A respiratory measurement system

Abstract

This utility model discloses a respiratory measurement system, including a lower-level computer and a higher-level computer communicating with it. The lower-level computer includes a data acquisition module and a data processing module connected in sequence. The data acquisition module includes a carrier circuit and a detection and demodulation circuit connected in sequence. The data processing module includes a microcontroller and a communication module connected in sequence. The input terminal of the microcontroller is connected to the output terminal of the detection and demodulation circuit, and the output terminal of the microcontroller is connected to the communication module. The communication module communicates with the higher-level computer. The carrier circuit includes a Wien bridge operational amplifier following a high-frequency oscillation circuit, a bandpass filter circuit, an inverting gain and second-order Bessel filter circuit, and a parallel signal correction circuit connected in sequence. Through communication between the lower-level computer and the higher-level computer, the lower-level computer integrates multiple circuits to acquire respiratory signals and transmits them to the higher-level computer for display, solving the problems of large sensor size, limited acquisition accuracy, and susceptibility to environmental influences.

Description

Technical Field

[0001] This utility model belongs to the field of circuit design and signal processing, and in particular relates to a respiratory measurement system. Background Technology

[0002] The statements in this section are merely background information relating to this disclosure and do not necessarily constitute prior art.

[0003] With the increasing health awareness of the public, respiratory health monitoring has gradually become an important part of health management.

[0004] Existing respiratory monitoring technologies mainly rely on traditional measurement devices, such as respiratory flow sensors, air pressure sensors, and temperature sensors. These devices typically detect respiratory signals by monitoring changes in airflow, gas pressure, or temperature. However, these traditional methods have certain limitations, such as large sensor size, limited acquisition accuracy, and some sensors being susceptible to external environmental influences, leading to unstable measurements. Utility Model Content

[0005] To address the technical problems existing in the prior art, this utility model provides a respiratory measurement system. Through communication between the lower-level computer and the upper-level computer, the lower-level computer integrates multiple circuits to collect and process respiratory signals, and transmits them to the upper-level computer for display, thus solving the problems of large sensor size, limited acquisition accuracy, and susceptibility to environmental influences.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] This utility model provides a respiratory measurement system, including a lower-level computer and a higher-level computer communicating with it. The lower-level computer includes a data acquisition module and a data processing module connected in sequence. The data acquisition module includes a carrier circuit and a detection and demodulation circuit connected in sequence. The data processing module includes a microcontroller and a communication module connected in sequence. The input terminal of the microcontroller is connected to the output terminal of the detection and demodulation circuit, and the output terminal of the microcontroller is connected to the communication module. The communication module communicates with the higher-level computer.

[0008] The carrier circuit includes a Wien bridge operational amplifier following a high-frequency oscillation circuit, a bandpass filter circuit, an inverting gain and second-order Bessel filter circuit, and a parallel signal correction circuit, all connected in sequence.

[0009] In a further technical solution, the Wien bridge operational amplifier following high-frequency oscillation circuit includes a first operational amplifier, the second pin of which is connected to the positive terminal of the first diode and the first end of the third resistor respectively; the third pin of the first operational amplifier is connected to the first end of the first capacitor, the second end of the first capacitor is connected to the first end of the fourth resistor, and the second end of the fourth resistor is connected to the sixth pin of the first operational amplifier, the negative terminal of the first diode, and the second end of the third resistor respectively.

[0010] In a further technical solution, the inverting gain and second-order Bessel filter circuit includes a fourth operational amplifier and a fifth operational amplifier. The second pin of the fourth operational amplifier is connected to the second end of the eleventh resistor, the first end of the twelfth capacitor, and the first end of the twelfth resistor, respectively. The second end of the twelfth resistor is connected to the second end of the twelfth capacitor and then connected to the first pin of the fourth operational amplifier. The first pin of the fourth operational amplifier is connected to the input terminal of the signal correction circuit. The first pin of the fourth operational amplifier is also connected to the sixth pin of the fifth operational amplifier.

