fig1 indicates a manikin 4 , to which electrodes 1 have been attached by an adhesive , in a manner that in itself is known . the electrodes 1 are directly connected to an aed / aed - t 3 . the purpose of the communication is to simulate the use of a real aed on a patient , by using the training equipment . this is done by communicating simulated physiological parameters and actions on the training equipment to the aed / aed - t , and by communicating the operation of the aed / aed - t to the training equipment . the following are examples of the type of information that may be exchanged : status / type of ecg , simulated ecg signal in real time , checking of unconsciousness , palpating pulse , free respiratory passages in the manikin after bending the head back and / or lifting the jaw , quality of hlr including depth / rate of compressions and rate / volume of ventilations , blowing - in time , hand positioning in the case of heart compression , synchronous or asynchronous pulse , medication - type , amount , time and place of injection , infusion - type , amount , time and place of infusion , electrode connection including electrode positioning , delivered electric shock , control of simulated muscle spasms at shock delivery , spontaneous breathing , chest movements , electric shock energy , spo 2 - value , end - tidal co 2 , blood pressure reading , all operating parameters of the aed and the training equipment , physiological body sounds , automatic switching of the training equipment between on and off , and automatic switching of the aed between on and off . it is envisaged that the communication will take place primarily over electrodes that are glued or otherwise attached to the chest of the manikin , the skin of which is made from a non - conductive material , so that all communication can be wireless and take place between the electrodes and the sensors in the training equipment ; or there may be direct wireless communication between the training equipment and the aed / aed - t independently of the electrodes , where the electrodes transmit a signal in the form of a signature that indicates contact between the sensors and the electrodes , and which initiates another direct , wireless communication . both special training electrodes and treatment electrodes may be used . these are connected to the aed / aed - t 3 by means of a cable , and are glued or otherwise attached to the manikin &# 39 ; s 4 chest . sensors 2 are placed on the underside of the manikin &# 39 ; s 4 chest , in order to measure the positioning of the electrodes 1 and communicate wirelessly with the electrodes 1 . this can be implemented through a capacity coupling , in which the electrode 1 acts as one disc of a capacitor and the sensor 2 acts as the other disc , see fig2 . it may also be solved by the use of inductance , where the sensor 2 in the manikin is a coil with one or more turns . the electrode 1 can also be designed as a coil for use in communication , or it may be a metallic foil , see fig3 . the electrode 1 may also act as a connection between several coils 2 placed in or on the inside of the skin on the manikin &# 39 ; s 5 chest . ( fig4 ). in order to measure the positioning of the electrodes , the electrode 1 and the sensor 2 may be constructed with only one connecting element , see the examples in fig2 and fig3 . here , it will be possible to measure the degree of connection between the electrode 1 and the sensor 2 , and then to determine an approximate electrode positioning based on this . such a measurement is known in itself , and those skilled in the art will know how to implement it . fig5 schematically shows an example where the electrode 1 and the sensor 2 are constructed with several connecting elements . here , it will be possible both to measure the degree of connection between the electrode 1 and the sensor 2 , and determine the exact positioning of the electrode . a solution may also be envisaged where the entire chest skin is a matrix of sensors , see fig6 . it will then be possible to determine electrode positions across the entire area of the chest . a sensor 2 may consist of two concentric faces , which do not overlap each other , see fig7 . these faces are connected to respective oscillators 8 that emit two different frequencies . when the aed by means of band - pass filters 6 and amplifiers 7 detects one of these frequencies on one electrode , it will automatically go into training mode . the ratio between the signal strength from the amplifiers 7 after the band - pass filters 6 will give information regarding electrode positioning . a solution may also be envisaged where these methods are used for measuring the position of the electrodes only , and where all communication between the manikin and the aed takes place through a wireless medium , across another interface . this may be in the form of radio communication , where for example the electrode cables are used as an antenna . other antenna solutions may also be envisaged . alternatively , other forms of communication may be used , such as light , primarily in the form of ir light , or sound , primarily in the form of ultrasound . any form of analog or digital modulation may be used for wireless communication , e . g ., fm , am , cw , bpsk ( binary phase shift keying ), qpsk ( quadrature phase shift keying ), fsk ( frequency shift keying ), m - fsk ( m - ary frequency shift keying ). the receiver in