CN210953919U - Ultrasonic received signal processing circuit - Google Patents
Ultrasonic received signal processing circuit Download PDFInfo
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- CN210953919U CN210953919U CN201921861242.4U CN201921861242U CN210953919U CN 210953919 U CN210953919 U CN 210953919U CN 201921861242 U CN201921861242 U CN 201921861242U CN 210953919 U CN210953919 U CN 210953919U
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- 238000012545 processing Methods 0.000 title claims abstract description 21
- 230000003321 amplification Effects 0.000 claims abstract description 11
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 11
- 239000003990 capacitor Substances 0.000 claims description 58
- 238000001914 filtration Methods 0.000 claims description 8
- 238000001514 detection method Methods 0.000 abstract description 3
- 239000012530 fluid Substances 0.000 description 4
- 238000013461 design Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000002238 attenuated effect Effects 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
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Abstract
The utility model provides an ultrasonic receiving signal processing circuit; the circuit comprises a pre-amplification circuit, a band-pass filter circuit and a zero-crossing comparison circuit; the utility model discloses a preamplification circuit, band-pass filter circuit and zero passage detection circuit handle the signal to make the receiving transducer receive accurate enlarged signal.
Description
Technical Field
The utility model relates to an ultrasonic wave received signal processing circuit.
Background
The transducer is driven by the transmitting driving circuit to emit ultrasonic pulse signals, the signals are transmitted through a fluid medium to reach a receiving end of the transducer to be received, in the process, due to the fact that the fluid contains a lot of impurities and bubbles, the signal quality can be affected to be greatly attenuated, and the receiving end of the transducer is quite unfavorable for receiving the signals.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem, the utility model provides an ultrasonic wave received signal processing circuit.
The utility model discloses a following technical scheme can realize.
The utility model provides an ultrasonic receiving signal processing circuit; the circuit comprises a pre-amplification circuit, a band-pass filter circuit and a zero-crossing comparison circuit;
the preamplification circuit is connected with the ultrasonic transducer, detects signals of the ultrasonic transducer, amplifies the signals through a triode and inputs the amplified signals to the lower-level processing circuit;
the band-pass filter circuit is connected with the pre-amplification circuit, receives the amplified ultrasonic signal and outputs the filtered ultrasonic signal after passing through the resistor and the capacitor;
the zero-crossing comparison circuit is connected with the band-pass filter circuit, the filtered signal is divided by resistors to adjust threshold voltage of zero-crossing, when the voltage is larger than the threshold value, the triode is conducted to enable the OUTPUT to jump from high level to low level, then the jump signal is transmitted into the DSP, and the DSP carries out interrupt processing.
The pre-amplification circuit comprises a capacitor C1, one end of a capacitor C1 is connected with the ultrasonic transducer, the other end of the capacitor C1 is connected with the base of a triode Q1, the emitter of the triode Q1 is grounded through a resistor R3, the collector of a triode Q1 is connected with a resistor R2, the base of the triode Q1 is further connected with a resistor R2 through a resistor R1, the other end of the resistor R2 is connected with a power supply VCC, the collector of the triode Q1 is further connected with the capacitor C2, and the other end of the capacitor C2 is connected with a band-pass filter circuit.
The band-pass filter circuit comprises a resistor R4, the other end of the resistor R4 is connected with one end of a capacitor C4, a capacitor C3 and a resistor R5 which are connected together, the other end of the resistor R5 is grounded, the other end of the capacitor C3 is connected with a resistor R6, and the other end of the resistor R6 is connected with the other end of a capacitor C4 and serves as an output end for filtering signals.
One end of the capacitor C4, which is connected with the resistor R5, is also connected with the negative electrode of the input end of the amplifier U1, the positive electrode of the input end of the amplifier U1 is grounded through the resistor C5, and the output end of the amplifier U1 is connected with the zero-crossing comparison circuit.
