CN204181614U - Based on DSP Electro-cadiogram signals detector system - Google Patents

Based on DSP Electro-cadiogram signals detector system Download PDF

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CN204181614U
CN204181614U CN201420648059.7U CN201420648059U CN204181614U CN 204181614 U CN204181614 U CN 204181614U CN 201420648059 U CN201420648059 U CN 201420648059U CN 204181614 U CN204181614 U CN 204181614U
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resistance
circuit
electric capacity
operational amplifier
signal
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孙会楠
丁文飞
邢彦辰
禹永植
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Abstract

Based on DSP Electro-cadiogram signals detector system, relate to a kind of Electro-cadiogram signals detector system.It is automatization in order to realize ecg analysis, miniaturization and networking.It comprises electrocardiosignal and extracts and conditioning unit and ECG's data compression circuit unit; The electrocardiosignal of two electrocardioelectrode collections successively exports DSP to after pre-amplification circuit, filter circuit, main amplifying circuit, voltage lifting circuit; The power supply signal outfan of power circuit is connected with the power supply signal input of DSP; The JTAG debugging interface signal end of JTAG debugging interface is connected with the JTAG debugging interface signal end of DSP; The communication interface signal end of communication interface is connected with the communication interface signal end of DSP; The keyboard signal outfan of keyboard is connected with the keyboard signal input of DSP.This utility model is applicable to ECG signal sampling.

Description

Based on DSP Electro-cadiogram signals detector system
Technical field
This utility model relates to a kind of Electro-cadiogram signals detector system.
Background technology
Biomedical signals measuring and signal processing technology can assist research that is biological and physiological system, assist to carry out Diagnosis and Treat to patient.In all biological signal measurings, be that the physiological measurements of the blood circulation of representative develops comparatively fast comparatively speaking with electrocardio, it is one of clinical device inspection method.To some disease, especially the diagnosis of cardiovascular disease is significant.Because its importance occupies a high position for each physiological amount, the detection therefore better realizing electrocardiosignal is necessary.
Electro-cadiogram signals detector system is applied to clinical existing last 100 years history.According to statistics, every annual has millions of population to die from cardiovascular disease in the world, therefore, to the diagnosis of cardiovascular disease, treatment always pay attention to by countries in the world medical circle.Ge great Medical Instruments manufacturer of the world competitively drops into exploitation, the production and selling that a large amount of human and material resources carry out Electro-cadiogram signals detector system, facilitates the development of cardiac electricity detecting system and popularizes.Particularly nearly ten years, along with the fast development of microelectronic computer technology, the overall performance of Electro-cadiogram signals detector system obtains large increase, and function is day by day perfect, and it is further convenient to operate.Traditional uniconductor table electrocardiographic recorder technology just towards digitized, the future development of leading synchronous electrocardiographic recording more, and will progressively be led more synchronous recording Electro-cadiogram signals detector system substitute.Release digitized 12 first from Marquette company of the U.S. in 1978 to lead synchronous electrocardiosignal detection system, just start new era of electrocardiographic recorder, analysis and diagnosis, preservation and management.And technology of tracing is from quartz fibre to directly shaking pen, also substituted by the hot configuration way of output of high-performance of new generation, record then adopts high-resolution laser printer.Here it is a new generation electrocardio pattern, provide convenience as a kind of important means of heart disease diagnosis for applying electrocardiogram clinically.At present, in the developed country such as American-European-Japanese, universal due to electrocardioscanner, makes them possess to enrich clinical knowledge and many measuring methods and theory.
Due to the industrial overall development level of China and the reason of armarium original base aspect, the scientific research of domestic Electro-cadiogram signals detector system, produce also there is a certain distance compared with international most advanced level, product can't meet growing market demand, therefore, the electrocardiograph major part of high, precision and frontier depends on import.And the most price comparison of imported product is expensive, the unable purchase of middle and small hospital, has had a strong impact on electrocardiograph in the application of China and popularization, thus has constrained the rescue of critical patient.Functionally, a domestic instrument generally only possesses a kind of functional analysis, as 12 lead electrocardiogram monitors can only analytic routines electrocardiosignal, high frequency electrocardiogram detector can only analysis of high frequency electrocardiosignal etc.Comprehensively check, must purchase several instruments simultaneously, the cost of equipment of its costliness only has strong large hospital to bear.
