阅读说明：本技术 心电基线漂移滤波装置、心电信号采样系统及采样方法 (Electrocardio baseline drift filtering device, electrocardio signal sampling system and electrocardio signal sampling method ) 是由 许冬回 孙华 冯天铭 徐文彬 于 2021-08-24 设计创作，主要内容包括：本申请涉及心电基线漂移滤波装置、心电信号采样系统及采样方法,其装置包括信号放大模块、控制模块、开关模块以及模拟积分器；开关模块,用于获取控制模块传输的滤波频率调节指令切换开关,以改变模拟积分器的截止频率；模拟积分器,用于根据截止频率,对经过信号放大模块放大的心电信号进行积分,并将积分结果反馈到信号放大模块,以使信号放大模块输出恒定直流电压的心电放大信号；信号放大模块,用于获取人体的心电信号进行放大并输出至模拟积分器,同时输出恒定直流电压的心电放大信号至控制模块；控制模块,用于对心电放大信号进行滤波采样,得到心电数字信号。本申请能够实现基线漂移滤波频率可调,提高基线漂移硬件滤波的可适用性和效果。(The application relates to an electrocardio baseline drift filtering device, an electrocardio signal sampling system and a sampling method, wherein the device comprises a signal amplification module, a control module, a switch module and an analog integrator; the switch module is used for acquiring a filtering frequency adjusting instruction transmitted by the control module to switch the switch so as to change the cut-off frequency of the analog integrator; the analog integrator is used for integrating the electrocardiosignals amplified by the signal amplification module according to the cut-off frequency and feeding back the integration result to the signal amplification module so as to enable the signal amplification module to output the electrocardio amplification signals with constant direct-current voltage; the signal amplification module is used for acquiring an electrocardiosignal of a human body, amplifying the electrocardiosignal and outputting the electrocardiosignal to the analog integrator, and meanwhile, outputting the electrocardiosignal with constant direct-current voltage to the control module; and the control module is used for filtering and sampling the electrocardio amplification signal to obtain an electrocardio digital signal. The method and the device can realize adjustable baseline wander filtering frequency and improve the applicability and the effect of baseline wander hardware filtering.)

1. The electrocardio baseline drift filtering device is characterized by comprising a signal amplification module, a control module, a switch module and an analog integrator; the signal amplification module is electrically connected with the control module, the switch module and the analog integrator are sequentially and electrically connected, and the analog integrator is electrically connected with the signal amplification module;

the control module is used for acquiring a filtering frequency adjusting instruction and transmitting the filtering frequency adjusting instruction to the switch module;

the switch module is used for switching a switch according to a filtering frequency adjusting instruction so as to change the cut-off frequency of the analog integrator;

the analog integrator is used for integrating the electrocardiosignal amplified by the signal amplification module according to the cut-off frequency and feeding back an integration result to the signal amplification module so as to enable the signal amplification module to output an electrocardio amplification signal with constant direct-current voltage;

the signal amplification module is used for acquiring an electrocardiosignal of a human body, amplifying the electrocardiosignal to output the electrocardiosignal to the analog integrator, and simultaneously outputting an electrocardiosignal with constant direct-current voltage to the control module;

the control module is further configured to perform low-pass filtering and AD sampling on the electrocardiograph amplification signal to obtain a filtered electrocardiograph digital signal.

2. The electrocardiograph baseline shift filtering apparatus according to claim 1, wherein the switch module comprises a power supply voltage conversion unit and a switch switching unit, the power supply voltage conversion unit is electrically connected to the control module, and the switch switching unit is electrically connected to the integrator;

the power supply voltage conversion unit is used for converting the single power supply control signal output by the control module into a double power supply control signal and transmitting the double power supply control signal to the switch switching unit;

the switch switching unit is used for controlling the working state of a switch according to a dual-power control signal so as to switch the key resistor of the analog integrator and change the cut-off frequency of the analog integrator.

3. The electrocardiographic baseline shift filter device according to claim 2, wherein the analog integrator comprises an operational amplifier U3A, a capacitor C271, a resistor R484 and a resistor R486;

the non-inverting input end of the operational amplifier U3A is grounded, the inverting input end is respectively connected with one end of a resistor R484 and one end of a resistor R486, the other end of the resistor R484 and the other end of the resistor R486 are both connected with the switch switching unit, and the capacitor C271 is connected between the inverting input end and the output end of the operational amplifier U3A in series; the other end of the resistor R484 is connected with the signal amplification module;

controlling the working state of a switch according to the switch switching unit, wherein when a resistor R484 and a resistor R486 of the analog integrator are simultaneously connected, the cut-off frequency of the analog integrator is a first cut-off frequency, and the cut-off frequency is 0.47-0.67 Hz; when the analog integrator is only connected with the resistor R484, the cut-off frequency of the analog integrator is the second cut-off frequency, and the size of the cut-off frequency is 0.04-0.05 Hz.

