FR2508202A1 - MICROPROCESSOR ELECTROCARDIOGRAM ANALYZER - Google Patents

Abstract

THE INVENTION CONCERNS ELECTROCARDIOGRAM ANALYZERS. THE ANALYZER OF THE INVENTION OPERATES IN ACCORDANCE WITH AN ESTABLISHED PROTOCOL FOR A STRESS TEST FOR OBSERVING THE FUNCTIONING OF THE PATIENT'S HEART DURING EXERCISE. THE ESSENTIAL ELEMENT OF THE ANALYZER IS A MICROPROCESSOR 12 WHICH COMMUNICATES WITH VARIOUS PERIPHERALS 14, 15, 16 THROUGH A PERIPHERAL ADAPTER 13. THERE IS ALSO A SPECIAL SELF-ADAPTIVE FILTER 2, 3, 4 INTENDED TO ELIMINATE INTERRUPTIONS RELATED TO THE FREQUENCY OF THE SECTOR. APPLICATION TO MEDICAL EQUIPMENT.

Description

The present invention relates to an analyzer for

  trocardiograms equipped with a microprocessor, ie a

  apparatus for automatically analyzing electro-

  diagrams, on the basis of the protocol laid down for an ef-

strong.

  We know that we can record on different

  your heart muscle conditions using an electrocardiogram

  diographer who forms characteristic curves

  a definite correlation between the pathological state of the mus-

  heart shape and the shape of the curves, so that

  Cardiologists can recognize different pathological conditions

  by analyzing these curves, that is, by evaluating

parameters.

  The usual visual analysis of electrocardiology

  recorded gram is an operation with a character of

  routine that is relatively tedious and time consuming.

  As a result, results are often highly dependent on the individual's disposition and attention, and

  they also depend on his knowledge and experience.

Experience.

  With the development of computers offering

  great possibilities, an automatic analysis of electro-

  diogrammes has also become possible So far, two kinds of devices have been developed worldwide for such analyzes the first group includes large computer systems recording huge amounts of data, ie cardiographic recordings ,

  but these systems operate indirectly, that is,

  say that electrocardiograms are recorded first, for example on a magnetic tape, after which the electrocardiograms are transferred to the data processing computer. The second group includes small devices

  transportable, which analyze the electrocardiograms

  While some of the devices use hard-wired logic, there have also recently appeared devices of this type whose operation is based on the use of a hard-wired logic. microprocessor system, as a

  control and supervision unit.

  The characteristics of these known devices re-

  essentially because, on the one hand, they avoid the aforementioned imperfections of the visual analysis of electricity.

  recorded trocardiogram, which leads to an ob-

  of the pathological state, and, on the other hand, they

  the disadvantage that they are fundamental-

  intended for particular embodiments of cardio equipment, which undoubtedly

their possibilities of use.

  The object of the invention is to provide a microprocessor electrocardiogram analyzer which is fully

  able to work with the output information of the elec-

  existing standard trocardiographs, thus enabling the retrofitting of existing equipment The analyzer operates in accordance with a procedure provided for the exercise test, that is to say for a situation in which the patient is subjected to physical exertion and in which we

  simultaneously observes the functioning of his heart.

  The invention will be better understood on reading the

  description that follows of an embodiment and in

  Referring to the accompanying drawings in which: Figure 1 is a block diagram of the analyzer according to the invention;

  Figure 2 is a characteristic form of electricity.

  trocardiogram, with the most important parameters required

analysis;

  FIG. 3 is a diagram of a self-adapting filter

  special tif, according to the invention, for eliminating disturbances related to the frequency of the sector; and FIG. 4 is a diagram of a generator circuit

  pulses that connect the function buttons to the process

  and the device adapter.

  As is evident from Figure 1,

  the analyzer according to the invention comprises a pass filter

  1, circuits 2, 3, 4 for eliminating the disturbances

  produced by the sector, a high-pass filter 5, a

  multiplexer circuit 6, an output interface 7, a demul-

  Tiplexeur 8, a 10-bit analog-to-digital converter,

  9, a random access memory 10, a memory module 11, a micro-memory module

  8-bit processor, 12, an adapter 13, an alpha keyboard

  digital 14, a digital display device 15, a printer 16 and a programmed clock 17 As shown in FIG. 1, the multiplexer circuit 6 has inputs intended to be connected to any device

  conventional recording, that is, electrocardiography.

  graph, in which the usual outputs are then used.