The zero-crossing comparison circuit comprises a capacitor C6, one end of a capacitor C6 is connected with the output end of an amplifier U1, the other end of the capacitor C6 is connected with the anode of a diode D2, the cathode of a diode D2 is connected with a resistor R7, the other end of a resistor R7 is connected with the base of a triode Q2, the collector of the triode Q2 is connected with a power supply VCC through a resistor R9 and is connected to the input end of the DSP signal processor, the cathode of the diode D2 is further connected with the capacitor C7, the other end of the capacitor C7 is connected with the anode of a diode D1, the cathode of a diode D1 is connected with the anode of a diode D2, the base of the triode Q2 is further connected with a resistor R8, and the resistor R8 and the capacitor C7 are.
The beneficial effects of the utility model reside in that: the signals are processed through the pre-amplification circuit, the band-pass filter circuit and the zero-crossing detection circuit, so that the receiving transducer receives accurate amplified signals.
Drawings
Fig. 1 is a schematic structural diagram of the present invention;
fig. 2 is a schematic diagram of an ultrasonic receiving circuit of the present invention;
fig. 3 is a frequency response graph of the filter circuit of the present invention;
fig. 4 is a filtering result curve of the filtering circuit of the present invention.
Detailed Description
The technical solution of the present invention is further described below, but the scope of the claimed invention is not limited to the described.
An ultrasonic received signal processing circuit; the circuit comprises a pre-amplification circuit, a band-pass filter circuit and a zero-crossing comparison circuit;
the preamplification circuit is connected with the ultrasonic transducer, detects signals of the ultrasonic transducer, amplifies the signals through a triode and inputs the amplified signals to the lower-level processing circuit;
the band-pass filter circuit is connected with the pre-amplification circuit, receives the amplified ultrasonic signal and outputs the filtered ultrasonic signal after passing through the resistor and the capacitor;
the zero-crossing comparison circuit is connected with the band-pass filter circuit, the filtered signal is divided by resistors to adjust threshold voltage of zero-crossing, when the voltage is larger than the threshold value, the triode is conducted to enable the OUTPUT to jump from high level to low level, then the jump signal is transmitted into the DSP, and the DSP carries out interrupt processing.
The pre-amplification circuit comprises a capacitor C1, one end of a capacitor C1 is connected with the ultrasonic transducer, the other end of the capacitor C1 is connected with the base of a triode Q1, the emitter of the triode Q1 is grounded through a resistor R3, the collector of a triode Q1 is connected with a resistor R2, the base of the triode Q1 is further connected with a resistor R2 through a resistor R1, the other end of the resistor R2 is connected with a power supply VCC, the collector of the triode Q1 is further connected with the capacitor C2, and the other end of the capacitor C2 is connected with a band-pass filter circuit. The receiving circuit only needs to detect the first edge signal of the received signal of the ultrasonic transducer, so that the design of the amplifying circuit has no high requirement on the amplifying quality of the signal, and only needs to amplify the received signal and then transmit the amplified signal to the next-stage processing circuit, so that a common emitter amplifying circuit is adopted as a pre-amplifying circuit. As shown in fig. 2, after a signal received by the transducer is filtered by a capacitor C1 through a dc signal, the signal is amplified by a cascode amplifier formed by a transistor Q1, and then filtered again by a capacitor C2 through a dc signal, and finally sent to a next-stage processing circuit for band-pass filtering.
The band-pass filter circuit comprises a resistor R4, the other end of the resistor R4 is connected with one end of a capacitor C4, a capacitor C3 and a resistor R5 which are connected together, the other end of the resistor R5 is grounded, the other end of the capacitor C3 is connected with a resistor R6, and the other end of the resistor R6 is connected with the other end of a capacitor C4 and serves as an output end for filtering signals.
Since the frequency of the signal received by the transducer is about 40kHz, the center frequency of the band-pass filter is preferably set to about 40kHz, so that the signal components near the center frequency can be amplified to the maximum extent, and the signals outside the center frequency can be attenuated greatly. An active second-order band-pass filter is selected in the design, a filter prototype of the active second-order band-pass filter is shown in fig. 2, a resistor R4 and a capacitor C3 form a low-pass network, low-frequency signals are allowed to pass, a resistor R5 and a capacitor C4 form a high-pass network, high-frequency signals are allowed to pass, the high-pass network and the high-pass network are connected in series to form a passive band-pass filter circuit, and the center frequency of the band-pass filter circuit can be adjusted by adjusting parameter values of a resistor R4, a capacitor C3.