[0011] In a further technical solution, the signal correction circuit includes a seventh operational amplifier. The positive input terminal of the seventh operational amplifier is connected to the second terminal of the sixteenth capacitor and the second terminal of the nineteenth resistor, respectively. The first terminal of the sixteenth capacitor is connected to the second terminal of the fifteenth capacitor and the first terminal of the twentieth resistor, respectively. The first terminal of the nineteenth resistor is connected to the second terminal of the eighteenth resistor and the first terminal of the seventeenth capacitor, respectively. The first terminal of the eighteenth resistor is connected to the first terminal of the fifteenth capacitor and then connected to the input terminal of the signal correction circuit.

[0012] In a further technical solution, the data acquisition module also includes a first filter circuit and an instrumentation amplifier circuit connected in sequence. The input terminal of the first filter circuit is connected to the output terminal of the carrier circuit, and the output terminal of the instrumentation amplifier circuit is connected to the input terminal of the detection and demodulation circuit.

[0013] In a further technical solution, the data acquisition module also includes a baseline adjustment circuit and a second filtering circuit connected in sequence. The input terminal of the baseline adjustment circuit is connected to the output terminal of the detection and demodulation circuit, and the output terminal of the second filtering circuit is connected to the input terminal of the microcontroller.

[0014] In a further technical solution, the data acquisition module also includes a lead-off circuit, the output of which is connected to the GPIO interface of the microcontroller.

[0015] In a further technical solution, the communication module is a serial communication module.

[0016] In a further technical solution, the data processing module also includes a power management circuit, which is bidirectionally connected to the communication module.

[0017] In a further technical solution, the host computer is a Qt host computer, and the Qt host computer is connected to the output terminal of the microcontroller.

[0018] The beneficial effects of this utility model are:

[0019] This invention employs a high-precision data acquisition module. By utilizing high-precision instrumentation amplification circuits and finely adjusted baseline adjustment circuits, it effectively suppresses environmental noise and common-mode interference, significantly improving the accuracy of respiratory signals. Simultaneously, the use of first and second filter circuits further reduces external interference, ensuring system stability and high measurement accuracy under various environments.

[0020] This invention features an innovative carrier circuit design that enables the application of a carrier signal to the human chest via electrodes, modulating the respiratory signal onto the carrier signal and achieving stable extraction and transmission of physiological signals.

[0021] This invention employs a lead detachment detection circuit, a baseline adjustment circuit, and adaptive filtering technology to ensure the stability of the system during use. In particular, the design of the baseline adjustment circuit can adjust the signal baseline according to the physiological characteristics of different users, thereby improving the system's adaptability and compatibility and effectively avoiding measurement errors under different human conditions.

[0022] This invention integrates multiple modules into a lower-level machine, resulting in a smaller size, lower cost compared to traditional oscilloscopes, and easier portability. It also reduces complex operations, greatly improving user convenience and comfort. Attached Figure Description

[0023] The accompanying drawings are provided to further understand the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.

[0024] Figure 1 This is a schematic diagram of the respiratory measurement system according to an embodiment of the present invention;

[0025] Figure 2 This is a block diagram of the respiratory measurement system according to an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the carrier circuit module according to an embodiment of the present invention;

[0027] Figure 4 This is a circuit diagram of the Wien bridge operational amplifier following the high-frequency oscillation in the carrier circuit of this utility model embodiment;

[0028] Figure 5 This is a diagram of the bandpass filter circuit in the carrier circuit of this utility model embodiment;

[0029] Figure 6 This is a diagram of the inverting gain and second-order Bessel filter circuit in the carrier circuit of this utility model embodiment;

[0030] Figure 7 This is a circuit diagram of the signal correction circuit in the carrier circuit of this utility model embodiment;

[0031] Figure 8 This is a diagram of the host computer interface display module according to an embodiment of the present utility model. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 1 , Figure 2 As shown in the figure, this utility model embodiment provides a respiratory measurement system, which includes a lower-level computer and a higher-level computer communicating with it. The lower-level computer includes a data acquisition module and a data processing module connected in sequence. The data acquisition module includes a carrier circuit and a detection and demodulation circuit connected in sequence. The data processing module includes a microcontroller and a communication module connected in sequence. The input terminal of the microcontroller is connected to the output terminal of the detection and demodulation circuit, and the output terminal of the microcontroller is connected to the communication module. The communication module communicates with the higher-level computer.