  OSCILLO 500 CPE the output of the interface 7 is connected to the input of the multiplexer 6, and to the input of the demultiplexer 8, while the output of the multiplexer 6 is connected to the input of the pass filter. 1 down the output of this filter 1 is connected to the input of circuits 2 S 4 for eliminating disturbances related to the sector, and the input of circuit 3 is connected to the output of circuit 2 for eliminating disturbances of the sector the output of the circuit 3 is connected to the second input of the circuit 4, intended to eliminate disturbances of the sector, the output of this circuit 4 is connected to the input of the filter

  : high pass 5 whose output is connected to the input of the con-

  10-bit digital analog converter, the output of this converter is connected on the one hand to the input of the output interface 7 and on the other hand to the peripheral adapter 13, which is otherwise connected to the RAM 10, the memory module 11, the 8-bit microprocessor,

  12, which can be for example a NC 6800, and the clock pro-

  The peripheral adapter 13 is connected on the other hand to the alphanumeric keyboard 14 and to the display device 15, presenting the time and the heart rate,

and to the printer 16.

  Figure 3 shows in detail the self-filtering

  high-quality adaptive device for the elimination of

  sector-related turbulence In this filter, the anode of the

  diode D 20 is connected to a winding separated from the trans-

  power trainer by the sector, and its cathode is connected by the resistor R 20 to the base of the transistor

  NPN T 20, whose transmitter is connected to the ground.

  This transistor receives the supply voltage + VDD through the resistor R 21 pt and is also connected to one of the inputs of the voltage-controlled oscillator 21. The output of the oscillator 21 is connected to the input of the oscillator 21. bit counter 22 whose outputs I 20, I 21, I 22 and I 23 are

  connected to the control inputs of the analogue switches

  23, 24 The outputs of the analog switches 23,

  24 are connected to an armature of the capacitors C 230 -

  C 246, whose other armatures are connected together and are connected to one end of the variable resistor P and to the input of the separator stage. The output of the stage is connected to the input of the pass filter. bottom 30 whose output is connected to the input of the high-pass filter 31 La

  output of this filter is connected to the input of the addition-

  neur 40 via variable resistor P 32 'and this same input is connected to the other end of

  the variable resistance P 20 by the resistance R 40 and the

  nector for the signal V 21 The output of the adder 40

  is connected to the input of the analog-to-digital converter

that 9.

  As mentioned earlier, Figure 4 represents

  the pulse generator circuit for connecting the function buttons on the keyboard to the processor and the peripheral adapter This circuit includes diodes

  D 140, D 141 and D 142 and resistors R 140, R 141 and R 142.

  The connection points between each diode-resistance pair

  with the references V 140, V 141 and V 142 are respectively

  connected to the three function buttons ANALYSIS, INTER-

  RUPTION, STOP, which connect these inputs to the ground

  Anodes of the diodes are connected together and they are

  connected by the resistor R 143 to the base of the PNP transistor T 140, while the capacitor C 140 is connected between the base and the emitter of the transistor T 140 The collector of the transistor T 140 is connected to the clock input C 1 of the

  flip-flop type D in IC 140.

  The resistor R 145 is connected between the inputs R 1 and Q, while the input R 1 is further connected to ground by the capacitor 0141. Similarly, the resistor R 146 is connected between the inputs R 2 and Q 2 'and the diode

  D 143 is connected in parallel with the resistor R 1460

  RI is further connected to ground by the capacitor 0142 the output I 140 of the latch IC 140 is connected to the

processor 12-

  The rest of the description will focus on the function

  the microprocessor electrocardiogram analyzer

  Processor 12, for example of the type N 06800, executes program commands that are stored in the module.

  of memory 11, for example of the TMM 323 type.

  moire 11 contains a program which fixes the functioning of the whole system, that is to say the functional part, and the analytical algorithms intended for the definition of

  cardiological parameters, that is, the analytic part.

  At the beginning of the operation of the device, the

  date and time registration is given via the printer 16 The operator introduces

  the answer by the alphanumeric keyboard 14 The system

  the answer by the device adapter 13, which

  is, for example, of type NC 6821, and it starts the clock.

  programmed age 17, for example of the type N 16840, which, starting from

  of this moment, indicates the exact time on the day of the

  until the system is shut down by

  the power supply of the microprocessor 12.