From the Laplace transform, the S-domain equation set for the filter circuit of FIG. 2 can be derived, where matching of capacitances and simplification of equations are facilitated, let C1＝C2Then, there is:
the circuit transfer function can be solved from the above equation set as:
the center frequency is given by the formula (3.2):
considering that the center frequency of the bandpass filter is about 40kHz, the parameters R1-2 k Ω, R2-350 Ω, R3-240 k Ω, and C are taken1＝C2The frequency response curve of the circuit is shown in fig. 3 at 470pF, and the filtering results are shown in fig. 4.
One end of the capacitor C4, which is connected with the resistor R5, is also connected with the negative electrode of the input end of the amplifier U1, the positive electrode of the input end of the amplifier U1 is grounded through the resistor C5, and the output end of the amplifier U1 is connected with the zero-crossing comparison circuit. Connect a voltage amplifier in band-pass filter circuit's end for keep apart with the load in the band-pass filter shop, the three has constituteed active second order band-pass filter circuit, and voltage amplifier can realize enlargiing to the signal of filtering out simultaneously.
The zero-crossing comparison circuit comprises a capacitor C6, one end of a capacitor C6 is connected with the output end of an amplifier U1, the other end of the capacitor C6 is connected with the anode of a diode D2, the cathode of a diode D2 is connected with a resistor R7, the other end of a resistor R7 is connected with the base of a triode Q2, the collector of the triode Q2 is connected with a power supply VCC through a resistor R9 and is connected to the input end of the DSP signal processor, the cathode of the diode D2 is further connected with the capacitor C7, the other end of the capacitor C7 is connected with the anode of a diode D1, the cathode of a diode D1 is connected with the anode of a diode D2, the base of the triode Q2 is further connected with a resistor R8, and the resistor R8 and the capacitor C7 are.
The key point of the fluid quality measurement in the invention is to measure the forward and backward flow time of sound wave in the fluid, so that accurately capturing the ultrasonic receiving signal is a crucial step for improving the accuracy of the system. It can be known from the design of the transmitting circuit that the frequency of the transmitted ultrasonic signal is relatively stable, and therefore the shape of the signal waveform is also relatively stable, but the waveform of the received signal is deformed to some extent due to the propagation of the ultrasonic wave and the medium factor, and this distorted signal cannot be detected by the threshold setting, that is, a fixed time that is not affected by the waveform shape change needs to be found to receive the signal. Therefore, a zero-crossing comparison circuit is adopted to check the arrival time of the received signal, the threshold voltage is set through the resistance value in the adjusting circuit, and the arrival point of the ultrasonic wave received signal is checked.
As shown in fig. 2, the zero-crossing detection circuit schematic diagram shows that an envelope signal processed by the two-stage band-pass filter circuit passes through a capacitor C6 to remove a dc component, an ac signal continues to be filtered by a capacitor C7 to filter a high-frequency component in the signal, and a low-frequency ac component in the signal continues to pass through each resistor and triode. The circuit utilizes the voltage division principle of a resistor R7 and a resistor R8 to adjust the threshold voltage of zero-crossing triggering. When the voltage at the connection part of the resistor R7 and the resistor R8 and the base electrode of the triode is more than 0.7V, the triode Q2 is conducted, the OUTPUT jumps from high level to low level, then the jump signal is transmitted into the DSP, and the DSP carries out interrupt processing.
The DSP timing interrupt is specifically realized as follows: the signal sent by the transmitting transducer is a periodic signal, the type of the signal is similar to a sine wave, and the sine wave signal is output as a square wave signal after passing through a zero-crossing comparison circuit. When the DSP detects the rising edge of the square wave signal, it triggers a DSP interrupt response. And after the interruption response is started, the DSP timer starts to count time, when the rising edge is detected again, the interruption response stops counting time, and then the interruption response program is closed. Thus the time from transmitting to receiving the transducer can be directly obtained. If the time of one period is too short, the counting number can be set in the DSP, and the timing is stopped when the specified period number is reached.
