Pulse amplification circuit based on pressure sensor and pulse signal acquisition system

Abstract

The utility model belongs to the technical field of human body pulse detection, and discloses a pulse amplifying circuit based on a pressure sensor and a pulse signal acquisition system, and the circuit comprises the pressure sensor, a first-stage amplifying circuit, a second-stage amplifying circuit, a third-stage amplifying circuit, a fourth-stage amplifying circuit and a reference circuit, the signal input end of the first-stage amplification circuit receives an original pulse signal output by a pressure sensor and then outputs a differential amplification signal, the signal input end of the second-stage amplification circuit receives the differential amplification signal and then suppresses a common-mode signal and outputs a second amplification signal, and the signal input end of the third-stage amplification circuit receives the second amplification signal and then outputs the third amplification signal. The isolated direct current passes through a signal and outputs an alternating current signal in a following mode, a fourth-stage amplifying circuit receives the alternating current signal and then amplifies and filters the alternating current signal, and an amplified pulse signal is obtained and output. According to the utility model, the cost of the product is reduced, the circuit is simplified, the practicability is enhanced, and the pulse signal can be accurately measured.

Description

Technical Field

[0001] The utility model belongs to the technical field of human pulse detection, and relates to a pulse amplification circuit and a pulse signal acquisition system based on a pressure sensor. Background Technique

[0002] Pulse is a common physiological phenomenon and an external reflection of important physiological information such as the state of the heart and blood vessels. Therefore, pulse signal detection not only provides physiological reference information for blood pressure measurement, blood flow measurement and other physiological detections, but also the pulse signal itself can give a lot of diagnostically valuable information.

[0003] In the prior art, optical sensors are usually used to collect pulse signals. The optical sensors capture pulse signals by detecting the change in light absorption caused by blood flow. However, the amplitude of such signals is usually at the microvolt level, and weak signals are easily interfered by environmental light fluctuations, skin surface reflection differences and motion artifacts. Moreover, in order to amplify and identify weak signals, multiple-stage high-gain amplifiers, filtering modules and analog-to-digital conversion circuits are required, resulting in an increase in hardware volume and power consumption. This poses challenges to the battery life and miniaturization design of portable or wearable devices.

[0004] A pressure sensor is a sensor used to measure pressure changes. It can directly detect the minute pressure changes of pulse vibrations. When subjected to pressure, the metal inside the pressure sensor undergoes elastic deformation, resulting in a change in the internal resistance of the pressure sensor, and finally converting it into an output electrical signal. Therefore, it is of great significance to design a new pulse amplification circuit based on a pressure sensor. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a pulse amplification circuit based on a pressure sensor, aiming to solve the problems in the prior art that the pulse amplification circuit uses an optical sensor to collect pulse signals, and the circuit structure is complex, resulting in an increase in hardware volume and power consumption;

[0006] Another purpose of the utility model is to provide a pulse signal acquisition system.

[0007] The technical solutions adopted by the utility model to achieve the above purposes are as follows:

[0008] A pulse amplification circuit based on a pressure sensor includes a pressure sensor and an amplification circuit based on the pressure sensor. The amplification circuit based on the pressure sensor includes a first-stage amplification circuit, a second-stage amplification circuit, a third-stage amplification circuit, a fourth-stage amplification circuit and a reference circuit;

[0009] The pressure sensor uses piezoresistive strain gauges, and its signal output terminal outputs the original pulse signal to the first-stage amplification circuit. After the signal input terminal of the first-stage amplification circuit receives the original pulse signal, it outputs a differential amplification signal. After the signal input terminal of the second-stage amplification circuit receives the differential amplification signal, it suppresses the common-mode signal and outputs a second amplified signal. After the signal input terminal of the third-stage amplification circuit receives the second amplified signal, it passes through isolation DC and outputs an AC signal through signal following. After the fourth-stage amplification circuit receives the AC signal, it performs amplification and filtering to obtain the amplified pulse signal and outputs it;

[0010] The reference signal output terminal of the reference circuit is used to output a reference voltage to the reference signal input terminal of the second-stage amplification circuit.