[0034] In this embodiment, the data acquisition module (also referred to as the data acquisition circuit) is used to acquire the user's respiratory signal. The input terminal of the data acquisition circuit is connected to the signal source under test, and the output terminal of the data acquisition circuit is connected to the input terminal of the microcontroller. The data acquisition module acquires the voltage signal of the signal source under test and sends the voltage signal reflecting the impedance change to the ADC module of the microcontroller.

[0035] The process of a respiratory measurement system measuring respiratory signals is as follows: Two electrodes are connected to the surface of the human body, and the chest cavity is treated as a homogeneous medium with uniform impedance distribution. Based on the variation in impedance, the system monitors human respiration. As the impedance changes periodically during respiration, approximating the periodic change in resistance of a potentiometer, the voltage amplitude between the electrodes changes accordingly. Therefore, the measured voltage signal reflects the impedance change.

[0036] In this embodiment, the carrier circuit is used to carry and transmit the weak respiratory signal (i.e., the acquired voltage signal). The carrier circuit is used to modulate and transmit the respiratory signal in respiratory signal measurement. The respiratory signal often needs to be modulated onto a high-frequency carrier to facilitate transmission and avoid interference from low-frequency signals.

[0037] like Figure 3As shown, the carrier circuit includes a Wien bridge operational amplifier following a high-frequency oscillation circuit, a bandpass filter circuit, an inverting gain and second-order Bessel filter circuit, and a parallel signal correction circuit, all connected in sequence.

[0038] like Figure 4 As shown, the Wien bridge op-amp follower high-frequency oscillation circuit includes a first operational amplifier U1. The second pin of the first operational amplifier U1 is connected to the second terminal of the second resistor R2, the positive terminal of the first diode D1, and the first terminal of the third resistor R3, respectively. The first terminal of the second resistor R2 is grounded. The third pin of the first operational amplifier U1 is connected to the second terminal of the first resistor R1, the second terminal of the second capacitor C2, and the first terminal of the first capacitor C1, respectively. The first terminal of the first resistor R1 and the first terminal of the second capacitor C2 are connected and then grounded. The second terminal of the first capacitor C1 is connected to the first terminal of the fourth resistor R4. The second terminal of the fourth resistor R4 is connected to the first operational amplifier U1. The sixth pin of the first operational amplifier U1 is connected to the cathode of the first diode D1 and the second terminal of the third resistor R3; the fourth pin of the first operational amplifier U1 is connected to the first terminal of the fourth capacitor C4, the first terminal of the sixth capacitor C6, and the power supply terminal VDD (-5V), respectively, and the second terminals of the fourth capacitor C4 and the sixth capacitor C6 are grounded; the seventh pin of the first operational amplifier U1 is connected to the first terminal of the third capacitor C3, the first terminal of the fifth capacitor C5, and the power supply terminal VCC (+5V), respectively, and the second terminals of the third capacitor C3 and the fifth capacitor C5 are grounded; the sixth pin of the first operational amplifier U1 is also connected to the first terminal of the sixth resistor R6 in the bandpass filter circuit.

[0039] In the Wien bridge op-amp following high-frequency oscillation circuit, the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 are used to set the gain of the operational amplifier; the first capacitor C1 and the second capacitor C2 are used to determine the oscillation frequency of the circuit; the third capacitor C3 and the fourth capacitor C4 are used to filter out high-frequency noise; the fifth capacitor C5 and the sixth capacitor C6 are used to smooth the power supply voltage; the first operational amplifier U1 is used to maintain continuous oscillation; and the first diode D1 is used to stabilize the oscillation amplitude and prevent output distortion.

[0040] like Figure 5 As shown, the bandpass filter circuit includes a second operational amplifier U2 and a third operational amplifier U3. The thirteenth pin of the second operational amplifier U2 is connected to the second terminal of the sixth resistor R6, the first terminal of the seventh resistor R7, and the first terminal of the seventh capacitor C7. The first terminal of the sixth resistor R6 is connected to the sixth pin of the first operational amplifier U1. The second terminal of the seventh capacitor C7 and the second terminal of the seventh resistor R7 are connected, and then connected to the fourteenth pin of the second operational amplifier U2. The fourteenth pin of the second operational amplifier U2 is connected to the first terminal of the eighth resistor R8. The twelfth pin of the second operational amplifier U2 is grounded.