Along with integrated circuit technique, computer and network technologies going deep into further at medical domain, the research and development trend of cardiac electricity detecting system mainly comprises the following aspects from now on:
1, ecg analysis automatization: from current relevant information both domestic and external, the progress of Electrocardiographic analysis automated not making a breakthrough property.Mainly because electrocardiosignal is too complicated, also lack a set of gratifying algorithm at present.Therefore, also need to make a large amount of research work in automatic analysis field.Multiple method alternate analysis is a focus of development at present, as wavelet analysis, pattern recognition, neutral net etc.
2, miniaturization: gather the development of synchronization along with integrated circuit technique, EGC detecting Instrument is tending towards miniaturization and portability.As portable ecg monitor represents this development trend.
3, networking: along with the development of network technology, tele-medicine and diagnostic system also slowly start occur, ECG detecting equipment can be connected with the Internet the collection in worksite realizing electrocardiosignal by this, and instantaneous transmission and remote diagnosis will be important directions of future development.So more be conducive to medical resource to share, the development of electrocardio medical science.
4, gather and store data normalization: setting up ecg information data transmission standard unified in the world, the ECG information of the ECG detecting equipment collection enabling employing dissimilar is mutually transmitted and exchanges, the most frequently used and the widest universal data base is MIT-BIH standard cardioelectric Signals Data Base now, and the foundation of data base is conducive to sharing and communication for information of resource.
Summary of the invention
The present invention is automatization in order to realize ecg analysis, miniaturization and networking, thus provides a kind of based on DSP Electro-cadiogram signals detector system.
Based on DSP Electro-cadiogram signals detector system, it comprises electrocardiosignal and extracts and conditioning unit and ECG's data compression circuit unit;
Electrocardiosignal is extracted and conditioning unit comprises two electrocardioelectrodes (11), pre-amplification circuit (12), filter circuit (13), main amplifying circuit (14), voltage lifting circuit (15) and driven-right-leg circuit (16);
Two electrocardioelectrodes are for gathering human ecg signal; The electrocardiosignal outfan of described two electrocardioelectrodes is connected with two electrocardiosignal inputs of pre-amplification circuit (12) respectively; First signal output part of described pre-amplification circuit (12) is connected with the signal input part of filter circuit (13); The signal output part of described filter circuit (13) is connected with the signal input part of main amplifying circuit (14); The signal output part of described main amplifying circuit (14) is connected with the signal input part of voltage lifting circuit (15); The secondary signal outfan of pre-amplification circuit (12) is connected with the signal input part of driven-right-leg circuit (16); The signal output part of described driven-right-leg circuit (16) acts on human body;
ECG's data compression circuit unit comprises power circuit (21), TMS320F2812 type DSP(22), JTAG debugging interface (23), communication interface (24) and keyboard (25);
Electrocardiosignal outfan and the TMS320F2812 type DSP(22 of voltage lifting circuit (15)) electrocardiosignal input be connected; Power supply signal outfan and the TMS320F2812 type DSP(22 of power circuit (21)) power supply signal input be connected; JTAG debugging interface signal end and the TMS320F2812 type DSP(22 of JTAG debugging interface (23)) JTAG debugging interface signal end be connected; Communication interface signal end and the TMS320F2812 type DSP(22 of described communication interface (24)) communication interface signal end be connected; Keyboard signal outfan and the TMS320F2812 type DSP(22 of keyboard (25)) keyboard signal input be connected.
Two electrocardioelectrodes (11) are AgCl sensor.
Filter circuit (13) comprises electric capacity C 32, resistance R 34, resistance R 38, resistance R 39, electric capacity C 33, electric capacity C 34with operational amplifier U3;
Described electric capacity C 32one end be the signal input part of filter circuit (13); Electric capacity C 32the other end simultaneously with resistance R 34one end and resistance R 38one end connect; Described resistance R 34other end ground connection; Resistance R 38the other end connect electric capacity C simultaneously 33one end and resistance R 39one end; Described resistance R 39the other end simultaneously with electric capacity C 34one end be connected with the positive input of operational amplifier U3; Described electric capacity C 34other end ground connection; The outfan one electric capacity C of the reverse input end concatenation operation simultaneously amplifier U3 of operational amplifier U3 33the other end; The outfan of described operational amplifier U3 is the signal output part of filter circuit (13).