  The connection to an electrocardiograph of a mode of

  classical realization allows to receive from this last

  deny amplified bioelectrical signals that enter the multiplexer circuit using the keyboard 14 that makes

  operate the system in accordance with the program, and

  making a call directed to the peripheral adapter 13, it is possible to record in the output interface 7 a code

  defining the channel to be analyzed This code is

  transferred to the demultiplexer 8, which

  the illumination of the light-emitting diode indicator

corresponding to the chosen channel.

  Before the actual test, we can introduce

  by the keyboard 14 all the data concerning the patient.

  All the data is printed on the printer 16, that is,

  that is: indication of the apparatus with which the patient's test is performed, namely an ergometer or a squirrel-type apparatus; first and last name of the patient; age, sex, weight and information about the patient's physical activity; patient number; name of the doctor in charge of the treatment;

transfer diagnosis.

  Before the test or immediately after, a function

  can be activated on the keyboard, at the request of

  program, this function transfers to the

  the data entered by the keyboard 14 From this

  In this way, it is possible to make observa-

  individual comments and comments, in addition to the

standard procedure.

  Each electrocardiograph contains a reference source providing a voltage of 1 m V which is used for calibration. Before the start of the test itself, this signal must be applied to the analyzer in the form of a rectangular pulse train. Under the effect of a request

  keyboard 14, a calibration algorithm

  is triggered to form a digital equivalent of 1 mV, based on the analog input pulses. The analog signal then passes from the multiplexer 6 to the

  10-bit analog-to-digital converter, 9, through

  a series of active analog filters 1, 2, 3, 4 and 5 which will be described later The converter 9

  samples the input signal with a specified frequency

  and the converter is controlled by the programmed clock 17 The individual samples are recorded in series in a defined position in the RAM 10, which is

  for example of the type TMM 314 the program allows recognition

  the positive and negative jumps on either side of the input signal, so as to record eleven samples each in the region between one jump and the next. To these uniformly distributed samples are added samples of eight calibration pulses

  following, thanks to which the average difference between the

  Before and after the positive and negative jumps of the signal, and after them, represents the digital equivalent of the calibration signal, ie 1 m V The number received is recorded in the

RAM 10.

  The programs executed by the analyzer in accordance with the invention provide for two starting methods. According to one of them, the measurement of time representing the duration of the test is not yet introduced, and according to the other, the measurement of

  time is introduced All other start-up operations

  The electrocardiogram signal is identical

  shown in FIG. 2, whose shape corresponds to

  left precordial electrodes must pass through the

  In a stress test, such a signal is accom-

  accompanied by several types of disturbances: -

  because of poor contact of the electrodes with the surface

  this of the skin and because of the muscular potentials, it appears disturbances whose frequency spectrum

  is preponderantly higher than the frequencies con-

  naked in the electrocardiogram signal; the breathing and the movement of the thorax show a low frequency drift of the baseline which is superimposed on the fundamental signal; another disturbance factor is the frequency of the 50 Hz sector, which is in the spectrum of

  frequency of the electrocardiogram signal.

  All these disturbances must be eliminated,

  and that's why we use the analog filters

  active logic 1-5 mentioned above These filters operate in the following way: the low-pass filter 1 eliminates the high frequencies and the high-pass filter 5 eliminates the low-frequency noise The combination of the circuits 2, 3, 4 ensures the elimination of sector-related disturbances It is important here that the frequency of

  sector is mitigated as much as possible without the

  quences close to the frequency of the sector are excessive.

  affected by the fact that the frequency of the sector is

  not perfectly constant, it would not always be possible

  The solution is to use a transversal filter which guarantees a high quality while allowing

  to vary its central frequency with a general

  external pulse generator without any change in

transmission curve.