Claims (5)
1. An ultrasonic received signal processing circuit characterized by: the circuit comprises a pre-amplification circuit, a band-pass filter circuit and a zero-crossing comparison circuit;
the preamplification circuit is connected with the ultrasonic transducer, detects signals of the ultrasonic transducer, amplifies the signals through a triode and inputs the amplified signals to the lower-level processing circuit;
the band-pass filter circuit is connected with the pre-amplification circuit, receives the amplified ultrasonic signal and outputs the filtered ultrasonic signal after passing through the resistor and the capacitor;
the zero-crossing comparison circuit is connected with the band-pass filter circuit, the filtered signal is divided by resistors to adjust threshold voltage of zero-crossing, when the voltage is larger than the threshold value, the triode is conducted to enable the OUTPUT to jump from high level to low level, then the jump signal is transmitted into the DSP, and the DSP carries out interrupt processing.
2. The ultrasonic received signal processing circuit according to claim 1, characterized in that: the pre-amplification circuit comprises a capacitor C1, one end of a capacitor C1 is connected with the ultrasonic transducer, the other end of the capacitor C1 is connected with the base of a triode Q1, the emitter of the triode Q1 is grounded through a resistor R3, the collector of a triode Q1 is connected with a resistor R2, the base of the triode Q1 is further connected with a resistor R2 through a resistor R1, the other end of the resistor R2 is connected with a power supply VCC, the collector of the triode Q1 is further connected with the capacitor C2, and the other end of the capacitor C2 is connected with a band-pass filter circuit.
3. The ultrasonic received signal processing circuit according to claim 1, characterized in that: the band-pass filter circuit comprises a resistor R4, the other end of the resistor R4 is connected with one end of a capacitor C4, a capacitor C3 and a resistor R5 which are connected together, the other end of the resistor R5 is grounded, the other end of the capacitor C3 is connected with a resistor R6, and the other end of the resistor R6 is connected with the other end of a capacitor C4 and serves as an output end for filtering signals.
4. An ultrasonic received signal processing circuit according to claim 3, characterized in that: one end of the capacitor C4, which is connected with the resistor R5, is also connected with the negative electrode of the input end of the amplifier U1, the positive electrode of the input end of the amplifier U1 is grounded through the resistor C5, and the output end of the amplifier U1 is connected with the zero-crossing comparison circuit.
5. The ultrasonic received signal processing circuit according to claim 1, characterized in that: the zero-crossing comparison circuit comprises a capacitor C6, one end of a capacitor C6 is connected with the output end of an amplifier U1, the other end of the capacitor C6 is connected with the anode of a diode D2, the cathode of a diode D2 is connected with a resistor R7, the other end of a resistor R7 is connected with the base of a triode Q2, the collector of the triode Q2 is connected with a power supply VCC through a resistor R9 and is connected to the input end of the DSP signal processor, the cathode of the diode D2 is further connected with the capacitor C7, the other end of the capacitor C7 is connected with the anode of a diode D1, the cathode of a diode D1 is connected with the anode of a diode D2, the base of the triode Q2 is further connected with a resistor R8, and the resistor R8 and the capacitor C7 are.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921861242.4U CN210953919U (en) | 2019-10-31 | 2019-10-31 | Ultrasonic received signal processing circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921861242.4U CN210953919U (en) | 2019-10-31 | 2019-10-31 | Ultrasonic received signal processing circuit |
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| CN210953919U true CN210953919U (en) | 2020-07-07 |
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| CN201921861242.4U Expired - Fee Related CN210953919U (en) | 2019-10-31 | 2019-10-31 | Ultrasonic received signal processing circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113504307A (en) * | 2021-09-10 | 2021-10-15 | 西南石油大学 | Multi-frequency core sound velocity measuring device |
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2019
- 2019-10-31 CN CN201921861242.4U patent/CN210953919U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113504307A (en) * | 2021-09-10 | 2021-10-15 | 西南石油大学 | Multi-frequency core sound velocity measuring device |
| CN113504307B (en) * | 2021-09-10 | 2021-12-21 | 西南石油大学 | Multi-frequency core sound velocity measuring device |
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Granted publication date: 20200707 |