4. The electrocardio baseline wander filtering device of claim 2, wherein the switch switching unit adopts a single-pole single-throw analog switch; the power supply voltage conversion unit adopts a mos tube voltage conversion circuit;

the mos tube voltage conversion circuit comprises a mos tube Q1, a resistor R487, a resistor R488, a resistor R489, a resistor R490, a capacitor C274 and a capacitor C275;

the grid electrode of the mos tube Q1 is connected with one end of the resistor R487, and the other end of the resistor R487 is used as the input end of the mos tube voltage conversion circuit; one end of the resistor R488 is connected between the grid of the mos tube Q1 and the resistor R487, and the other end of the resistor R488 is grounded; the source electrode of the mos tube Q1 is connected with the positive voltage end of the power supply, and the drain electrode is connected with the negative voltage end of the power supply through a resistor R489; one end of the capacitor C274 is connected with the source electrode of the mos tube Q1, and the other end of the capacitor C is grounded; one end of the capacitor C275 is connected between the resistor R489 and the negative voltage end of the power supply, and the other end is grounded; one end of the resistor R490 is connected with the drain electrode of the mos tube Q1, and the other end of the resistor R is used as the output end of the mos tube voltage conversion circuit.

5. The electrocardio baseline wander filtering device according to any one of claims 1 to 3, further comprising a signal input module, wherein the signal input module is used for acquiring electrocardiosignals of a human body and transmitting the electrocardiosignals to the signal amplification module; the signal input module adopts a buffer circuit.

6. The electrocardio baseline wander filtering device according to any one of claims 1 to 3, wherein the signal amplifying module comprises a primary amplifying unit and a secondary amplifying unit, an output end of the primary amplifying unit is electrically connected with an input end of the secondary amplifying unit, and an output end of the secondary amplifying unit is electrically connected with an input end of the control module; the input end and the output end of the primary amplification unit are respectively and electrically connected with the analog integrator;

the primary amplification unit is used for amplifying the electrocardiosignals according to a preset first amplification factor, offsetting a direct current baseline drift part in the input electrocardiosignals according to an integration result by acquiring the integration result fed back by the analog integrator, outputting the electrocardiosignals with constant direct current voltage and transmitting the electrocardiosignals with constant direct current voltage to the secondary amplification unit;

the second-stage amplification unit is used for amplifying the electrocardiosignals amplified by the first-stage amplification unit according to a preset second amplification factor so as to output the electrocardio-amplified signals to the control module.

7. The electrocardio baseline wander filtering device of claim 6, wherein the primary amplifying unit adopts a differential amplifying mode, and the first amplification factor is 3 times or 6 times; the second-stage amplification unit adopts an operational amplification mode, and the second amplification factor is 100-200 times.

8. The electrocardiogram baseline shift filtering apparatus as recited in claim 1, wherein said control module comprises a low pass filtering unit and a main control unit; the low-pass filtering unit is electrically connected with the AD sampling end of the main control unit, the input end of the low-pass filtering unit is electrically connected with the output end of the signal amplification module, and the output end of the main control module is electrically connected with the input end of the switch module;

the low-pass filtering unit is used for carrying out low-pass filtering and denoising on the electrocardio amplification signal output by the signal amplification module and transmitting the electrocardio amplification signal subjected to low-pass filtering and denoising to the main control unit;

and the main control unit is used for carrying out AD sampling on the electrocardio amplified signal subjected to low-pass filtering and denoising so as to obtain a filtered electrocardio digital signal.

9. An electrocardiosignal sampling system, which is characterized by comprising a sensing module, an electrocardiosignal baseline shift filtering device as claimed in any one of claims 1 to 8 and/or a command input module; the sensing module is electrically connected with the electrocardio baseline drift filtering device, and/or the instruction input module is electrically connected with the electrocardio baseline drift filtering device; the sensing device adopts an acceleration sensor;

the sensing module is used for detecting human body movement information and transmitting the human body movement information to the electrocardio baseline drift filtering device;

the instruction input module is used for manually inputting a filtering frequency adjusting instruction;

the electrocardio baseline filtering device is used for triggering an internal filtering frequency adjusting instruction when the human body movement information exceeds a preset threshold value so as to switch the cut-off frequency of the corresponding analog integrator and realize baseline filtering of different frequencies;

and/or the electrocardio baseline filtering device is used for acquiring a filtering frequency adjusting instruction transmitted by the instruction input module so as to switch the cut-off frequency of the corresponding analog integrator to realize baseline filtering with different frequencies.