[0041] The tenth pin of the third operational amplifier U3 is connected to the first terminal of the ninth capacitor C9 and the second terminal of the tenth resistor R10. The second terminal of the ninth capacitor C9 is grounded. The first terminal of the tenth resistor R10 is connected to the second terminal of the ninth resistor R9 and the second terminal of the tenth capacitor C10. The first terminal of the ninth resistor R9 is connected to the second terminal of the eighth resistor R8 and the first terminal of the eighth capacitor C8. The second terminal of the eighth capacitor C8 is grounded. The first terminal of the tenth capacitor C10 is connected to the ninth pin and the eighth pin of the third operational amplifier U3. The eighth pin of the third operational amplifier U3 is connected to the second pin of the fourth operational amplifier U4A.

[0042] In the bandpass filter circuit, the second operational amplifier U2 and the third operational amplifier U3 are used to implement filtering. The sixth resistor R6, the seventh resistor R7, the ninth resistor R9, the eighth resistor R8, and the tenth resistor R10 are used to set the passband frequency. The seventh capacitor C7, the eighth capacitor C8, the ninth capacitor C9, and the tenth capacitor C10 are used to set the passband frequency.

[0043] like Figure 6 As shown, the inverting gain and second-order Bessel filter circuit includes a fourth operational amplifier U4A and a fifth operational amplifier U5B. The second pin of the fourth operational amplifier U4A is connected to the second terminal of the eleventh resistor R11, the second terminal of the eleventh capacitor C11, the first terminal of the twelfth capacitor C12, and the first terminal of the twelfth resistor R2, respectively. The first terminal of the eleventh resistor R11 is connected to the eighth pin of the third operational amplifier U3. The first terminal of the eleventh capacitor C11 is grounded. The second terminal of the twelfth resistor R12 is connected to the second terminal of the twelfth capacitor C12 and then connected to the first pin of the fourth operational amplifier U4A. The first pin of the fourth operational amplifier U4A is connected to the input terminal of the signal correction circuit. The third pin of the fourth operational amplifier U4A is grounded, the fourth pin is connected to the power supply terminal VDD, and the eighth pin is connected to the power supply terminal VCC. The first pin of the fourth operational amplifier U4A is also connected to the first terminal of the thirteenth resistor R13.

[0044] The sixth pin of the fifth operational amplifier U5B is connected to the second terminal of the thirteenth resistor R13, the second terminal of the thirteenth capacitor C13, the first terminal of the fourteenth resistor R14, and the first terminal of the fourteenth capacitor C14. The first terminal of the thirteenth capacitor C13 is grounded. The second terminal of the fourteenth resistor R14 is connected to the second terminal of the fourteenth capacitor C14 and then connected to the seventh pin of the fifth operational amplifier U5B. The seventh pin of the fifth operational amplifier U5B is connected to the input terminal of the signal correction circuit. The fifth pin of the fifth operational amplifier U5B is grounded.

[0045] In the inverting gain and second-order Bessel filter circuit, the eleventh resistor R11, the twelfth resistor R12, the thirteenth resistor R13, and the fourteenth resistor R14 are used to set the circuit gain, frequency response, and filter cutoff frequency. The eleventh capacitor C11 and the twelfth capacitor C12 are used for filtering, while the thirteenth capacitor C13 and the fourteenth capacitor C14 are used to filter high-frequency noise and limit signal bandwidth. The fourth operational amplifier U4A is used for inverting gain and preliminary filtering, and the fifth operational amplifier U5B is used to complete the second-order Bessel filter, ensuring flat group delay within the passband.