Main amplifying circuit (14) comprises resistance R 46, resistance R 47, resistance R 48, resistance R 49, resistance R 50, resistance R 51, electric capacity C 40, electric capacity C 41, operational amplifier U6 and operational amplifier U7;
Resistance R 46one end be the signal input part of main amplifying circuit, described resistance R 46the other end simultaneously with resistance R 47one end be connected with the reverse input end of operational amplifier U6; Described resistance R 47the other end simultaneously with outfan and the electric capacity C of operational amplifier U6 40one end connect;
The positive input of operational amplifier U6 and resistance R 48one end connect; Described resistance R 48other end ground connection;
Electric capacity C 40the other end and resistance R 49one end connect; Described resistance R 49the other end simultaneously with reverse input end, the resistance R of operational amplifier U7 50one end and electric capacity C 41one end connect; Described electric capacity C 41the other end simultaneously contact resistance R 50the other end be connected with the outfan of operational amplifier U7; The positive input of operational amplifier U7 and resistance R 51one end connect; Described resistance R 51other end ground connection.
Voltage lifting circuit (15) comprises electric capacity C 46, resistance R 52, resistance R 53with operational amplifier U8;
Electric capacity C 46one end be the signal input part of voltage lifting circuit (15), described electric capacity C 46the other end simultaneously with resistance R 52one end, resistance R 53one end be connected with the positive input of operational amplifier U8; The reverse input end of described operational amplifier U8 is connected with the outfan of operational amplifier U8; The outfan of described operational amplifier U8 is the signal output part of voltage lifting circuit (15).
Present invention achieves realize ecg analysis automatization, miniaturization and networking.
Accompanying drawing explanation
Fig. 1 is structural representation of the present invention;
Fig. 2 is that the I kind described in detailed description of the invention one is led principle schematic;
Fig. 3 is that the II kind described in detailed description of the invention one is led principle schematic;
Fig. 4 is that the III kind described in detailed description of the invention one is led principle schematic;
Fig. 5 is the connection diagram of pre-amplification circuit and driven-right-leg circuit;
Fig. 6 is the connection diagram of bandwidth-limited circuit;
Fig. 7 is the connection diagram of 50Hz trap circuit;
Fig. 8 is the connection diagram of main amplifying circuit;
Fig. 9 is the connection diagram of level lifting circuit;
Figure 10 is the connection diagram of the application principle circuit of power module;
Figure 11 is the connection diagram of system reset circuit;
Figure 12 is the connection diagram of clock circuit;
Figure 13 is the connection diagram that DSP is connected with artificial mouth;
Figure 14 is the connection diagram of TMS320F2812 and MAX232 interface circuit.
Detailed description of the invention
Detailed description of the invention one, based on DSP Electro-cadiogram signals detector system, it comprises electrocardiosignal and extracts and conditioning unit and ECG's data compression circuit unit;
Electrocardiosignal is extracted and conditioning unit comprises two electrocardioelectrodes (11), pre-amplification circuit (12), filter circuit (13), main amplifying circuit (14), voltage lifting circuit (15) and driven-right-leg circuit (16);
Two electrocardioelectrodes are for gathering human ecg signal; The electrocardiosignal outfan of described two electrocardioelectrodes is connected with two electrocardiosignal inputs of pre-amplification circuit (12) respectively; First signal output part of described pre-amplification circuit (12) is connected with the signal input part of filter circuit (13); The signal output part of described filter circuit (13) is connected with the signal input part of main amplifying circuit (14); The signal output part of described main amplifying circuit (14) is connected with the signal input part of voltage lifting circuit (15); The secondary signal outfan of pre-amplification circuit (12) is connected with the signal input part of driven-right-leg circuit (16); The signal output part of described driven-right-leg circuit (16) acts on human body;
ECG's data compression circuit unit comprises power circuit (21), TMS320F2812 type DSP(22), JTAG debugging interface (23), communication interface (24) and keyboard (25);
Electrocardiosignal outfan and the TMS320F2812 type DSP(22 of voltage lifting circuit (15)) electrocardiosignal input be connected; Power supply signal outfan and the TMS320F2812 type DSP(22 of power circuit (21)) power supply signal input be connected; JTAG debugging interface signal end and the TMS320F2812 type DSP(22 of JTAG debugging interface (23)) JTAG debugging interface signal end be connected; Communication interface signal end and the TMS320F2812 type DSP(22 of described communication interface (24)) communication interface signal end be connected; Keyboard signal outfan and the TMS320F2812 type DSP(22 of keyboard (25)) keyboard signal input be connected.
The difference based on DSP Electro-cadiogram signals detector system described in detailed description of the invention two, this detailed description of the invention and detailed description of the invention one is, two electrocardioelectrodes (11) are AgCl sensor.