10. An electrocardiographic signal sampling method applied to the electrocardiographic signal sampling system according to claim 9, characterized in that the method comprises:

acquiring human body movement information, wherein the movement information comprises movement acceleration and duration;

judging whether the human body movement acceleration exceeds a preset acceleration threshold value or not and whether the duration time exceeds a preset time threshold value or not;

if so, triggering a first filtering frequency adjusting instruction to enable the electrocardio baseline filtering device to be switched to a first cut-off frequency to filter and sample electrocardio signal baseline noise to obtain a filtered electrocardio digital signal; wherein the first cutoff frequency is greater than the second cutoff frequency;

if not, triggering a second filtering frequency adjusting instruction to enable the electrocardio baseline filtering device to be switched to a second cut-off frequency to filter and sample electrocardio signal baseline noise to obtain a filtered electrocardio digital signal.

Technical Field

The application relates to the technical field of signal filtering, in particular to an electrocardio baseline drift filtering device, an electrocardio signal sampling system and a sampling method.

Background

At present, human electrocardio detection is commonly used in medical equipment, and the collected human electrocardio signals may have baseline drift. When the baseline drift filtering of the existing dynamic electrocardio equipment adopts hardware filtering, the filtering frequency is generally fixed, so that the defect exists, if the frequency is set to be too low, the electromyographic filtering has long adjusting time, namely the adjusting time for filtering the electromyographic signals from the electrocardiosignals is long. If the frequency is set to be higher, the dynamic electrocardiogram equipment cannot have the ST segment measuring function in the electrocardiogram, because the frequency of the ST segment can reach 0.05Hz at the lowest. Therefore, when baseline drift filtering is performed on the hardware based on the dynamic electrocardiograph equipment, the single filtering frequency cannot well meet the actual requirement.

Disclosure of Invention

In view of this, the present application provides an electrocardiographic baseline shift filtering device, an electrocardiographic signal sampling system, and a sampling method, so as to solve the technical problem that the filtering frequency of the baseline shift hardware of the conventional dynamic electrocardiography is not adjustable.

In order to solve the above problem, in a first aspect, the present application provides an electrocardiographic baseline shift filtering apparatus, which includes a signal amplification module, a control module, a switch module, and an analog integrator; the signal amplification module is electrically connected with the control module, the switch module and the analog integrator are sequentially and electrically connected, and the analog integrator is electrically connected with the signal amplification module;

the control module is used for acquiring a filtering frequency adjusting instruction and transmitting the filtering frequency adjusting instruction to the switch module;

the switch module is used for switching a switch according to a filtering frequency adjusting instruction so as to change the cut-off frequency of the analog integrator;

the analog integrator is used for integrating the electrocardiosignal amplified by the signal amplification module according to the cut-off frequency and feeding back an integration result to the signal amplification module so as to enable the signal amplification module to output an electrocardio amplification signal with constant direct-current voltage;

the signal amplification module is used for acquiring an electrocardiosignal of a human body, amplifying the electrocardiosignal to output the electrocardiosignal to the analog integrator, and simultaneously outputting an electrocardiosignal with constant direct-current voltage to the control module;

the control module is further configured to perform low-pass filtering and AD sampling on the electrocardiograph amplification signal to obtain a filtered electrocardiograph digital signal.

Optionally, the switch module includes a power supply voltage conversion unit and a switch switching unit, the power supply voltage conversion unit is electrically connected to the control module, and the switch switching unit is electrically connected to the integrator;

the power supply voltage conversion unit is used for converting the single power supply control signal output by the control module into a double power supply control signal and transmitting the double power supply control signal to the switch switching unit;

the switch switching unit is used for controlling the working state of a switch according to a dual-power control signal so as to switch the key resistor of the analog integrator and change the cut-off frequency of the analog integrator.

Optionally, the analog integrator includes an operational amplifier U3A, a capacitor C271, a resistor R484, and a resistor R486;

the non-inverting input end of the operational amplifier U3A is grounded, the inverting input end is respectively connected with one end of a resistor R484 and one end of a resistor R486, the other end of the resistor R484 and the other end of the resistor R486 are both connected with the switch switching unit, and the capacitor C271 is connected between the inverting input end and the output end of the operational amplifier U3A in series; the other end of the resistor R484 is connected with the signal amplification module;

controlling the working state of a switch according to the switch switching unit, wherein when a resistor R484 and a resistor R486 of the analog integrator are simultaneously connected, the cut-off frequency of the analog integrator is a first cut-off frequency, and the cut-off frequency is 0.47-0.67 Hz; when the analog integrator is only connected with the resistor R484, the cut-off frequency of the analog integrator is the second cut-off frequency, and the size of the cut-off frequency is 0.04-0.05 Hz.