[0011] As a limitation, the first-stage amplification circuit includes a first operational amplifier and a second operational amplifier;

[0012] The positive input terminal of the first operational amplifier serves as the first input terminal of the first-stage amplification circuit and is connected to the negative output terminal of the pressure sensor. The positive input terminal of the second operational amplifier serves as the second input terminal of the first-stage amplification circuit and is connected to the positive output terminal of the pressure sensor. The negative input terminal of the first operational amplifier and the negative input terminal of the second operational amplifier are connected in series through a fourth resistor. At the same time, the negative input terminal of the first operational amplifier is also connected to its own output terminal through a third resistor, and the negative input terminal of the second operational amplifier is also connected to its own output terminal through a second resistor. The output terminal of the first operational amplifier is connected in series with a first resistor and serves as the first output terminal of the first-stage amplification circuit. The output terminal of the second operational amplifier is connected in series with a radio frequency resistor and serves as the second output terminal of the first-stage amplification circuit;

[0013] The positive power supply terminal of the second operational amplifier is connected to the power supply, and the negative power supply terminal is grounded.

[0014] As a second limitation, the second-stage amplification circuit includes a third operational amplifier;

[0015] The negative input terminal of the third operational amplifier serves as the first input terminal of the second-stage amplification circuit and is connected to the first output terminal of the first-stage amplification circuit. The positive input terminal of the third operational amplifier serves as the second input terminal of the second-stage amplification circuit and is connected to the second output terminal of the first-stage amplification circuit. The output terminal of the third operational amplifier serves as the output terminal of the second-stage amplification circuit and is connected to the input terminal of the third-stage amplification circuit;

[0016] The positive input terminal of the third operational amplifier is connected in series with a fifth resistor and then connected to the reference signal output terminal of the reference circuit. The negative input terminal is connected in series with a sixth resistor and then connected to its own output terminal;

[0017] The positive power supply terminal of the third operational amplifier is connected to the power supply, and the negative power supply terminal is grounded.

[0018] As a third limitation, the third-stage amplifier circuit includes a first voltage follower formed by a fourth operational amplifier;

[0019] The positive input terminal of the first voltage follower is sequentially connected in series with a tenth resistor and a first capacitor and then serves as the input terminal of the third-stage amplifier circuit to be connected to the output terminal of the second-stage amplifier circuit. The middle node of the series circuit of the tenth resistor and the first capacitor is grounded through a twelfth resistor; the output terminal of the first voltage follower serves as the output terminal of the third-stage amplifier circuit; the positive power supply terminal of the first voltage follower is connected to the power supply, and the negative power supply terminal is grounded.

[0020] As a fourth limitation, the fourth-stage amplifier circuit includes a second voltage follower formed by a fifth operational amplifier;

[0021] The positive input terminal of the second voltage follower is sequentially connected in series with a thirteenth resistor and an eleventh resistor and then serves as the input terminal of the fourth-stage amplifier circuit to be connected to the output terminal of the third-stage amplifier circuit. The middle node connected to the positive input terminal of the thirteenth resistor and the second voltage follower is grounded through a third capacitor, and the middle terminal connected to the thirteenth resistor and the eleventh resistor is grounded through a second capacitor; the output terminal of the second voltage follower serves as the output terminal of the fourth-stage amplifier circuit to output the amplified pulse signal.

[0022] As a fifth limitation, the reference circuit includes a sixth operational amplifier;

[0023] The positive input terminal of the sixth operational amplifier is connected to an external power supply after being connected in series with a seventh resistor, and is also grounded through a parallel circuit of an eighth resistor and a ninth resistor connected in series; the output terminal of the sixth operational amplifier serves as the reference signal output terminal of the reference circuit and is connected to the reference signal input terminal of the second-stage amplifier circuit.

[0024] As a sixth limitation, the pressure sensor is an FS19 pressure sensor.

[0025] The present invention also provides a pulse signal acquisition system, including the above-mentioned pulse amplifier circuit based on a pressure sensor, a signal acquisition unit for converting an analog signal into a digital signal, a signal processing unit, and a host computer;

[0026] The pulse amplifier circuit based on a pressure sensor amplifies the original pulse signal obtained by the pressure sensor, obtains the amplified pulse signal and outputs it to the signal acquisition unit. The signal acquisition unit converts the amplified pulse signal into a digital signal after receiving it, and the output terminal of the signal acquisition unit outputs the digital signal to the signal processing unit. The signal processing unit processes the digital signal and then sends it to the host computer.