The difference based on DSP Electro-cadiogram signals detector system described in detailed description of the invention three, this detailed description of the invention and detailed description of the invention one is, filter circuit (13) comprises electric capacity C 32, resistance R 34, resistance R 38, resistance R 39, electric capacity C 33, electric capacity C 34with operational amplifier U3;
Described electric capacity C 32one end be the signal input part of filter circuit (13); Electric capacity C 32the other end simultaneously with resistance R 34one end and resistance R 38one end connect; Described resistance R 34other end ground connection; Resistance R 38the other end connect electric capacity C simultaneously 33one end and resistance R 39one end; Described resistance R 39the other end simultaneously with electric capacity C 34one end be connected with the positive input of operational amplifier U3; Described electric capacity C 34other end ground connection; The outfan one electric capacity C of the reverse input end concatenation operation simultaneously amplifier U3 of operational amplifier U3 33the other end; The outfan of described operational amplifier U3 is the signal output part of filter circuit (13).
The difference based on DSP Electro-cadiogram signals detector system described in detailed description of the invention four, this detailed description of the invention and detailed description of the invention one is, main amplifying circuit (14) comprises resistance R 46, resistance R 47, resistance R 48, resistance R 49, resistance R 50, resistance R 51, electric capacity C 40, electric capacity C 41, operational amplifier U6 and operational amplifier U7;
Resistance R 46one end be the signal input part of main amplifying circuit, described resistance R 46the other end simultaneously with resistance R 47one end be connected with the reverse input end of operational amplifier U6; Described resistance R 47the other end simultaneously with outfan and the electric capacity C of operational amplifier U6 40one end connect;
The positive input of operational amplifier U6 and resistance R 48one end connect; Described resistance R 48other end ground connection;
Electric capacity C 40the other end and resistance R 49one end connect; Described resistance R 49the other end simultaneously with reverse input end, the resistance R of operational amplifier U7 50one end and electric capacity C 41one end connect; Described electric capacity C 41the other end simultaneously contact resistance R 50the other end be connected with the outfan of operational amplifier U7; The positive input of operational amplifier U7 and resistance R 51one end connect; Described resistance R 51other end ground connection.
The difference based on DSP Electro-cadiogram signals detector system described in detailed description of the invention five, this detailed description of the invention and detailed description of the invention one is, voltage lifting circuit (15) comprises electric capacity C 46, resistance R 52, resistance R 53with operational amplifier U8;
Electric capacity C 46one end be the signal input part of voltage lifting circuit (15), described electric capacity C 46the other end simultaneously with resistance R 52one end, resistance R 53one end be connected with the positive input of operational amplifier U8; The reverse input end of described operational amplifier U8 is connected with the outfan of operational amplifier U8; The outfan of described operational amplifier U8 is the signal output part of voltage lifting circuit (15).
Operation principle: system of the present invention is mainly divided into two large divisions: electrocardiosignal is extracted and modulate circuit part and ECG's data compression circuit part, namely analog-and digital-two parts.Electrocardiosignal is extracted and modulate circuit part comprises electrocardioelectrode and conducting wire, pre-amplification circuit, driven-right-leg circuit, filter circuit, main amplifying circuit and level lifting circuit.Wherein, the function of electrocardioelectrode and conducting wire extracts and transmission electrocardiosignal; Prime and rear class amplifying circuit are used for the amplification of electrocardiosignal; Driven-right-leg circuit then can suppress the common mode disturbances in electrocardiosignal; The function of filter circuit is low frequency, high frequency and 50Hz power frequency interference signals in filtering electrocardiosignal.
ECG's data compression circuit part forms primarily of DSP microprocessor, keyboard, power circuit, communication interface and JTAG debugging interface.Wherein, DSP microprocessor is responsible for the collection of electrocardiosignal and the process of various data; The FLASH memory of F2812 inside stores the various program codes of electrocardiogram monitor system, and power circuit provides the power supply required for system; Communication and JTAG debugging interface are then for cardiac electricity detecting system and miscellaneous equipment or network service etc.
The operation principle of system: first by AgCl sensor acquisition human ecg signal, by certain device that leads, signal is delivered to the process such as pre-amplification circuit tentatively amplifies, analog filtering process, main amplification, voltage lifting; Then the A/D converting unit applying DSP inside carries out the analog/digital conversion of data; Then, the electrocardiographicdigital digital signals collected is carried out Digital Signal Processing by DSP and obtain smooth, correct ecg signal data; Finally the digital electrocardiosignal after process is communicated with computer, result is stored in host computer, for the timely diagnostic analysis of medical personnel.