the aed may in its simplest form use the ecg amplifier as a receiver for the signals from the manikin . the ecg amplifier may have several modes of operation , in which it changes the frequency characteristics when in training mode , so as to be able to transmit relatively high frequency signals . the transmitter in the aed may in its simplest form consist of a shock delivery circuit with several modes of operation , in which it delivers harmless and electrically safe micropulses when in training mode . known systems for measuring impedance and systems for connecting electrodes may also be used as a transmitter in the aed . these systems are normally based on a low alternating current being sent through the patient electrodes . obviously , the ac - current may also be used to communicate with the manikin , in a modulated or non - modulated form . aeds often use relay connections for delivering electroshocks . switching this relay connection on and off will cause a change in impedance in the aed patient circuit . this change in impedance may also be used for communication between the aed and the manikin . the transmitter and the receiver may also be realized as circuit solutions that are independent of the ecg amplifier , the shock delivery circuit and the systems for measuring impedance . in a preferred embodiment , the training equipment a is provided with a microprocessor 9 with an algorithm for generating a partial response type modulated signal . following a digital to analog conversion 11 , this signal is transmitted to respective drivers , in order to drive the signal symmetrically for each of the sensors 2 in the training equipment a . these sensors 2 are attached to the inside of a non - conductive chest skin 5 , and each of the sensors form half of a capacitor , in which the chest skin 5 of the training equipment 5 forms the insulation between the capacitor discs . the electrodes 1 belonging to a defibrillator ( aed ) or a defibrillator - trainer ( aed - t ) form the other half of the capacitor discs . if the equipment that is connected up is an aed , the existing ecg inlet 15 or inlet for impedance measurement signal 15 is used as a receiver for the communication signal . if the equipment that is connected up is an aed - t , the electrodes 1 will be connected to a signal meter 15 , which is further connected to an analog - digital converter 16 , and thereafter to a microprocessor 17 , in which the signal is demodulated . as use of the training equipment will result in movement between the electrodes 1 and the sensors 2 , and thereby in variable capacitance , a current meter 12 , 14 has been put in the training equipment a , which meter transmits a signal to the microprocessor 9 ( not shown ). the electric signal uses the microprocessor 9 to control the biasing , to ensure that the communication signal maintains approximately equal strength between the electrodes 1 . each of the sensors in the manikin consists of a flexible , electrically conductive area , with a diameter of 5 - 15 cm . around each sensor is another electrically conductive area . these areas have been positioned to form the non - valid areas of electrode positioning . a signal with a fixed signature s 2 or frequency f 2 is transmitted to these areas , whereas a signal with a fixed signature s 1 or frequency f 1 is transmitted to each sensor . correct placing of the electrodes is determined according to the ratio between s 1 and s 2 or according to the ratio between f 1 and f 2 , and this can be measured both by the current meter 12 , 14 in the training equipment a and by the signal meter in the ecg measuring system in the aed b . in order to indicate the correct placement of the electrodes , a light source 20 ( fig7 ) has been provided in the center of each sensor . this is not normally visible or noticeable . when the light source lights up , it will shine through the chest skin when this is made of pp , pe , tpe , pvc or silicone materials and the thickness is 1 mm - 6 mm . the communication signal from the aed to the training equipment is the signal belonging to the system , which is measuring the impedance 18 , modulated from the microprocessor 17 in the aed . from an aed - t , this signal will consist of a modulated signal with a basic frequency of between 500 hz and 500 khz . the communication signal is transmitted capacitively from the electrodes to the sensors in the training equipment . the signal meter 13 in the training equipment will transmit the signal to an analog - digital converter 10 , from which the signal goes to the microprocessor for demodulation .
a system for communication between sensors in training equipment and electrodes for a defibrillator or a defibrillator - trainer provides for determining electrode positioning and providing feedback to the user . the training equipment is provided with a non - conductive chest skin , and the communication is wireless and bi - directional . the information from the manikin is generated by a microprocessor with a digital - analog converter . the information signal is transmitted to the sensors in the manikin by use of drivers , which sensors each constitute one half of a non - galvanic coupling , in which the chest skin separates the halves , and the other halves of the non - galvanic couplings are formed by electrodes that are attached to the chest skin , the non - galvanic coupling being in the form of capacitors or coils .