[0027] Due to the adoption of the above technical solutions, compared with the prior art, the technical progress achieved by the present utility model is as follows:

[0028] (1) The pulse amplification circuit based on a pressure sensor of the present utility model includes a pressure sensor and an amplification circuit based on the pressure sensor. The amplification circuit based on the pressure sensor includes a first to fourth stage amplification circuit and a reference circuit. Among them, the signal input terminal of the first stage amplification circuit receives the original pulse signal output by the pressure sensor and then outputs a differential amplification signal. After the signal input terminal of the second stage amplification circuit receives the differential amplification signal, it suppresses the common-mode signal and outputs a second amplified signal. After the signal input terminal of the third stage amplification circuit receives the second amplified signal, it passes through isolation and DC blocking and outputs an AC signal through signal following. After the fourth stage amplification circuit receives the AC signal, it performs amplification and filtering to obtain the amplified pulse signal. The present utility model processes and amplifies the original pulse signal through four-stage amplification circuits, making the original pulse signal easier to collect and having a lower distortion rate. Compared with the existing optical sensor that requires a multi-stage high-gain amplifier, a filtering module, and an analog-to-digital conversion circuit to collect the pulse signal, the four-stage amplification circuit adopted by the present utility model has a simple circuit structure, reduces costs, reduces the hardware volume, and reduces power consumption.

[0029] (2) In the present utility model, a pressure sensor is used to obtain the original pulse signal. The pressure sensor uses a piezoresistive strain gauge fabricated by micro-machining. Compared with the optical sensor, using a pressure sensor is not affected by ambient light and the skin surface reflection difference, reduces the influence of motion artifacts, has a simpler circuit and thus a smaller volume and lower power consumption.

[0030] (3) The pulse signal acquisition system in the present utility model includes a pulse amplification circuit based on a pressure sensor, a signal acquisition unit, a signal processing unit, and a host computer. Among them, the amplified pulse signal output by the pulse amplification circuit based on the pressure sensor has a large amplitude waveform and is easier to be collected by the signal acquisition unit.

[0031] In summary, the present utility model reduces the cost of the product, simplifies the circuit, enhances the practicability, and is beneficial to accurately measuring the pulse signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Shown is the circuit schematic diagram of the pulse amplification circuit based on a pressure sensor in Embodiment 1 of the present utility model;

[0033] Figure 2 Shown is the circuit schematic diagram of the reference circuit in Embodiment 1 of the present utility model;

[0034] Figure 3 Shown is the simulation comparison diagram obtained in Embodiment 1 of the present utility model;

[0035] Figure 4 Shown is the structural block diagram of the pulse signal acquisition system in Embodiment 2 of the present utility model. Detailed implementation manners

[0036] For better explaining the present utility model and facilitating understanding, the present utility model will be described in detail below with reference to the accompanying drawings through specific implementation manners.

[0037] Embodiment 1

[0038] As Figure 1 shown, this embodiment is a pulse amplification circuit based on a pressure sensor, including a pressure sensor and an amplification circuit based on the pressure sensor. The amplification circuit based on the pressure sensor includes a first-stage amplification circuit, a second-stage amplification circuit, a third-stage amplification circuit, a fourth-stage amplification circuit, and a reference circuit.

[0039] The pressure sensor uses a piezoresistive strain gauge, and its signal output terminal outputs an original pulse signal to the first-stage amplification circuit. After receiving the original pulse signal, the signal input terminal of the first-stage amplification circuit outputs a differential amplification signal. After receiving the differential amplification signal, the signal input terminal of the second-stage amplification circuit suppresses the common-mode signal and outputs a second amplified signal. After receiving the second amplified signal, the signal input terminal of the third-stage amplification circuit passes through isolation and outputs an AC signal through signal following. After receiving the AC signal, the fourth-stage amplification circuit performs amplification and filtering to obtain an amplified pulse signal; the reference signal output terminal of the reference circuit is used to output a reference voltage to the reference signal input terminal of the second-stage amplification circuit.