System electrode is selected: the quality of electrode pair electrocardiograph acquisition and recording electrocardiosignal is most important, employing should attach that power is strong, good permeability, absorbing sweat, electrodes conduct performance is good, polarizing voltage is low high-quality electrode, should be noted that the zest size to skin, the tired element such as permeability simultaneously.The performance of electrocardioelectrode generally can be divided into electrical property and paste performance.When electrocardioelectrode uses at short notice, only can consider the electrical property of electrode, but when electrode long-time (being often referred to more than 24h) uses, we not only require that electrode will have good electrical property, also to have good stickup performance, record out the Electrocardiographic object of high-quality to reach.
ECG signal sampling generally adopts external electrode.Along with the development in epoch, metal electrode oneself become the adapter of body surface.Body interior electric current is produced by ion motion, and the electric current in wire is produced by the motion of electronics.The effect of electrode is the electronic current be converted to by the ion current in body in metallic conductor.
Native system adopts Ag-AgCl electrode, and it is suppressed by argentum powder and chlorination argentum powder and forms, have highly sensitive, noise is low, polarizing voltage is little, the feature of good stability, is a kind of ideal body surface ecg detecting electrode.
Electrocardiosignal is led system
Clinically in order to unify and be convenient to compare obtained electrocardiographic wave, have strict Uniform provisions to the bind mode of the Electrocardiographic electrode position traced and lead-in wire and amplifier, this electrode group and its mode being attached to amplifier are called electrocardiogram lead or lead by people.According to the difference of electrode rest, can form various leading, the various electrocardiographic wave led respectively has feature.Have standard 12 to lead to be designated as I, II, III, aVR, aVL, aVF, V1 ~ V6 respectively at present for extensive use.Wherein I, II, III are bipolar lead, and aVR, aVL, aVF, V1 ~ V6 is unipolar lead.Bipolar lead when obtaining the potential difference of two test points, unipolar lead when obtaining certain current potential a bit relative to reference point.
I, II, III lead and are called standard limb lead, are called for short standard lead.It is with two limbs between potential difference to obtain body surface ecg, this mode of leading is adopted first clinically by Ai Yinhuowen.Three kinds of bipolar standard lead such as Fig. 3-5 show.In figure, A is amplifier, A cMfor driven-right-leg circuit.Electrode riding position and be with the connection of amplifier:
I leads: left upper extremity (LA) connects amplifier positive input terminal, and right upper extremity (RA) connects amplifier negative input end;
II leads: left lower extremity (LL) connects amplifier positive input terminal, and right upper extremity (RA) connects amplifier negative input end;
III leads: left lower extremity (LL) connects amplifier positive input terminal, and left upper extremity (LA) connects amplifier negative input end.
During standard lead, right lower extremity (RL) meets A all the time cMoutfan, indirect earthed.With V l, V r, V frepresent the potential value of left upper extremity, right upper extremity, left lower extremity respectively, then V i=V l-V r, V iI=V f-V r, V iII=V f-V l, often have V in a flash iI=V i+ V iII [26,27].
The feature of standard lead is the rough idea that can reflect heart more widely, as posterior myocardial infarction, arrhythmia etc., can be recorded to waveform change clearly in I leads or III leads.
Native system is single pass cardiac electricity detecting system, mainly uses to meet family, and many changes are not that very strong ECG signal does not have too large use for patient.Therefore, native system only have employed I and to lead mode.
Electrocardiosignal is low frequency, faint physiological signal, and body surface ECG generally only has 0.05 ~ 5mV, and frequency is between 0.05 ~ 100Hz, and energy mainly concentrates near 17Hz, and electromagnetic interference around large (particularly the Hz noise of 50Hz).To obtain the signal magnitude being convenient to microprocessor processes, the signal to noise ratio of electrocardiosignal need be improved, and the size of electrocardiosignal is amplified to enough amplitudes.Therefore, the effect of electrocardiosignal pre-amplification circuit seems particularly important.
Front end analogue amplifies and driven-right-leg circuit:
According to the feature of bioelectrical signals and the demand of this project, require that prestage amplifying circuit must have following characteristics:
1, high input impedance: that the electrocardiosignal extracted by electrode is the high internal resistance source of instability, faint bioelectrical signals, in order to reduce the impact of singal source resistance, must improve the input impedance of amplifier.From electrode polarization voltage, increase input impedance, reduce load current, can distorted signals be reduced.In general, require that the input impedance of electrocardio pre-stage amplifiers is greater than 5M Ω.
