capacitor C1, and the cathode of D6 is grounded.

[0008] Preferably, a dual-channel amplifier chip is selected to form the primary amplification unit and the secondary amplification unit, and the feedback circuit in the secondary amplification circuit contains an adjustable potentiometer.

[0009] Preferably, the band-pass filter unit includes an inductor and a capacitor, and the center frequency point of the band-pass filter unit is the same as the center frequency point at which the ultrasonic transducer used operates;

[0010] In the band-pass filter unit, the input signal is the output signal of the primary amplification circuit. The band-pass filter unit is composed of an inductor and a capacitor. One end of inductor L1 is connected to the output end of the primary amplification unit, the other end of L1 is connected to one end of capacitor C5, the other end of C5 is respectively connected to one ends of L2 and L3, the other end of L2 is connected to one end of capacitor C6, and the other end of capacitor C6 is the output of the band-pass filter unit; the other end of inductor L3 is connected to capacitor C7, the other end of capacitor C7 is connected to one ends of L4 and C8, and the other ends of L4 and C8 are grounded.

[0011] Preferably, the comparator unit includes a comparator chip and a resistor.

[0012] Preferably, the power supply unit includes a +3.3V power supply output circuit, a +5V power supply output circuit, and a -5V power supply output circuit.

[0013] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0014] The circuit proposed by the present utility model first filters out the high-amplitude voltage contained in the signal, and secondly avoids the damage of large voltage to the subsequent devices.

[0015] In the present utility model, the feedback link of the secondary amplification circuit adopts an adjustable potentiometer, which increases the flexibility of the amplification factor and can adapt to different types of ultrasonic transducers for both transmitting and receiving.

[0016] In the present utility model, the filter used is a band-pass filter, which is convenient for adapting to different ultrasonic transducers and can facilitate parameter adjustment. At the same time, the band-pass filter is arranged between the first-stage amplification unit and the second-stage amplification unit, effectively filtering out out-of-band signals and amplifying in-band signals, which can effectively improve the accuracy of ultrasonic signal detection. Description of the Drawings

[0017] Figure 1 It is the overall circuit block diagram in the embodiment of the present utility model;

[0018] Figure 2 It is the block diagram of the voltage filtering unit in the embodiment of the present utility model;

[0019] Figure 3 It is the block diagram of the first-stage amplification unit in the embodiment of the present utility model;

[0020] Figure 4 It is the block diagram of the band-pass filter unit in the embodiment of the present utility model;

[0021] Figure 5 It is the block diagram of the second-stage amplification unit in the embodiment of the present utility model;

[0022] Figure 6 It is the block diagram of the comparator unit in the embodiment of the present utility model.

[0023] In the figure: 10, voltage filtering unit; 20, first-stage amplification unit; 30, band-pass filter unit; 40, second-stage amplification unit; 50, comparator unit; 60, power supply unit. Detailed Embodiment

[0024] In order to more clearly present the technical problems, technical solutions and beneficial effects to be solved by the present utility model, the following will be described in detail and completely in combination with the drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. Based on the embodiments in the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present utility model.

[0025] A processing circuit for ultrasonic return signals, and its specific embodiment is as Figures 1 to 6 shown: mainly including a voltage filtering unit 10, a first-stage amplification unit 20, a band-pass filter unit 30, a second-stage amplification unit 40, a comparator unit 50, a power supply unit 60 and a band-pass filter unit.

[0026] The signal input of the voltage filtering unit 10 is the electrical signal converted from the ultrasonic signal of the ultrasonic transducer. Since the ultrasonic transducer is integrated for both transmitting and receiving, the input signal of the voltage filtering unit also includes the pulse excitation signal of the ultrasonic wave. The output of the voltage filtering unit 10 is connected to the input of the first-stage amplification unit 20; the output of the first-stage amplification unit 20 is connected to the input of the band-pass filter unit 30; the output of the band-pass filter unit 30 is connected to the input of the second-stage amplification unit 40; the output of the second-stage amplification unit 40 is connected to the input of the comparator unit; the output of the comparator unit is connected to the acoustic time measurement unit for use by the acoustic time measurement unit.

[0027] The voltage filtering unit 10 includes diodes D1~D4, a DC-blocking coupling capacitor C1, diodes D5, D6, and resistors R1, R2. The input voltages of the voltage filtering unit are +5V and -5V. The +5V power supply is connected to the anodes of diodes D1 and D3 through the R1 resistor. The cathode of diode D1 is connected to the anode of diode D2. The cathode of diode D3 is connected to the anode of diode D4. The cathodes of diodes D2 and D4 are connected together and connected to the -5V power supply through the resistor R2. The return signal of the ultrasonic transducer is connected to the cathode of diode D1 and the anode of D2 after passing through the DC-blocking capacitor C2. The cathodes of diodes D3 and D4 are connected together and are connected to the second-stage voltage filtering circuit through the DC-blocking capacitor C1. In the second-stage voltage filtering circuit, the cathode of diode D5 is connected to one end of the DC-blocking capacitor C1, and the anode of D5 is grounded. The anode of diode D6 is connected to one end of the DC-blocking capacitor C1, and the cathode of D6 is grounded. In this embodiment, the model of the diodes D1~D6 selected is B5817W, the capacitance value of C1 is 0.1uF, and the withstand voltage value is 50V; the capacitance value of C2 is 1000pF, and the withstand voltage value is 2KV; the resistance values of resistors R1 and R2 are 2.5kΩ.