  The filter shown in FIG. 3 for the elimination of mains-related disturbances operates in the following manner. The control signal generated by the separate winding of the mains transformer by the mains, which is a sinusoidal to the

  sector frequency, is applied by the V 20 input to the tran-

  sistor 1 PN T 20, which forms from this signal a train of rectangular pulses These pulses synchronize the voltage-controlled oscillator 21 whose rest frequency is set at approximately N times the value of the frequency of the sector, in the where the number of states of the bit counter 22 is equal to 2 Because this counter 22 is a frequency divider connected in the feedback loop

  for the voltage-controlled oscillator 21, the latter oscillator

  the at a frequency that is exactly N times higher than the

  frequency of the mains The outputs of the counter 22, that is to say

  I 20, I 211 I 22 and I 23, are connected to the control inputs of the analog switches 23, 24 which separately switch to ground N capacitors, one after the other, at the rate of the oscillator 21. signal that is directed to the variable resistor P 2 o through the input V 21 enters into

  the transverse filter described above, which transmits only

  the clock frequency, i.e. the mains frequency and its harmonic frequencies The separator stage 25 directs the separated signal components to a filter

  low pass 50, which eliminates the higher harmonic frequencies

  and to a high-pass filter 31 which compensates for the transmission characteristic of the transverse filter at

  very low frequencies Only disturbances at frequency

  When the sector reaches the adder 40, with an offset of 180 By using a variable resistor P 32, it is possible to regulate the amplitude of this signal so as to obtain a complete compensation of the disturbances which are applied at the same time. that the useful signal, by the direct line involving the resistor R 40 In this way, the frequencies of the sector are attenuated about

  d B in the output signal Its quality of the attenuation filter

  The description described depends on the value of the variable resistor P 20, the value and the number of the switched capacitors C 23 OO 246 and the central frequency CO, that is to say the frequency of the oscillator: cw : NP 2 O a

Y N * 20 O

  by denoting by C the value of the switched capacitors in

  P, by N their number and by P 20 the set value of the

variable resistance, in ohms.

  The filtered signal reaches the input of the analog-digital converter 9, that is to say of a circuit of the type

  AD 574 JK, which converts this signal into a series of digits.

  The sampling is done at a frequency defined by a program, for example 500 Hz, which is imposed by the programmed clock 17 The samples are transferred

  and are stored in the RAM 10 while, if-

  simultaneously, the program looks for isolated QRS complexes (systoles in the input signal) As soon as a QRS complex

  is found, is evaluated and classified according to procedures

  mathematical dice in the category "normal systole" or in the category "extra-systole" The extra-systoles are

  further divided into supraventricular systoles and

  ventricular sheets, and the number of both types is

  read in special positions in RAM 10

  for the duration of the test An average systole is

  with normal systoles and is represented by a sequence of 256 samples and is recorded in the

RAM 10.

  Each detection of the QRS complex triggers a programmed heartbeat rate conversion. The calculated value is transmitted by the peripheral adapter 13 to the 7-segment digital light display device. the duration of the test the time which indicates (in minutes and seconds) the duration during which the patient is under stress.

  of time are set by the programmed clock 17 which

  the processor 12 using the program from the

  memory module 11 and with the help of the interrupt line

  The display devices 15 are controlled by the

  processor 12 via the perimeter adapter

  At the moment the patient's effort begins, it is necessary to press the START button on the keyboard

  14 This starts the clock 17, by means of a code de-

  completed, which has the effect of triggering the

  sampling, detection, averaging

  and display system described above In addition to the

  START and alphanumeric buttons, which generate

  all a corresponding hexadecimal code, the keyboard 14 com

  also has non-coded buttons These buttons allow

  attempt to request an analysis of the input data (ANALYSIS), an interruption of the patient's effort (INTERRUPTION) and a complete stop of the test (STOP) When one is pressed

  of these buttons, the unmasked interrupt line of the pro-

  12 is activated, ie this stops

  operation of the processor 12, regardless of the activity

  of the latter at the moment considered, even if it is

  routine interruption Of course, such an in-

  absolute derogation should not be prolonged during a

  because, in this case, all the functions of the

would stop.

  The circuit described above and shown in Figure 4 is such that when pressing one of the three buttons mentioned above, this triggers a pulse duration of about 3 Fs only, even if we have press the button for a much longer time or if you pressed several times in succession In this circuit, there is a transistor PNP T 140 which, when pressing any of the function buttons, generates a jump positive voltage and operates as an inverter It will be noted that because of the diodes D 140 = D 141 and D 142 and the resistors R 140, R 141 and R 142, the function buttons are connected in a circuit configuration OR The capacitor C 140 eliminates the random disturbances and voltage spikes that result from the bouncing of contacts when

  press the button At the moment of switching the

  tor T 140, the voltage jump is transferred to the clock input.