2, high cmrr CMRR: during electrocardio is measured, skin and electrode contact will cause polarizing voltage, if two electrode full symmetrics, this polarizing voltage numerical value is identical with phase place, will be input to ecg amplifier as DC common-mode signal; The interference of the physiological action beyond the Hz noise entrained by human body and measured parameter is also generally common mode disturbances.In order to reduce the interference of common-mode signal to useful difference mode signal, this just requires that prestage adopts the circuit of the differential amplify form that CMRR is high.
3, low noise: electrocardiosignal is faint AC signal, amplifier in needs enough signal to noise ratios.For preventing noise from being flooded by signal, filter preprocessing is carried out to signal.In addition, amplifying element should not increase extra noise again, should adopt the amplifier of low noise.
4, the null offset that low drifting causes due to electronic circuit variations in temperature makes the frequency of the frequency of drift current and amplitude and electrocardiosignal and amplitude very close.For preventing the interference caused of drifting about, improving accuracy of measurement, the amplifier with low drifting characteristic should be selected.
The Frequency Response of 5, suitable Frequency Response pre-stage amplifiers should adapt to the frequency range of electrocardiosignal.But be not that frequency response is more wide better, the electrocardiosignal frequency response width required as the design is that 0.05 ~ 100Hz is just much of that.If the frequency response of amplifier is designed to 0 ~ 10kH, make the garbage signals such as electromyographic signal be mixed on the contrary, the optimum signal-noise ratio of useful signal can not be guaranteed thus, thus affect follow-up ecg analysis.
6, small size, low-voltage, low-power consumption, the application scenario of low-voltage, low-power consumption is suitable for.
Comprehensively some requirement above-mentioned, selects INA118 as first order amplifier herein.It is the one in B-B company of the U.S. precision instrument amplifier series of producing, the advantage such as have that precision is high, low in energy consumption, common mode rejection ratio is high and working band is wide, is applicable to amplifying various tiny organism signal.INA118 forms differential amplification structure by three operational amplifiers.
INA118 is by an external resistance between foot 1 and foot 8 realize different gains, this gain can from 1 to 1000 not etc.Resistance large I by: formula determines, in formula, G is gain.
The effect of prestage amplifying circuit is the interfering signal that as far as possible decays, and to improve signal to noise ratio, its circuit diagram as shown in Figure 5.As long as adjustment figure peripheral resistance resistance just can accurately by the gain control of amplifier any one numerical value between 1 ~ 1000.Certainly, in order to avoid causing the saturated of circuit, the gain of amplifier prestage generally should below 100.In the design, prestage amplifying circuit amplification is set to non-adjustable, gets , namely gain is .
U2, R in Fig. 5 l1, R l2and C lform driven-right-leg circuit.Adopt the main purpose of right leg drive: one is prevent the common-mode voltage of amplifier differential input terminal floating excessive and cause amplifier saturation to lose amplification; Another is the interference reduced because the displacement current of human body causes.
From R 35and R 36resistive junction measures common-mode voltage, and it passes through resistance R after auxiliary inverting amplifier amplifies l2feed back to right lower limb.At this moment the displacement current of human body no longer flows into ground, but flows into R l2with the output of booster amplifier.R l2play safeguard protection effect, occur between patient and ground very high voltage time booster amplifier saturated, right leg drive is inoperative, and at this moment U2 is equivalent to ground connection, R l2now play current-limiting protection effect.The common-mode voltage Shunt negative feedback circuit of driven-right-leg circuit to be in fact exactly one with human body be summing point.Human body is as the inverting input of inverting amplifier, and the displacement current of all inflow human bodies is equal to the drive current on feedback resistance substantially.As long as the open-loop gain of amplifier A is enough large, even if so there is larger displacement current to flow through human body, the current potential of human body also can keep zero potential substantially.Adopt this driven-right-leg circuit, for 50Hz interference suppression not to lose Electrocardiographic radio-frequency component for cost, but because driven-right-leg circuit exists the feedback control loop of AC influence voltage, so alternating current may be had to flow through human body, this is unsafe factor, current-limiting resistance is large guarantee safety sufficiently, usually will get more than 1M Ω.
Filter circuit: bandwidth-limited circuit design electrocardiosignal is faint physiological signal, and frequency mainly concentrates on low-frequency range (0.05 ~ 100Hz), also there is a lot of signal electrocardiosignal being caused to interference beyond this frequency range.For the not disturbed signal disturbing of protection electrocardiosignal, a band pass filter circuit must be designed electrocardiosignal is protected, as shown in Figure 7.Native system is by C 32and R 34form high pass circuit, by LM324 amplifier, C 33, C 34, R 38and R 39form second order active low-pass filter circuit, they form bandpass filtering jointly.LM324 is conventional universal amplifier, the high and low power consumption of low price, precision, the low feature such as biased.