[0040] In this embodiment, the first-stage amplification circuit includes a first operational amplifier U1 and a second operational amplifier U2; the positive input terminal of the first operational amplifier U1 serves as the first input terminal of the first-stage amplification circuit and is connected to the negative output terminal of the pressure sensor. The positive input terminal of the second operational amplifier U2 serves as the second input terminal of the first-stage amplification circuit and is connected to the positive output terminal of the pressure sensor. A fourth resistor R4 is connected in series between the negative input terminal of the first operational amplifier U1 and the negative input terminal of the second operational amplifier U2. At the same time, the negative input terminal of the first operational amplifier U1 is also connected to its own output terminal through a third resistor R3, and the negative input terminal of the second operational amplifier U2 is also connected to its own output terminal through a second resistor R2; the output terminal of the first operational amplifier U1 is connected in series with a first resistor R1 and serves as the first output terminal of the first-stage amplification circuit, which is connected to the first input terminal of the second-stage amplification circuit; the output terminal of the second operational amplifier U2 is connected in series with a radio frequency resistor RF and serves as the second output terminal of the first-stage amplification circuit, which is connected to the second input terminal of the second-stage amplification circuit; the positive power supply terminal of the second operational amplifier U2 is connected to the power supply, and the negative power supply terminal is grounded.

[0041] In this embodiment, the pressure sensor is an FS19 pressure sensor. The FS19 pressure sensor adopts the proven micro-melt sensor technology, which originates from the demanding aerospace and automotive application fields. It uses a micro-machined piezoresistive strain gauge, which is fused to a high-performance stainless steel load cell elastomer through high-temperature glass bonding. This sensing technology abandons the aging-sensitive organic epoxy resin used in traditional load cell designs, thus possessing excellent long-term stability. The elastomer is precision machined to ensure excellent consistency of each component.

[0042] The FS19 pressure sensor uses resistors Rt1, Rt3, Rc2, and Rc4 to form a resistance bridge. It adopts a full-bridge design with a low output impedance and good symmetry, and can detect minute pressure changes of pulse vibrations.

[0043] Among them, the negative output terminal of the FS19 pressure sensor is connected to the positive input terminal of the first operational amplifier U1, the positive output terminal of the FS19 pressure sensor is connected to the positive input terminal of the second operational amplifier U2, the positive input terminal of the FS19 pressure sensor is connected to the power supply, and the negative input terminal of the FS19 pressure sensor is grounded.

[0044] The second-stage amplification circuit includes a third operational amplifier U3; the inverting input terminal of the third operational amplifier U3 serves as the first input terminal of the second-stage amplification circuit and is connected to the first output terminal of the first-stage amplification circuit, the non-inverting input terminal of the third operational amplifier U3 serves as the second input terminal of the second-stage amplification circuit and is connected to the second output terminal of the first-stage amplification circuit, and the output terminal of the third operational amplifier U3 serves as the output terminal of the second-stage amplification circuit and is connected to the input terminal of the third-stage amplification circuit; the non-inverting input terminal of the third operational amplifier U3 is connected to the reference signal output terminal of the reference circuit after being connected in series with a fifth resistor R5, and the inverting input terminal is connected to its own output terminal after being connected in series with a sixth resistor R6; the positive power supply terminal of the third operational amplifier U3 is connected to the power supply, and the negative power supply terminal is grounded.

[0045] As Figure 2 shown, the reference circuit includes a sixth operational amplifier U6; the non-inverting input terminal of the sixth operational amplifier U6 is respectively connected to one end of a seventh resistor R7, one end of an eighth resistor R8, and one end of a ninth resistor R9. The other end of the ninth resistor R9 and the other end of the eighth resistor R8 are grounded, and the other end of the seventh resistor R7 is connected to the power supply; the output terminal of the sixth operational amplifier U6 serves as the reference signal output terminal of the reference circuit and is connected to the reference signal input terminal of the second-stage amplification circuit.

[0046] In this embodiment, the third-stage amplifier circuit includes a first voltage follower composed of a fourth operational amplifier U4. The positive input terminal of the first voltage follower is sequentially connected in series with a tenth resistor R10 and a first capacitor C1 and then serves as the input terminal of the third-stage amplifier circuit to be connected to the output terminal of the second-stage amplifier circuit. The intermediate terminal where the tenth resistor R10 and the first capacitor C1 are connected is grounded through a twelfth resistor R12. The output terminal of the first voltage follower serves as the output terminal of the third-stage amplifier circuit to be connected to the input terminal of the fourth-stage amplifier circuit. The positive power supply terminal of the first voltage follower is connected to the power supply, and the negative power supply terminal is grounded.