Optionally, the switch switching unit adopts a single-pole single-throw analog switch; the power supply voltage conversion unit adopts a mos tube voltage conversion circuit;

the mos tube voltage conversion circuit comprises a mos tube Q1, a resistor R487, a resistor R488, a resistor R489, a resistor R490, a capacitor C274 and a capacitor C275;

the grid electrode of the mos tube Q1 is connected with one end of the resistor R487, and the other end of the resistor R487 is used as the input end of the mos tube voltage conversion circuit; one end of the resistor R488 is connected between the grid of the mos tube Q1 and the resistor R487, and the other end of the resistor R488 is grounded; the source electrode of the mos tube Q1 is connected with the positive voltage end of the power supply, and the drain electrode is connected with the negative voltage end of the power supply through a resistor R489; one end of the capacitor C274 is connected with the source electrode of the mos tube Q1, and the other end of the capacitor C is grounded; one end of the capacitor C275 is connected between the resistor R489 and the negative voltage end of the power supply, and the other end is grounded; one end of the resistor R490 is connected with the drain electrode of the mos tube Q1, and the other end of the resistor R is used as the output end of the mos tube voltage conversion circuit.

Optionally, the device further comprises a signal input module, wherein the signal input module is used for acquiring an electrocardiosignal of a human body and transmitting the electrocardiosignal to the signal amplification module; the signal input module adopts a buffer circuit.

Optionally, the signal amplification module includes a first-stage amplification unit and a second-stage amplification unit, an output end of the first-stage amplification unit is electrically connected with an input end of the second-stage amplification unit, and an output end of the second-stage amplification unit is electrically connected with an input end of the control module; the input end and the output end of the primary amplification unit are respectively and electrically connected with the analog integrator;

the primary amplification unit is used for amplifying the electrocardiosignals according to a preset first amplification factor, offsetting a direct current baseline drift part in the input electrocardiosignals according to an integration result by acquiring the integration result fed back by the analog integrator, outputting the electrocardiosignals with constant direct current voltage and transmitting the electrocardiosignals with constant direct current voltage to the secondary amplification unit;

the second-stage amplification unit is used for amplifying the electrocardiosignals amplified by the first-stage amplification unit according to a preset second amplification factor so as to output the electrocardio-amplified signals to the control module.

Optionally, the first-stage amplification unit adopts a differential amplification mode, and the first amplification factor is 3 times or 6 times; the second-stage amplification unit adopts an operational amplification mode, and the second amplification factor is 100-200 times.

Optionally, the control module includes a low-pass filtering unit and a main control unit; the low-pass filtering unit is electrically connected with the AD sampling end of the main control unit, the input end of the low-pass filtering unit is electrically connected with the output end of the signal amplification module, and the output end of the main control module is electrically connected with the input end of the switch module;

the low-pass filtering unit is used for carrying out low-pass filtering and denoising on the electrocardio amplification signal output by the signal amplification module and transmitting the electrocardio amplification signal subjected to low-pass filtering and denoising to the main control unit;

and the main control unit is used for carrying out AD sampling on the electrocardio amplified signal subjected to low-pass filtering and denoising so as to obtain a filtered electrocardio digital signal.

In a second aspect, the present application provides an electrocardiograph signal sampling system, which includes a sensing module, the electrocardiograph baseline drift filtering device, and/or an instruction input module; the sensing module is electrically connected with the electrocardio baseline drift filtering device, and/or the instruction input module is electrically connected with the electrocardio baseline drift filtering device; the sensing device adopts an acceleration sensor;

the sensing module is used for detecting human body movement information and transmitting the human body movement information to the electrocardio baseline drift filtering device;

the instruction input module is used for manually inputting a filtering frequency adjusting instruction;

the electrocardio baseline filtering device is used for triggering an internal filtering frequency adjusting instruction when the human body movement information exceeds a preset threshold value so as to switch the cut-off frequency of the corresponding analog integrator and realize baseline filtering of different frequencies;

and/or the electrocardio baseline filtering device is used for acquiring a filtering frequency adjusting instruction transmitted by the instruction input module so as to switch the cut-off frequency of the corresponding analog integrator to realize baseline filtering with different frequencies.