Main amplifying circuit: electrocardiosignal amplitude is about 5 μ V ~ 4mV (representative value is 1mV), it is 0 ~ 3.3V that the incoming level that A/D changes requires, though electrocardiosignal is amplified by front stage circuits, voltage amplitude is also not suitable for directly carrying out A/D conversion.Therefore, before A/D conversion, also need to amplify further electrocardiosignal, make its voltage amplitude meet A/D conversion requirements.Main amplifying circuit principle as shown in Figure 8.
Serial communication circuit: TMS320F2812DSP has a serial communication interface module (SCI), it adopts the asynchronous serial communication interface of dual-wire communications, main application standard is non-returns 0 (NRZ) data format, can carry out data communication with the asynchronous peripheral of CPU or other communication data format compatibility.SCI has the different baud rate of programmable 64K kind, 1 ~ 8 bit data length able to programme; Even-odd check, overload, frame mistake and interruption monitoring totally 4 error detection marks; Idle line and address bit two kinds wake multiprocessor mode up; Half-or full-duplex operates; Can work in interruption or inquiry mode, have independently receive and send interrupt enable.To be configured TMS320F2812 multiplexing general purpose I/O (GPIO) pin able to programme in actual applications, make it export SCITXD and SCIRXD signal.Interface circuit as shown in figure 14.
Because the serial ports of PC serial ports and TMS320F2812 is incompatible in logic level, can not directly be connected use.Could normal communication after needing the conversion carrying out being correlated with between two serial ports.At present, what serial communication port COM1 and COM2 on general PC adopted is RS-232 agreement, uses EIA-RS-232 level, carrys out presentation logic state with generating positive and negative voltage.And TMS320F2812 employing is Transistor-Transistor Logic level, carry out presentation logic state with low and high level.Therefore the MAX232 chip adopting TI to release a compatible RS232 standard herein realizes the two-way level converting of TTL ← → EIA-RS-232.Meanwhile, because the TMS320F2812 in the present invention belongs to low-power consumption, employing be that+3.3V powers, and MAX232 chip adopt+5V power, so need the typical electrical level matching circuit adding that TI company provides between MAX232 chip and TMS320F2812.1 diode (IN4007) and 3 resistance are adopted to carry out level match in native system.This interface circuit is simple, and reliability is higher.

Claims (5)

1. based on DSP Electro-cadiogram signals detector system, it is characterized in that: it comprises electrocardiosignal and extracts and conditioning unit and ECG's data compression circuit unit;
Electrocardiosignal is extracted and conditioning unit comprises two electrocardioelectrodes (11), pre-amplification circuit (12), filter circuit (13), main amplifying circuit (14), voltage lifting circuit (15) and driven-right-leg circuit (16);
Two electrocardioelectrodes are for gathering human ecg signal; The electrocardiosignal outfan of described two electrocardioelectrodes is connected with two electrocardiosignal inputs of pre-amplification circuit (12) respectively; First signal output part of described pre-amplification circuit (12) is connected with the signal input part of filter circuit (13); The signal output part of described filter circuit (13) is connected with the signal input part of main amplifying circuit (14); The signal output part of described main amplifying circuit (14) is connected with the signal input part of voltage lifting circuit (15); The secondary signal outfan of pre-amplification circuit (12) is connected with the signal input part of driven-right-leg circuit (16); The signal output part of described driven-right-leg circuit (16) acts on human body;
ECG's data compression circuit unit comprises power circuit (21), TMS320F2812 type DSP(22), JTAG debugging interface (23), communication interface (24) and keyboard (25);
Electrocardiosignal outfan and the TMS320F2812 type DSP(22 of voltage lifting circuit (15)) electrocardiosignal input be connected; Power supply signal outfan and the TMS320F2812 type DSP(22 of power circuit (21)) power supply signal input be connected; JTAG debugging interface signal end and the TMS320F2812 type DSP(22 of JTAG debugging interface (23)) JTAG debugging interface signal end be connected; Communication interface signal end and the TMS320F2812 type DSP(22 of described communication interface (24)) communication interface signal end be connected; Keyboard signal outfan and the TMS320F2812 type DSP(22 of keyboard (25)) keyboard signal input be connected.
2. according to claim 1 based on DSP Electro-cadiogram signals detector system, it is characterized in that two electrocardioelectrodes (11) are AgCl sensor.