[0028] In the embodiment of the present utility model, a dual-channel amplifier chip is selected to form the first-stage amplification unit 20 and the second-stage amplification unit 40. The input signal in the first-stage amplification unit 20 is the output signal of the voltage filtering unit, named output signal 1. One end of output signal 1 is connected to one end of resistor R3, and the other end of R3 is connected to the non-inverting input terminal of the 3rd pin of operational amplifier IC1A. At the same time, the 3rd pin of IC1A is grounded through resistor R4. The power supply of IC1A uses +5V and -5V power supplies simultaneously. The +5V power supply is connected to the 8th pin of the operational amplifier, and the -5V power supply is connected to the 4th pin of the operational amplifier. Filtering capacitors C3 and C4 are respectively connected in parallel at the power supply pins of IC1A. The 1st pin of IC1A is the output of the operational amplifier, which is output signal 2. The 1st pin of the operational amplifier is connected to one end of feedback resistor R5, the other end of R5 is connected to the inverting input terminal of the 2nd pin of IC1A, and is also connected to one end of resistor R6. The other end of R6 is grounded. Resistors R5 and R6 together constitute the feedback link of the operational amplifier. Among them, the resistance value of R3 is required to be within 100Ω, the resistance value of R4 is required to be within 10KΩ, and the resistance ratio of R5 and R6 is less than 5:1. Specifically, in this embodiment, the resistance value of R3 is 22Ω, the resistance value of R4 is 4.7KΩ, the resistance value of R5 is 4.7KΩ, and the resistance value of R6 is 1KΩ; the capacitance values of filtering capacitors C3 and C4 are 0.1uF, and the withstand voltage value is 50V; the model of IC1A is AD8039AR.

[0029] In the second-stage amplification unit 40, its input signal is the output signal of the band-pass filter unit, named output signal 3. One end of output signal 3 is connected to one end of resistor R7, and the other end of R3 is connected to the inverting input terminal of the 6th pin of operational amplifier IC1B. The non-inverting input terminal of the 5th pin of IC1B is grounded through a resistor. The output pin 7 of IC1B is output signal 4. This pin is connected to the 1st and 2nd pins of adjustable potentiometer R10. The 3rd pin of adjustable potentiometer R10 is connected to one end of resistor R9, and is also connected to the 6th pin of IC1B; the other end of R9 is grounded. Adjustable potentiometer R10 and resistor R9 together constitute the feedback link of the second-stage amplification unit. Among them, the resistance of R7 is required to be within 100Ω, the resistance value of R8 is required to be within 10KΩ, and the resistance ratio of R5 and R6 can be adjusted according to the actually used ultrasonic transducer. Specifically, in this embodiment, the resistance value of R7 is 22Ω, the resistance value of R8 is 4.7KΩ, the resistance value of R9 is 1KΩ, and the full-scale resistance value of R10 is 10KΩ.

[0030] The band-pass filter unit includes an inductor and a capacitor. The center frequency point of the band-pass filter unit is consistent with the center frequency point of the ultrasonic transducer used.

[0031] In the band-pass filter unit 30, the input signal is the output signal of the first-stage amplifier circuit 20. The band-pass filter unit is composed of an inductor and a capacitor. One end of the inductor L1 is connected to the output end of the first-stage amplifier unit 20, and the other end of L1 is connected to one end of the capacitor C5. The other end of C5 is respectively connected to one ends of L2 and L3. The other end of L2 is connected to one end of the capacitor C6, and the other end of the capacitor C6 is the output of the band-pass filter unit. The other end of the inductor L3 is connected to the capacitor C7, and the other end of the capacitor C7 is connected to one ends of L4 and C8. The other ends of L4 and C8 are grounded. In this embodiment, the operating frequency of the selected ultrasonic transducer is 2 MHz. Therefore, the center frequency point of the band-pass filter unit also remains at 2 MHz. In this embodiment, after calculation, the value of the inductor L1 and L2 is 33 uH, the value of the capacitors C5 and C6 is 191 pF, the value of the inductor L3 is 4.7 uH, the capacitance value of the capacitor C7 is 1200 pF, the value of the inductor L4 is 800 nH, and the value of the capacitor C8 is 7800 pF.