In a third aspect, the present application provides an electrocardiograph signal sampling method, applied to the electrocardiograph signal sampling system, the method including:

acquiring human body movement information, wherein the movement information comprises movement acceleration and duration;

judging whether the human body movement acceleration exceeds a preset acceleration threshold value or not and whether the duration time exceeds a preset time threshold value or not;

if so, triggering a first filtering frequency adjusting instruction to enable the electrocardio baseline filtering device to be switched to a first cut-off frequency to filter and sample electrocardio signal baseline noise to obtain a filtered electrocardio digital signal; wherein the first cutoff frequency is greater than the second cutoff frequency;

if not, triggering a second filtering frequency adjusting instruction to enable the electrocardio baseline filtering device to be switched to a second cut-off frequency to filter and sample electrocardio signal baseline noise to obtain a filtered electrocardio digital signal.

The beneficial effects of adopting the above embodiment are: acquiring and amplifying human electrocardiosignals through a signal amplification module; a filtering frequency adjusting instruction is obtained through a switch module to change the cut-off frequency of the analog integrator, so that the subsequent baseline filtering frequency is adjustable; the analog integrator integrates the electrocardiosignal amplified by the signal amplification module according to the cut-off frequency, and feeds back the integration result to the signal amplification module so that the signal amplification module outputs the electrocardio amplification signal with constant direct current voltage, so that the signal amplification module can keep the constant direct current output voltage even if the skin contact resistance changes in the electrocardio signal acquisition process, and the baseline drift interference is reduced; and filtering and sampling the electrocardio amplified signal through a control module to finally obtain an electrocardio digital signal convenient to analyze. The method and the device can realize adjustable baseline wander filtering frequency, and improve the applicability and filtering effect of baseline wander hardware filtering.

Drawings

Fig. 1 is a schematic block diagram of an embodiment of an electrocardiographic baseline shift filtering apparatus provided in the present application;

FIG. 2 is a circuit diagram of an embodiment of a buffer circuit provided herein;

FIG. 3 is a circuit diagram of an embodiment of a switching unit, an analog integrator, and a first stage amplifying unit provided in the present application;

FIG. 4 is a circuit diagram of an embodiment of a two-stage amplification unit provided in the present application;

fig. 5 is a circuit diagram of an embodiment of a power supply voltage conversion unit provided in the present application;

fig. 6 is a flowchart of a method according to an embodiment of the present application.

Detailed Description

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate preferred embodiments of the application and together with the description, serve to explain the principles of the application and not to limit the scope of the application.

At present, the electric signal of the electrocardio waveform of a human body acquired by dynamic electrocardio equipment through an electrode is generally 1mv peak value and contains rich harmonic waves. In order for this signal to be useful for analysis, a magnification factor of about 200 times or more is required. The electrocardio waveform of the human body is not single frequency, and the electrocardiosignal contains rich harmonic waves. If the electrocardiograph has the same gain for signals of different frequencies, the traced waveform will not be distorted, but the amplification capabilities of the amplifiers for signals of different frequencies are not necessarily the same. The hardware baseline filtering of the existing dynamic electrocardiograph equipment is generally a fixed filtering frequency, and when baseline drift filtering is carried out, a single filtering frequency cannot well respond to signals with different frequencies.

Referring to fig. 1, an embodiment of the present application provides an electrocardiographic baseline shift filtering apparatus, which includes a signal amplification module 101, a control module 102, a switch module 103, and an analog integrator 104; the signal amplification module is electrically connected with the control module, the switch module and the analog integrator are sequentially and electrically connected, and the analog integrator is electrically connected with the signal amplification module.

The control module 102 is used for acquiring a filtering frequency adjusting instruction and transmitting the filtering frequency adjusting instruction to the switch module; the switch module 103 is used for switching a switch according to the filtering frequency adjusting instruction so as to change the cut-off frequency of the analog integrator; the analog integrator 104 is used for integrating the electrocardiosignal amplified by the signal amplification module according to the cut-off frequency and feeding back an integration result to the signal amplification module so that the signal amplification module outputs an electrocardio amplification signal with constant direct-current voltage; the signal amplification module 101 is used for acquiring an electrocardiosignal of a human body, amplifying the electrocardiosignal to output the electrocardiosignal to the analog integrator, and simultaneously outputting an electrocardiosignal with constant direct-current voltage to the control module; the control module 102 is further configured to perform filtering and AD sampling on the electrocardiographic amplification signal to obtain a filtered electrocardiographic digital signal.

In the embodiment, the electrocardiosignals of the human body are obtained and amplified through the signal amplification module; a filtering frequency adjusting instruction is obtained through a switch module to change the cut-off frequency of the analog integrator, so that the subsequent baseline filtering frequency is adjustable; the analog integrator integrates the electrocardiosignal amplified by the signal amplification module according to the cut-off frequency, and feeds back the integration result to the signal amplification module so that the signal amplification module outputs the electrocardio amplification signal with constant direct current voltage, so that the signal amplification module can keep the constant direct current output voltage even if the skin contact resistance changes in the electrocardio signal acquisition process, and the baseline drift interference is reduced; and filtering and sampling the electrocardio amplified signal through a control module to finally obtain an electrocardio digital signal convenient to analyze. The method and the device can realize adjustable baseline wander filtering frequency, and improve the applicability and filtering effect of baseline wander hardware filtering.