3. according to claim 1 based on DSP Electro-cadiogram signals detector system, it is characterized in that filter circuit (13) comprises electric capacity C 32, resistance R 34, resistance R 38, resistance R 39, electric capacity C 33, electric capacity C 34with operational amplifier U3;
Described electric capacity C 32one end be the signal input part of filter circuit (13); Electric capacity C 32the other end simultaneously with resistance R 34one end and resistance R 38one end connect; Described resistance R 34other end ground connection; Resistance R 38the other end connect electric capacity C simultaneously 33one end and resistance R 39one end; Described resistance R 39the other end simultaneously with electric capacity C 34one end be connected with the positive input of operational amplifier U3; Described electric capacity C 34other end ground connection; The outfan one electric capacity C of the reverse input end concatenation operation simultaneously amplifier U3 of operational amplifier U3 33the other end; The outfan of described operational amplifier U3 is the signal output part of filter circuit (13).
4. according to claim 1 based on DSP Electro-cadiogram signals detector system, it is characterized in that main amplifying circuit (14) comprises resistance R 46, resistance R 47, resistance R 48, resistance R 49, resistance R 50, resistance R 51, electric capacity C 40, electric capacity C 41, operational amplifier U6 and operational amplifier U7;
Resistance R 46one end be the signal input part of main amplifying circuit, described resistance R 46the other end simultaneously with resistance R 47one end be connected with the reverse input end of operational amplifier U6; Described resistance R 47the other end simultaneously with outfan and the electric capacity C of operational amplifier U6 40one end connect;
The positive input of operational amplifier U6 and resistance R 48one end connect; Described resistance R 48other end ground connection;
Electric capacity C 40the other end and resistance R 49one end connect; Described resistance R 49the other end simultaneously with reverse input end, the resistance R of operational amplifier U7 50one end and electric capacity C 41one end connect; Described electric capacity C 41the other end simultaneously contact resistance R 50the other end be connected with the outfan of operational amplifier U7; The positive input of operational amplifier U7 and resistance R 51one end connect; Described resistance R 51other end ground connection.
5. according to claim 1 based on DSP Electro-cadiogram signals detector system, it is characterized in that voltage lifting circuit (15) comprises electric capacity C 46, resistance R 52, resistance R 53with operational amplifier U8;
Electric capacity C 46one end be the signal input part of voltage lifting circuit (15), described electric capacity C 46the other end simultaneously with resistance R 52one end, resistance R 53one end be connected with the positive input of operational amplifier U8; The reverse input end of described operational amplifier U8 is connected with the outfan of operational amplifier U8; The outfan of described operational amplifier U8 is the signal output part of voltage lifting circuit (15).
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104799854A (en) * 2015-04-29 2015-07-29 深圳大学 Surface myoelectricity acquisition device and myoelectricity signal processing method thereof
CN105125202A (en) * 2015-07-31 2015-12-09 苏州玄禾物联网科技有限公司 Electrocardiogram monitoring system based on low-noise amplifier
CN105125203A (en) * 2015-07-31 2015-12-09 苏州玄禾物联网科技有限公司 Electrocardiogram monitoring power supply control system
CN105249956A (en) * 2015-07-31 2016-01-20 苏州玄禾物联网科技有限公司 Electrocardiogram monitoring system based on amplified circuit
CN105686825A (en) * 2016-03-07 2016-06-22 浙江大学 Double-stage wearable household electrocardiocorder and method thereof
CN109199326A (en) * 2017-07-07 2019-01-15 聚和医疗器械（杭州）有限公司 Chinese medicine electromagnetic signal diagnosis and therapy system

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104799854A (en) * 2015-04-29 2015-07-29 深圳大学 Surface myoelectricity acquisition device and myoelectricity signal processing method thereof
CN105125202A (en) * 2015-07-31 2015-12-09 苏州玄禾物联网科技有限公司 Electrocardiogram monitoring system based on low-noise amplifier
CN105125203A (en) * 2015-07-31 2015-12-09 苏州玄禾物联网科技有限公司 Electrocardiogram monitoring power supply control system
CN105249956A (en) * 2015-07-31 2016-01-20 苏州玄禾物联网科技有限公司 Electrocardiogram monitoring system based on amplified circuit
CN105686825A (en) * 2016-03-07 2016-06-22 浙江大学 Double-stage wearable household electrocardiocorder and method thereof
CN109199326A (en) * 2017-07-07 2019-01-15 聚和医疗器械（杭州）有限公司 Chinese medicine electromagnetic signal diagnosis and therapy system

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