[0046] like Figure 7 As shown, the signal correction circuit includes a seventh operational amplifier U7 and an eighth operational amplifier U8. The positive input terminal IN+ of the seventh operational amplifier U7 is connected to the second terminal of the sixteenth capacitor C16 and the second terminal of the nineteenth resistor R19. The first terminal of the sixteenth capacitor C16 is connected to the second terminal of the fifteenth capacitor C15 and the first terminal of the twentieth resistor R20. The second terminal of the twentieth resistor R20 is connected to the second terminal of the seventeenth capacitor C17 and the ground terminal. The first terminal of the nineteenth resistor R19 is connected to the second terminal of the eighteenth resistor R18 and the first terminal of the seventeenth capacitor C17. The second terminal of the seventeenth capacitor C17 is grounded. The first terminal of the eighteenth resistor R18 is connected to the first terminal of the fifteenth capacitor C15 and then connected to the input terminal of the signal correction circuit. The input terminal of the signal correction circuit is also connected to... The second terminal of the sixteenth resistor R16 and the first terminal of the seventeenth resistor R17 are connected together. The second terminal of the seventeenth resistor R17 is grounded. The first terminal of the sixteenth resistor R16 is connected to the third pin of the voltage regulator U6 (such as TL431), the second pin of the voltage regulator U6, and the second terminal of the fifteenth resistor R15. The first terminal of the fifteenth resistor R15 is connected to the power supply terminal VSS (+3.3V). The first pin of the voltage regulator U6 is grounded. The negative input terminal IN- of the seventh operational amplifier U7 is connected to the output terminal of the signal correction circuit and the first terminal of the twenty-first resistor R21. The output terminal OUT of the seventh operational amplifier U7 is connected to the output terminal of the signal correction circuit. The second terminal of the twenty-first resistor R21 is connected to the first terminal of the twenty-second resistor R22. The second terminal of the twenty-second resistor R22 is grounded.

[0047] The positive input terminal IN+ of the eighth operational amplifier U8 is grounded, and the negative input terminal IN- is connected to its output terminal OUT, the second end of the twentieth resistor R20, and the ground terminal, respectively.

[0048] In the signal correction circuit, resistors R15 (15th), R16 (16th), and R17 (17th) are used to generate a stable reference voltage; resistors R18 (18th), R19 (19th), and R20 (20th) form a double-T network to suppress 50Hz power frequency interference; resistors R21 (21st) and R22 (22nd) are used to adjust the operational amplifier gain; capacitors C15 (15th) and C16 (16th) are used to block DC components; capacitor C17 (17th) is used to filter out high-frequency interference; voltage regulator U6 is used as the reference voltage; operational amplifier U7 (7th) is used to amplify the notch filter signal; and operational amplifier U8 (8th) is used as a voltage follower to maintain stability.

[0049] The operational amplifier generated by U1 maintains stable oscillation by following the high-frequency signal, and the amplitude is limited by diode D1. Bandpass filters U2 and U3 select the frequency band of the carrier signal, filter out out-of-band noise, and improve the carrier signal. The carrier signal is then amplified by U4A and U5B inverting phase, and the Bessel characteristic is used to achieve linear phase delay to suppress high-frequency noise. The voltage baseline is adjusted by U6, and the signal is amplified and corrected by U7 in phase. The reference level is stabilized by the voltage follower U8, so that the carrier signal is applied to the human chest through the electrodes, and the respiratory signal is modulated onto the carrier signal, realizing the stable extraction and transmission of physiological signals.

[0050] In this embodiment, the detection and demodulation circuit is used to demodulate the breathing signal on the high-frequency carrier wave to obtain the breathing signal. In some embodiments, the detection and demodulation circuit may employ a precision full-wave rectifier circuit.

[0051] In this embodiment, the data acquisition module further includes a first filtering circuit, an instrumentation amplification circuit, a baseline adjustment circuit, a second filtering circuit, and a lead-drop circuit. The input terminal of the first filtering circuit is connected to the output terminal of the carrier circuit, the output terminal of the first filtering circuit is connected to the input terminal of the instrumentation amplification circuit, the output terminal of the instrumentation amplification circuit is connected to the input terminal of the detection and demodulation circuit, the output terminal of the detection and demodulation circuit is connected to the input terminal of the baseline adjustment circuit, the output terminal of the baseline adjustment circuit is connected to the input terminal of the second filtering circuit, and the output terminal of the second filtering circuit is connected to the ADC module of the microcontroller MCN to realize the transmission of respiratory signals.

[0052] The first and second filter circuits are used to filter out interference signals and avoid signal distortion; the instrumentation amplifier circuit is used to increase the input impedance and suppress common-mode signals; the baseline adjustment circuit is used to keep the respiratory signal in the center position, adapting to different human baselines and making the respiratory measurement system more compatible.