In an embodiment, the electrocardio baseline drift filtering device further comprises a signal input module, wherein the signal input module is used for acquiring electrocardiosignals of a human body and transmitting the electrocardiosignals to the signal amplification module; the signal input module adopts a buffer circuit. In a specific application embodiment, as shown in the buffer circuit shown in fig. 2, only two electrodes are shown at the signal input end of the buffer circuit, and are used for detecting an electrocardiographic signal when contacting with the skin of a human body.

It should be noted that, because the amplification factor of the signal amplification module is relatively large, the signal at the filtering and sampling end of the control module is very sensitive to the change of the contact resistance between the electrode and the skin, which may cause baseline wander interference on the finally generated electrocardiogram, and even affect the sampling at the filtering and sampling end of the control module.

In one embodiment, the signal amplification module comprises a first-stage amplification unit and a second-stage amplification unit, wherein the output end of the first-stage amplification unit is electrically connected with the input end of the second-stage amplification unit, and the output end of the second-stage amplification unit is electrically connected with the input end of the control module; the input end and the output end of the first-stage amplification unit are respectively and electrically connected with the analog integrator.

The primary amplification unit is used for amplifying the electrocardiosignals according to a preset first amplification factor, offsetting a direct current baseline drift part in the input electrocardiosignals according to an integration result by acquiring the integration result fed back by the analog integrator, so as to output the electrocardiosignals with constant direct current voltage, and transmitting the electrocardiosignals with constant direct current voltage to the secondary amplification unit; and the second-stage amplification unit is used for amplifying the electrocardiosignals amplified by the first-stage amplification unit according to a preset second amplification factor so as to output the electrocardio-amplified signals to the control module.

In one embodiment, the first-stage amplification unit adopts a differential amplification mode, and the first amplification factor is 3 times or 6 times; the second-stage amplification unit adopts an operational amplification mode, and the second amplification factor is 100-200 times. In a specific embodiment, as shown in fig. 3, the primary amplification unit employs an instrumentation amplifier U2, which may be in the form of INA 317; the two-stage amplification unit may employ a low power op amp with a gain-bandwidth product greater than 1MHz, as shown in fig. 4. It should be noted that, in other embodiments, specific models of the first-stage amplification unit and the second-stage amplification unit may be determined according to actual situations, and are not limited herein.

It should be noted that the input end and the output end of the primary amplification unit are respectively electrically connected to the analog integrator, and as shown in fig. 3, the output end of the analog integrator is electrically connected to the 5 th port of the instrumentation amplifier U2, so that the analog integrator integrates the direct current component of the electrocardiographic signal amplified by the primary amplification unit, and then feeds back the integration result to the primary amplification unit, and cancels the direct current baseline drift portion in the input electrocardiographic signal according to the integration result, thereby solving the baseline drift problem. In addition, as shown in fig. 3, in the present embodiment, the primary amplification unit is connected to the secondary amplification unit through the 6 th port.

In one embodiment, the control module comprises a low-pass filtering unit and a main control unit; the low-pass filtering unit is electrically connected with the AD sampling end of the main control unit, the input end of the low-pass filtering unit is electrically connected with the output end of the signal amplification module, and the output end of the main control module is electrically connected with the input end of the switch module.

The low-pass filtering unit is used for carrying out low-pass filtering and denoising on the electrocardio amplification signals output by the signal amplification module and transmitting the electrocardio amplification signals subjected to low-pass filtering and denoising to the main control unit; and the main control unit is used for sampling the electrocardio amplified signal subjected to low-pass filtering and denoising so as to obtain a filtered electrocardio digital signal.

In this embodiment, the main control unit may adopt an MCU singlechip, which is provided with an AD sampling terminal; according to the embodiment, electrocardiosignals of a human body are collected through the electrodes, the signals enter a first-stage differential amplification mode after being buffered, then are subjected to a second-stage amplification mode, and finally are filtered and sent to the AD sampling end of the MCU singlechip. In addition, in the embodiment, the low-pass filtering unit adopts a filtering circuit with an operational amplifier structure; in other embodiments, the filtering may be implemented by using a capacitor or a resistor, which may be determined according to actual conditions.

In an embodiment, the switch module includes a supply voltage conversion unit and a switch switching unit, the supply voltage conversion unit is electrically connected to the control module, and the switch switching unit is electrically connected to the analog integrator, as shown in fig. 3.