[0047] The fourth-stage amplifier circuit includes a second voltage follower composed of a fifth operational amplifier U5. The positive input terminal of the second voltage follower is sequentially connected in series with a thirteenth resistor R13 and an eleventh resistor R11 and then serves as the input terminal of the fourth-stage amplifier circuit to be connected to the output terminal of the third-stage amplifier circuit. The intermediate terminal where the thirteenth resistor R13 and the positive input terminal of the second voltage follower are connected is grounded through a third capacitor C3, and the intermediate terminal where the thirteenth resistor R13 and the eleventh resistor are connected is grounded through a second capacitor C2. The output terminal of the second voltage follower serves as the output terminal of the fourth-stage amplifier circuit to output the amplified pulse signal.

[0048] To verify the effect of the pulse amplifier circuit based on the pressure sensor in this embodiment, this embodiment performs simulations on the signals output from the output terminal Vout1 of the second-stage amplifier circuit, the signals output from the output terminal Vout2 of the third-stage amplifier circuit, the signals output from the output terminal Vout3 of the fourth-stage amplifier circuit, the signal VG2 output from the negative output terminal of the FS19 pressure sensor, and the signal VG1 output from the positive output terminal of the FS19 pressure sensor. As Figure 3 can be seen, the amplitude waveforms of the original pulse signals represented by VG1 and VG2 are small. After being amplified by the output terminal Vout1 of the second-stage amplifier circuit, the output terminal Vout2 of the third-stage amplifier circuit, and the output terminal Vout3 of the fourth-stage amplifier circuit respectively, the amplitude waveforms become larger and are easier to collect. Moreover, compared with the original pulse signals of VG1 and VG2, the distortion rate of the obtained amplitude waveforms is low.

[0049] Embodiment 2

[0050] As Figure 4 shown, this embodiment is a pulse signal acquisition system, including the pulse amplifier circuit based on the pressure sensor in Embodiment 1, a signal acquisition unit for converting analog signals into digital signals, a signal processing unit, and a host computer.

[0051] The pulse amplification circuit based on a pressure sensor amplifies the original pulse signal obtained by the pressure sensor, obtains the amplified pulse signal and outputs it to the signal acquisition unit. After receiving the amplified pulse signal, the signal acquisition unit converts it into a digital signal. The output end of the signal acquisition unit outputs the digital signal to the signal processing unit, and the signal processing unit processes the digital signal and sends it to the host computer.

[0052] It should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pulse amplification circuit based on a pressure sensor, characterized in that, It includes a pressure sensor and an amplifier circuit based on the pressure sensor. The amplifier circuit based on the pressure sensor includes a first-stage amplifier circuit, a second-stage amplifier circuit, a third-stage amplifier circuit, a fourth-stage amplifier circuit, and a reference circuit; The pressure sensor uses a piezoresistive strain gauge, and its signal output terminal outputs an original pulse signal to the first-stage amplifier circuit. After receiving the original pulse signal at the signal input terminal of the first-stage amplifier circuit, a differential amplified signal is output. After receiving the differential amplified signal at the signal input terminal of the second-stage amplifier circuit, the common-mode signal is suppressed and a second amplified signal is output. After receiving the second amplified signal at the signal input terminal of the third-stage amplifier circuit, the DC is isolated and an AC signal is output through signal following. After receiving the AC signal, the fourth-stage amplifier circuit performs amplification and filtering to obtain an amplified pulse signal and outputs it; The reference signal output terminal of the reference circuit is used to output a reference voltage to the reference signal input terminal of the second-stage amplifier circuit.