[0053] In some implementations, the first filter circuit can be constructed using an RC network to set the cutoff frequency and signal bandwidth; the instrumentation amplifier circuit can use a classic three-op-amp circuit with high input impedance and high common-mode rejection ratio; the baseline adjustment circuit can be implemented using two op-amps; and the second filter circuit can be constructed using an RC network to set the cutoff frequency and signal bandwidth.

[0054] The output of the lead detachment circuit is connected to the GPIO interface of the microcontroller to determine whether the lead connected to the human body has detached. In some implementations, a high-resistance resistor (e.g., 30MΩ) is connected to the lead input, and the voltage is detected by voltage division to see if it exceeds a threshold.

[0055] It should be noted that the first filter circuit, the instrumentation amplifier circuit, the detector demodulation circuit, the baseline adjustment circuit, the second filter circuit, and the lead disconnection circuit are all implemented using existing circuits, and will not be described in detail here.

[0056] In this embodiment, the microcontroller (MCU) is used to control the data acquisition module's data acquisition process, process the data, and transmit the processed data to the host computer.

[0057] The microcontroller (MCU) is implemented using an STM32 series microcontroller, such as the STM32F103RCT6. It has a built-in ADC module that samples the analog signals transmitted from the data acquisition module, converts them into digital signals, and processes them. The converted digital signals are then transferred to the microcontroller's data register via DMA or interrupts for further data processing.

[0058] Furthermore, the microcontroller's ADC module has at least 12 analog input channels. The STM32F103RCT6's ADC module supports up to 16 input channels, the exact number depending on the configuration and channel selection; it also supports multiple sampling modes, including single-conversion and continuous-conversion modes; and the voltage acquisition range of the ADC can be changed by adjusting the external reference voltage. The STM32F103RCT6 has a variety of general-purpose input / output (GPIO) interfaces, offering high performance and rich interfaces for external connectivity.

[0059] The microprocessor has a digital I / O port (the I / O port of the ADC module). The digital I / O port receives the data collected by the data acquisition module and outputs it to the serial communication module.

[0060] In this embodiment, the communication module is a serial communication module, which includes a TYPE-C interface and a USB to serial port device. It can be connected to the power module through the TYPE-C interface for power supply and communication.

[0061] The data processing module communicates with the host computer via a communication module. Specifically, the microcontroller of the data processing module connects to the host computer via a serial communication module to establish communication. The slave computer acquires respiratory signals and lead status and calculates respiratory rate through the data acquisition module. After processing by the data processing module, the data is sent to the host computer, which receives and displays the data.

[0062] In this embodiment, the data processing module further includes a power management circuit, which is bidirectionally connected to the communication module, and the communication module is bidirectionally connected to the microcontroller. The power management circuit is connected to the power supply to provide power to the microcontroller.

[0063] In some implementations, the power management circuit may be implemented using a Type-C 5V and a 5V to 3.3V AMS1117-3.3 chip, which is only an example and not a specific limitation.

[0064] In this embodiment, the host computer includes an interface display module, which is implemented using an existing Qt host computer. The Qt host computer sends instructions to the microcontroller via a serial port and receives data transmitted by the microcontroller, performing real-time data processing and display.

[0065] like Figure 8 As shown, the interface display module displays the respiratory signal waveform, the calculated respiratory rate, and the serial port number selection box. This module provides a graphical user interface that clearly and intuitively displays various data. The interface is easy to operate and more intuitive and simpler than traditional host computer display interfaces, capable of acquiring and displaying different signals. Utilizing Qt in conjunction with host and slave computers for data acquisition and display ensures stable system operation.

[0066] Detailed explanation of working principle:

[0067] By connecting two electrodes to the human body surface, during respiration, the data acquisition module collects a weak voltage signal (respiratory signal) reflecting impedance changes. This respiratory signal is modulated onto a high-frequency carrier wave via a carrier circuit. During transmission, a first filter circuit suppresses low-frequency interference. Then, a detection and demodulation circuit demodulates the modulated high-frequency signal to restore the original respiratory signal. Subsequently, the respiratory signal passes through a baseline adjustment circuit and a second filter circuit to further filter out interference, ensuring signal purity. The microcontroller samples the conditioned analog signal and converts it into a digital signal via an ADC module. The digital signal is then processed, such as calculating the respiratory rate. The processed data is transmitted to a host computer via a communication module, where the host computer displays the respiratory signal waveform, respiratory rate, etc., in real time.