[0032] The comparator unit 50 is used to compare the maximum amplified signal amplitude with a preset voltage value. The circuit includes a comparator chip, resistors, and filter capacitors. In the circuit, the supply voltage of the comparator chip IC2 is 3.3 V. At the same time, pin 5 of the chip IC2 is pulled up to the 3.3 V power supply through the pull-up resistor R11. One end of the resistor R12 is connected to the 3.3 V power supply, and the other end is connected to pin 4 of IC2 and also connected to one end of the resistor R13. The other end of R13 is grounded. The input signal pin of the comparator is pin 3, and its input signal is the output signal 4 of the second-stage amplifier circuit 40. Inside the chip IC2, the amplitude of the input signal on pin 3 is compared with the amplitude of the preset voltage on pin 4. When the voltage amplitude on pin 3 is greater than the preset voltage value on pin 4, a high level is output from pin 1; when the voltage amplitude on pin 3 is less than the amplitude on pin 4, a low level is output from pin 1. The level output from pin 1 of the chip IC2 is output to the subsequent acoustic time measurement unit for use by the acoustic time measurement unit. In this embodiment, the model selected for IC2 is MAX998EUT, the resistance value of R11 is 4.7 KΩ, the resistance value of R12 is 26 KΩ, and the resistance value of R13 is 10 KΩ.

[0033] In this embodiment, the power supply unit 60 includes a +3.3 V power supply output circuit, a +5 V power supply output circuit, and a -5 V power supply output circuit. Each power supply is completed by a corresponding DCDC power conversion chip.

[0034] The above is only the preferred embodiment of the present invention and is not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A processing circuit for an ultrasonic return signal, characterized in that: It includes a voltage filtering unit (10), a primary amplification unit (20), a secondary amplification unit (40), a comparator unit (50), a power supply unit (60), and a band-pass filter unit; The signal input of the voltage filtering unit (10) is the electrical signal converted from the ultrasonic signal of the ultrasonic transducer. Since the ultrasonic transducer is both a transmitter and a receiver, the input signal of the voltage filtering unit also contains the pulse excitation signal of the ultrasound. The output of the voltage filtering unit (10) is connected to the input of the primary amplification unit (20); the output of the primary amplification unit (20) is connected to the input of the band-pass filter unit; the output of the band-pass filter unit is connected to the input of the secondary amplification unit (40); the output of the secondary amplification unit (40) is connected to the input of the comparator unit; the output of the comparator unit is connected to the subsequent acoustic time measurement unit for use by the acoustic time measurement unit.

2. The processing circuit for an ultrasonic return signal according to claim 1, wherein: The voltage filtering unit (10) includes diodes D1~D4, a DC-blocking coupling capacitor C1, diodes D5~D6, and resistors R1, R2. The input voltage of the voltage filtering unit is +5V and -5V; In the voltage filtering unit, the +5V power supply is connected to the anodes of diodes D1 and D3 through resistor R1. The cathode of diode D1 is connected to the anode of diode D2, the cathode of diode D3 is connected to the anode of diode D4, the cathodes of diodes D2 and D4 are connected together and connected to the -5V power supply through resistor R2; the return signal of the ultrasonic transducer is connected to the cathode of diode D1 and the anode of D2 after passing through the DC-blocking capacitor C2; the cathodes of diode D3 and the anode of D4 are connected together and are simultaneously connected to the secondary voltage filtering circuit through the DC-blocking capacitor C1; in the secondary voltage filtering circuit, the cathode of diode D5 is connected to one end of the DC-blocking capacitor C1, and the anode of D5 is grounded; the anode of diode D6 is connected to one end of the DC-blocking capacitor C1, and the cathode of D6 is grounded.

3. The processing circuit for an ultrasonic return signal according to claim 1, characterized in that: A dual-channel amplifier chip is selected to form the primary amplification unit (20) and the secondary amplification unit (40), and the feedback circuit in the secondary amplification circuit contains an adjustable potentiometer.

4. The processing circuit for an ultrasonic return signal according to claim 1, wherein: The band-pass filter unit includes inductors and capacitors, and the center frequency point of the band-pass filter unit is the same as the center frequency point of the ultrasonic transducer in use; In the band-pass filter unit, the input signal is the output signal of the primary amplification unit (20). The band-pass filter unit is composed of inductors and capacitors. One end of inductor L1 is connected to the output end of the primary amplification unit (20), the other end of L1 is connected to one end of capacitor C5, the other end of C5 is respectively connected to one ends of L2 and L3, the other end of L2 is connected to one end of capacitor C6, and the other end of capacitor C6 is the output of the band-pass filter unit; the other end of inductor L3 is connected to capacitor C7, the other end of capacitor C7 is connected to one ends of L4 and C8, and the other ends of L4 and C8 are grounded.

5. The processing circuit for an ultrasonic return signal according to claim 1, characterized in that: The comparator unit (50) includes a comparator chip and a resistor.

6. The processing circuit for an ultrasonic return signal according to claim 1, wherein: The power supply unit (60) includes a +3.3V power supply output circuit, a +5V power supply output circuit, and a -5V power supply output circuit.

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