The power supply voltage conversion unit is used for converting the single power supply control signal output by the control module into a double power supply control signal and transmitting the double power supply control signal to the switch switching unit; and the switch switching unit is used for controlling the working state of the switch according to the dual-power control signal so as to switch the key resistor of the analog integrator and change the cut-off frequency of the analog integrator.

In one embodiment, the switch switching unit employs a single-pole single-throw analog switch, such as the analog switch U5 in fig. 3; the power supply voltage conversion unit adopts a mos tube voltage conversion circuit.

Referring to fig. 5, the mos transistor voltage conversion circuit includes a mos transistor Q1, a resistor R487, a resistor R488, a resistor R489, a resistor R490, a capacitor C274, and a capacitor C275; the grid of the mos tube Q1 is connected with one end of the resistor R487, and the other end of the resistor R487 is used as the input end of the mos tube voltage conversion circuit; one end of the resistor R488 is connected between the grid of the mos tube Q1 and the resistor R487, and the other end of the resistor R488 is grounded; the source electrode of the mos tube Q1 is connected with the positive voltage end of the power supply, and the drain electrode is connected with the negative voltage end of the power supply through a resistor R489; one end of the capacitor C274 is connected with the source electrode of the mos tube Q1, and the other end of the capacitor C is grounded; one end of the capacitor C275 is connected between the resistor R489 and the negative voltage end of the power supply, and the other end is grounded; one end of the resistor R490 is connected with the drain electrode of the mos transistor Q1, and the other end of the resistor R serves as the output end of the mos transistor voltage conversion circuit.

It should be noted that, because the low level of the MCU singlechip output control level is 0V and the high level is 3.3V, and the operating voltage of the analog switch U5 is + -2.7V, it cannot be directly controlled. The mos tube voltage conversion circuit is simple and practical, a single power supply control signal is converted into a dual power supply control signal, and the mos tube voltage conversion circuit outputs-2.7V when the MCU singlechip outputs a high level; when the MCU single chip outputs a low level, the mos transistor voltage conversion circuit outputs +2.7V, thereby controlling the analog switch U5 to switch the enable pin, as shown in fig. 3 and 5, the output terminal base _ CON of the mos transistor voltage conversion circuit is connected to the 7 th port of the analog switch U5 of the switch switching unit, thereby implementing the switch switching control.

In one embodiment, referring to fig. 3, the analog integrator includes an operational amplifier U3A, a capacitor C271, a resistor R484, and a resistor R486; the non-inverting input end of the operational amplifier U3A is grounded, the inverting input end is connected with one end of a resistor R484 and one end of a resistor R486 respectively, the other end of the resistor R484 and the other end of the resistor R486 are both connected with a switch switching unit, and a capacitor C271 is connected between the inverting input end and the output end of the operational amplifier U3A in series; and the other end of the resistor R484 is connected with the signal amplification module. Controlling the working state of a switch according to the switch switching unit, wherein when a resistor R484 and a resistor R486 of the analog integrator are simultaneously connected, the cut-off frequency of the analog integrator is a first cut-off frequency, and the cut-off frequency is 0.47-0.67 Hz; when the analog integrator is only connected with the resistor R484, the cut-off frequency of the analog integrator is the second cut-off frequency, and the size of the cut-off frequency is 0.04-0.05 Hz.

The MCU singlechip controls the single-pole single-throw analog switch U5 to switch the critical resistors R484 and R486 of the analog integrator. In this embodiment, when the resistors R486 and R484 are connected to the circuit at the same time, the cutoff frequency of the analog integrator may be 0.67Hz, and when only the resistor R484 is connected to the circuit, the cutoff frequency of the analog integrator is 0.04 to 0.05Hz, specifically 0.04Hz, or 0.05Hz, so that the hardware baseline filtering frequency is adjustable.

In this embodiment, the cutoff frequency of the analog integrator is determined by the resistor R484, the resistor R486 and the capacitor C271, and the calculation formula is as follows:

wherein, V_REFRepresenting the output voltage, V, of an analog integrator_o-acDenotes an alternating current component of the electrocardiographic signal, τ denotes a time constant, τ denotes RC (R484// R486), and f denotes a cutoff frequency of the analog integrator.

When the cutoff frequency of the analog integrator is determined, the sizes of the resistor R484, the resistor R486 and the capacitor C271 may be reversely determined by the RC circuit, and specific values may be determined according to actual situations.