  in box C of the D-type flip-flop which forms part of the IC 140, which causes a high voltage level to appear on the output Q 1 of the flip-flop IC 140 and a low voltage level appears on the output Q 1 After a time which is defined by the components R 145 and C 141 'a

  restoration pulse appears on the R 1 input of the base

  This causes the Q 1 output to go to a low voltage level and the Q 1 output to a high voltage level.

  change instantly causes the switching of the

  D-type flip-flop, which is also part of the circuit

  As a result, a low voltage level is established.

  bli on the output Q 2, which makes it impossible to change the state of Q 1 or Q 1, via the input D 1 Ce

  blocking is prolonged until a moment, defined by the

  R 146 and C 142 'to which the second flip-flop is restored

  by the input R 2 The diode D 143 contributes to enabling a de-

  fast charge of the capacitor C 142, so that the circuit is ready for a new cycle, in the way that we come

to describe.

  the lines V 140 '141 and V 142 are also con-

  connected to the peripheral adapter 13 so as to transmit

  supplying information to the processor 12 regarding the button that generated the interrupt As previously described, the interrupt pulse is generated on the Q 1 output of the flip-flop and is transferred directly to the unmasked interrupt input of the processor 12, by the line which is connected to the output I 1400 Under the effect of an analysis request triggered

  by the ANALYZE button, a special indicator bit is

  born by the program in the RAM When the next requested average of M heartbeats is formed, the programs for a mathematical definition of parameters

  characteristics in electrocardiogram signals from

  The number M must be high enough to obtain a statistically satisfactory average, but it must not be too large for the formation of the average does not take too much time, and a good choice corresponds to M = e, for example M = 16 The remaining functions of the analyzer, described above, are not interrupted, because they are ordered

  by clock 17 which interrupts the operation of the

  12 at regular time intervals and which commands the processor to perform the sampling, the input from the keyboard 14, the transfer of data to the printer 16

* or digital display devices, etc. As a result,

  the system works according to the principle of time

  in a manner determined by a functional part

  corresponding program recorded in the module of

moire 11.

  The average of the systoles treated by the analysis program must not be accessible for the introduction of new samples while the analysis is in progress. For this reason, there are two identical data interfaces which are in the random access memory. 10 and in which the average of M systoles is introduced alternately the results of the analysis are recorded in decimal code encoded in binary, in the form of a vector, in the random access memory 10 the output program combines these results with the texts saved in the memory module

  11 and it prints them in accordance with the protocol, by the printer

mantle 16.

  When the patient gets tired or if an abnormal reaction appears (a rhythm of beats or a pressure

  excessively high blood pressure), the effort must be stopped immediately

  The test is, so to speak, interrupted and this

  training is given to the analyzer by pressing the button

  INTERRUPTION by the operator At this moment, the value of

  The duration of the test is set to 0 (time measurement

  after the test), an analysis request is automatically generated

  and the results of the analysis are printed out, after which the minute and the second at which the test was interrupted are presented by means of the printer.

  On the other hand, it is necessary to hit on the keyboard 14 the cause of the interrup-

  tion and this information is also printed by the

  Thus, while the patient is recovering, all the functions of the analyzer become available and it is possible to re-analyze the input signal of the analyzer.

  trocardiogram at any time.

  when the STOP button is pressed, the device

  stops following the input signal, ie the clock

  programmed age 17 giving the sampling order stops.

  As a summary, the device prints through the printer 16 the total number of extra-systoles during

  the entire test, that is to say, the systoles of the type su-

  praventricular and ventricular type, the frequency of

  maximum allowable heart rate based on the age and sex of the patient, and the maximum frequency of

  beats that was actually achieved during the test.

  It is possible to introduce the keyboard 14 pressure

  maximum blood loss during the test If this is ef-

  the device calculates the product of this pressure by the maximum frequency reached for

  beats, and he also simultaneously prints out this

  divided by 1000 Among the printed information

  The data also include data on the theoretical value for oxygen consumption under effort, taking into account age, sex, weight and physical activity.

  of the patient, while the consumption that was actually

  can also be entered by the keyboard 14 or can be defined by the analyzer from the

duration of the test.

  the printer 16 finally traces histograms de-

  cut for variations in heart rate, the ratio of the R-wave during the effort to the P-wave before the effort, the J-point depression, the ST-segment slope and the integral corresponding to the area under the ST segment The system is then initialized automatically from

  how to be ready for the connection of a new patient.