[0068] Although the specific embodiments of the present utility model have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present utility model. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solution of the present utility model are still within the scope of protection of the present utility model.

Claims

1. A respiratory measurement system, characterized by: The system includes a lower-level machine and a higher-level machine that communicates with it. The lower-level machine includes a data acquisition module and a data processing module connected in sequence. The data acquisition module includes a carrier circuit and a detection and demodulation circuit connected in sequence. The data processing module includes a microcontroller and a communication module connected in sequence. The input terminal of the microcontroller is connected to the output terminal of the detection and demodulation circuit, and the output terminal of the microcontroller is connected to the communication module. The communication module communicates with the higher-level machine. The carrier circuit includes a Wien bridge operational amplifier following a high-frequency oscillation circuit, a bandpass filter circuit, an inverting gain and second-order Bessel filter circuit, and a parallel signal correction circuit, all connected in sequence.

2. A respiratory measurement system as claimed in claim 1, characterized in that: The Wien bridge operational amplifier following high-frequency oscillation circuit includes a first operational amplifier, the second pin of which is connected to the positive terminal of a first diode and the first terminal of a third resistor, respectively; the third pin of the first operational amplifier is connected to the first terminal of a first capacitor, the second terminal of the first capacitor is connected to the first terminal of a fourth resistor, and the second terminal of the fourth resistor is connected to the sixth pin of the first operational amplifier, the negative terminal of the first diode, and the second terminal of the third resistor, respectively.

3. A respiratory measurement system as claimed in claim 1, characterized in that: The inverting gain and second-order Bessel filter circuit includes a fourth operational amplifier and a fifth operational amplifier. The second pin of the fourth operational amplifier is connected to the second end of the eleventh resistor, the first end of the twelfth capacitor, and the first end of the twelfth resistor, respectively. The second end of the twelfth resistor is connected to the second end of the twelfth capacitor and then connected to the first pin of the fourth operational amplifier. The first pin of the fourth operational amplifier is connected to the input terminal of the signal correction circuit. The first pin of the fourth operational amplifier is also connected to the sixth pin of the fifth operational amplifier.

4. A respiratory measurement system as claimed in claim 1, characterized in that: The signal correction circuit includes a seventh operational amplifier. The positive input terminal of the seventh operational amplifier is connected to the second terminal of the sixteenth capacitor and the second terminal of the nineteenth resistor. The first terminal of the sixteenth capacitor is connected to the second terminal of the fifteenth capacitor and the first terminal of the twentieth resistor. The first terminal of the nineteenth resistor is connected to the second terminal of the eighteenth resistor and the first terminal of the seventeenth capacitor. The first terminal of the eighteenth resistor is connected to the first terminal of the fifteenth capacitor and then connected to the input terminal of the signal correction circuit.

5. A respiratory measurement system as claimed in claim 1, characterized in that: The data acquisition module further includes a first filter circuit and an instrumentation amplifier circuit connected in sequence. The input terminal of the first filter circuit is connected to the output terminal of the carrier circuit, and the output terminal of the instrumentation amplifier circuit is connected to the input terminal of the detection and demodulation circuit.

6. A respiratory measurement system as claimed in claim 1, characterized in that: The data acquisition module also includes a baseline adjustment circuit and a second filtering circuit connected in sequence. The input terminal of the baseline adjustment circuit is connected to the output terminal of the detection and demodulation circuit, and the output terminal of the second filtering circuit is connected to the input terminal of the microcontroller.

7. A respiratory measurement system as claimed in claim 1, characterized in that: The data acquisition module also includes a lead-off circuit, the output of which is connected to the GPIO interface of the microcontroller.

8. A respiratory measurement system as claimed in claim 1, characterized in that: The communication module is a serial communication module.

9. A respiratory measurement system as claimed in claim 1, characterized in that: The data processing module also includes a power management circuit, which is bidirectionally connected to the communication module.

10. A respiratory measurement system as claimed in claim 1, characterized in that: The host computer is a Qt host computer, which is connected to the output of the microcontroller.

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