Different from the prior art, the electrocardiosignal of the human body is obtained and amplified by the signal amplification module; a filtering frequency adjusting instruction is obtained through a switch module to change the cut-off frequency of the analog integrator, so that the subsequent baseline filtering frequency is adjustable; the analog integrator integrates the electrocardiosignal amplified by the signal amplification module according to the cut-off frequency, and feeds back the integration result to the signal amplification module so that the signal amplification module outputs the electrocardio amplification signal with constant direct current voltage, so that the signal amplification module can keep the constant direct current output voltage even if the skin contact resistance changes in the electrocardio signal acquisition process, and the baseline drift interference is reduced; and filtering and sampling the electrocardio amplified signal through a control module to finally obtain an electrocardio digital signal convenient to analyze. The method and the device can realize adjustable baseline wander filtering frequency, and improve the applicability and filtering effect of baseline wander hardware filtering.

The application also provides an electrocardiosignal sampling system, which comprises a sensing module, an electrocardio baseline drift filtering device and/or an instruction input module; the sensing module is electrically connected with the electrocardio baseline drift filtering device, and/or the instruction input module is electrically connected with the electrocardio baseline drift filtering device; the sensing device adopts an acceleration sensor.

The sensing module is used for detecting human body movement information and transmitting the human body movement information to the electrocardio baseline drift filtering device; the instruction input module is used for manually inputting a filtering frequency adjusting instruction; the electrocardio baseline filtering device is used for triggering an internal filtering frequency adjusting instruction when the human body movement information exceeds a preset threshold value so as to switch the cut-off frequency of the corresponding analog integrator and realize baseline filtering of different frequencies; and/or the electrocardio baseline filtering device is used for acquiring a filtering frequency adjusting instruction transmitted by the instruction input module so as to switch the cut-off frequency of the corresponding analog integrator to realize baseline filtering of different frequencies.

In this embodiment, the acceleration sensor may be a three-axis acceleration sensor; the instruction input module can be a mouse key device or a touch screen; the preset threshold is determined according to actual conditions.

It should be noted that the baseline filtering frequency can be automatically adjusted through the sensing module and the electrocardiogram baseline filtering device; the filtering frequency adjusting instruction can be manually input on the mouse key device or the touch screen, and then the baseline filtering frequency is adjusted through the electrocardio baseline filtering device.

Referring to fig. 6, the present application further provides an electrocardiograph signal sampling method, which is applied to the electrocardiograph signal sampling system of the present application, and the method includes:

s1: acquiring human body movement information, wherein the movement information comprises movement acceleration and duration;

s2: judging whether the human body movement acceleration exceeds a preset acceleration threshold value or not and whether the duration time exceeds a preset time threshold value or not;

s3: if so, triggering a first filtering frequency adjusting instruction to enable the electrocardio baseline filtering device to be switched to a first cut-off frequency to filter and sample electrocardio signal baseline noise to obtain a filtered electrocardio digital signal; wherein the first cutoff frequency is greater than the second cutoff frequency;

s4: if not, triggering a second filtering frequency adjusting instruction to enable the electrocardio baseline filtering device to be switched to a second cut-off frequency to filter and sample electrocardio signal baseline noise to obtain a filtered electrocardio digital signal.

In this embodiment, the first filtering frequency adjustment command refers to a control command for switching to relatively high frequency filtering; the first cutoff frequency is 0.67Hz or 0.47 Hz; the second filtering frequency adjusting instruction is a control instruction for switching to relatively low-frequency filtering; the second cut-off frequency is 0.05Hz or 0.04 Hz.

It should be noted that, in the three-axis acceleration sensor adopted in this embodiment, three axes respectively correspond to three directions of human motion, and then the accelerations in the three directions are subjected to data processing, in this embodiment, a quadratic square root method of a square sum is adopted to calculate the accelerations in the three directions, so as to obtain a final movement acceleration, and when the movement acceleration of the human exceeds an acceleration threshold and a duration time exceeds a preset time threshold, a first filtering frequency adjustment instruction is triggered, so that the electrocardiographic baseline filtering device performs filtering sampling with respect to a high-frequency, so as to obtain a corresponding filtering signal; and when the moving acceleration of the human body does not exceed the acceleration threshold or the duration time does not exceed the preset time threshold, triggering a second filtering frequency adjusting instruction so that the electrocardio baseline filtering device carries out filtering sampling relative to the low frequency to obtain a corresponding filtering signal. In one embodiment, the time threshold for the duration may be 2s, 3s, or 4s, and the acceleration threshold may be determined based on actual conditions.

In addition, the electrocardiosignal sampling method can be written into the main control unit of the electrocardio baseline filtering device in an embedded mode, and can also be integrated in independent electronic equipment.

The electrocardiosignal sampling method can automatically adjust the filtering frequency according to the movement condition of the human body, thereby improving the effectiveness of electrocardiosignal filtering and sampling, and being more intelligent and convenient.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above.

The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application.