  It goes without saying that many modifications can be made to the device described and shown without

depart from the scope of the invention.

Claims (3)

  Microcardiogram analyzer with microprocessor   connected to a recording device of   conventional type, characterized in that this recording device   The record is connected to the inputs of a multiple-circuit (6) whose input is also connected to the output   an interface (7) which is connected simultaneously to the   demultiplexer (8), while the output of the multi-   plexeur (6) is connected to the input of a low-pass filter (1) and the output of this filter (1) is connected to the input of circuits (2, 4) for eliminating disturbances related to sector, in which the output of the circuit (2) intended for the elimination of disturbances related to the sector   is connected to the input of the circuit (3) for eliminating   nation of disturbances related to the sector, the output of the latter is connected to the second input of the circuit (4) intended to eliminate disturbances related to the sector and the output of this latter circuit (4) is connected to   the input of a high-pass filter (5) whose output is   connected to the input of a 10-bit analog-to-digital converter (9), and the output of this converter (9) is connected on the one hand to the input of an output interface (7) and is connected on the other hand to an adapter of   peripherals (13) which is simultaneously connected to a   memory (10), to a memory module (11), to a micro-   8-bit processor (12) and a programmed clock (17), and the peripheral adapter (13) is connected to another   to an alphanumeric keyboard (14), to a device for   (15) and to a printer (16).   Analyzer according to Claim 1, characterized   in that the anode of a diode (D 20) is connected to the coil   a power transformer by the sector,   via an input (V 20), and the cathode of this   the diode is connected by a resistor (R 20) to the base of an NPN transistor (T 20), the emitter of which is connected to   mass, while the collector receives a voltage of   (+ VDD) via a resistor (Ra)   and this collector is simultaneously connected to one of the   trenches of a voltage controlled oscillator (21) whose output is connected to the input of a binary counter (22) whose outputs (I 20, 21 'I 22' I 23) are connected to the inputs of controlling analog switches (23, 24), the outputs of these switches (23, 24) are connected   to a capacitor framework (C 230 0246), the   very armatures are connected together and are connected at one end of a variable resistor (P 20) and at the input of a separator stage (25), the output of the separator stage is connected to the input of a low-pass filter (30) whose output is connected to the input of a high-pass filter (31), and the output of the high-pass filter is connected to the input of an adder (40) via a variable resistor (P 32), while the same input of the adder is connected by a resistor (R 40) to the other end of the variable resistor (P 20), as well as to a connector for the signal (V 21), and the output of the adder (40)   is connected to the input of the analog-to-digital converter (9).   Analyzer according to claim 1, wherein   the keyboard (14) is connected to the processor (12) and adapts   peripheral device (13) by a pulse generating circuit, characterized in that said circuit comprises diodes (D 140), D 141, D 142) and resistors (R 140, R 141,   R 142), in which the connection points between a diode   and an individual resistor form inputs (V 140, V 141, V 142) which are connected to three function buttons (ANALYSIS, INTERRUPTION, STOP) whose other terminals are connected to ground, the anodes of the diodes (D 140 , D 141, D 142) are connected together and are connected by a resistor (R 143) to the base of a PNP transistor (T 140) whose emitter is connected to a power supply terminal (Vcc) and   to an armature of a capacitor (C 140) whose other armature   re is connected to the base of this transistor (T 140), while   its collector is connected to the ground by a resistor   this CR 144) and at the clock input (Ci) of a bistable flip-flop   type D integrated circuit (IC 140), in which a   resistor (R 145) is connected between an input and an output   tie (R 1, Q 1), and, in addition, an armature of a capacitor   (a 141) is connected to said input (R 1) and the other arma-   this capacitor is connected to ground, while an output (Q 1) of the flip-flop is connected to the clock input (02) of a second flip-flop in the same integrated circuit (Io 0140), and an output (Z 2) of the second   flip-flop is connected to an input (D 1) of the first bass   cule, while another output (Q 2) of the second flip-flop   is connected to an input (R 2) of this flip-flop by the in-   via a resistor (R 146) on which a diode (D 143) is connected in parallel, and this input (R 2) is simultaneously connected to ground by a capacitor (0142) while an output (I 140) is connected to a point   connection (Q 02) which is connected to the processor (12).