2. The pulse amplification circuit based on a pressure sensor according to claim 1, wherein The first-stage amplifier circuit includes a first operational amplifier and a second operational amplifier; The positive input terminal of the first operational amplifier serves as the first input terminal of the first-stage amplifier circuit and is connected to the negative output terminal of the pressure sensor. The positive input terminal of the second operational amplifier serves as the second input terminal of the first-stage amplifier circuit and is connected to the positive output terminal of the pressure sensor. A fourth resistor is connected in series between the negative input terminal of the first operational amplifier and the negative input terminal of the second operational amplifier. At the same time, the negative input terminal of the first operational amplifier is also connected to its own output terminal through a third resistor, and the negative input terminal of the second operational amplifier is also connected to its own output terminal through a second resistor; the output terminal of the first operational amplifier is connected in series with a first resistor and serves as the first output terminal of the first-stage amplifier circuit; the output terminal of the second operational amplifier is connected in series with a radio frequency resistor and serves as the second output terminal of the first-stage amplifier circuit; The positive power supply terminal of the second operational amplifier is connected to the power supply, and the negative power supply terminal is grounded.

3. The pulse amplification circuit based on a pressure sensor according to claim 2, wherein The second-stage amplifier circuit includes a third operational amplifier; The negative input terminal of the third operational amplifier serves as the first input terminal of the second-stage amplifier circuit and is connected to the first output terminal of the first-stage amplifier circuit. The positive input terminal of the third operational amplifier serves as the second input terminal of the second-stage amplifier circuit and is connected to the second output terminal of the first-stage amplifier circuit. The output terminal of the third operational amplifier serves as the output terminal of the second-stage amplifier circuit and is connected to the input terminal of the third-stage amplifier circuit; The positive input terminal of the third operational amplifier is connected to the reference signal output terminal of the reference circuit through a fifth resistor in series, and the negative input terminal is connected to its own output terminal through a sixth resistor in series; The positive power supply terminal of the third operational amplifier is connected to the power supply, and the negative power supply terminal is grounded.

4. The pulse amplification circuit based on a pressure sensor according to claim 3, wherein The third-stage amplifier circuit includes a first voltage follower composed of a fourth operational amplifier; The positive input terminal of the first voltage follower is connected in series with a tenth resistor and a first capacitor in sequence and then serves as the input terminal of the third-stage amplifier circuit to be connected to the output terminal of the second-stage amplifier circuit. The middle node of the series circuit of the tenth resistor and the first capacitor is grounded through a twelfth resistor; the output terminal of the first voltage follower serves as the output terminal of the third-stage amplifier circuit; the positive power supply terminal of the first voltage follower is connected to the power supply, and the negative power supply terminal is grounded.

5. The pulse amplification circuit based on a pressure sensor according to claim 4, wherein The fourth-stage amplifier circuit includes a second voltage follower composed of a fifth operational amplifier; The positive input terminal of the second voltage follower is connected in series with a thirteenth resistor and an eleventh resistor in sequence and then serves as the input terminal of the fourth-stage amplifier circuit to be connected to the output terminal of the third-stage amplifier circuit. The middle node connected to the positive input terminal of the thirteenth resistor and the second voltage follower is grounded through a third capacitor, and the middle terminal connected to the thirteenth resistor and the eleventh resistor is grounded through a second capacitor; the output terminal of the second voltage follower serves as the output terminal of the fourth-stage amplifier circuit to output the amplified pulse signal.

6. The pulse amplification circuit based on a pressure sensor according to claim 5, characterized in that The reference circuit includes a sixth operational amplifier; The positive input terminal of the sixth operational amplifier is connected to an external power supply after being connected in series with a seventh resistor, and is also grounded through a parallel circuit of an eighth resistor and a ninth resistor connected in series; the output terminal of the sixth operational amplifier serves as the reference signal output terminal of the reference circuit and is connected to the reference signal input terminal of the second-stage amplifier circuit.

7. The pulse amplification circuit based on a pressure sensor according to claim 1, wherein, The pressure sensor is an FS19 pressure sensor.

8. A pulse signal acquisition system, characterized in that, It includes a pulse amplifier circuit based on a pressure sensor according to any one of claims 1 to 7, a signal acquisition unit for converting an analog signal into a digital signal, a signal processing unit, and a host computer; The pulse amplifier circuit based on the pressure sensor amplifies the original pulse signal obtained by the pressure sensor, obtains the amplified pulse signal and outputs it to the signal acquisition unit. After receiving the amplified pulse signal, the signal acquisition unit converts it into a digital signal. The output terminal of the signal acquisition unit outputs the digital signal to the signal processing unit, and the signal processing unit processes the digital signal and then sends it to the host computer.

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