Patent Abstract:
A system for monitoring animate presence, including one or more ultrasonic transducers configured to transmit an ultrasonic signal, one or more ultrasonic receivers configured to receive an echo signal in response to the transmitted ultrasonic signal, an electronic circuit for comparing the transmitted signal to the received echo signal and identify a phase shift between the signals; wherein the electronic circuit identifies animate presence based on the identified phase shift.

Full Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to automatic detection and/or monitoring of animate presence using an ultrasonic system. 
       BACKGROUND 
       [0002]    Ultrasonic transducers are sensors that convert ultrasound waves to electrical signals and electrical signals to ultrasound waves. Ultrasonic transducers that both transmit and receive are sometimes referred to as ultrasonic transceivers. Ultrasonic transducers are commonly used like radar and sonar systems to detect a target based on the response to a transmitted ultrasonic signal, for example by comparing the time interval between sending the signal and receiving an echo to determine the distance to an object or if it is in motion. Ultrasonic transducers are commonly used in cars as parking sensors to help direct the driver in reversing into a parking space. 
         [0003]    In many cases it is of interest to keep track of living people or animals, for example to make sure that they are confined to a specific area or that they are alone in the area. Additionally it may be of interest to verify that they are alive. 
         [0004]    In contrast in some cases it may be of interest to negate animate presence, for example to make sure that people or animals do not enter a specific area (e.g. a room) or do not come near a specific object, animal or person. Generally these objectives can be achieved by placing a guard or caretaker to watch the person, animal or object. However it would be desirable to automate this task, to reduce the need to invest in manpower. 
         [0005]    An ultrasonic transducer could be used to detect the presence of a person, for example based on motion. However such systems do not differentiate between animate objects and inanimate objects. 
       SUMMARY 
       [0006]    An aspect of an embodiment of the disclosure relates to a system and method of detecting and/or monitoring animate presence in the vicinity of the system. The system includes one or more ultrasonic transducers, receivers and an electronic circuit to analyze the measurements. The electronic circuit analyzes the signals transmitted by the transducers relative to the echo signals received by the receivers in response to identify a phase shift between the signals, the phase shifts provides indication of animate presence, for example a live person or live animal. The system provides notification to a user based on the results of the analysis. Optionally, the system differentiates between a single detected live person or animal and multiple people and/or animals. In some embodiments of the disclosure, the system can identify if the animate presence is from a grown up person, child, infant or specific types of animals. 
         [0007]    There is thus provided according to an exemplary embodiment of the disclosure, a system for monitoring animate presence, comprising: 
         [0008]    One or more ultrasonic transducers configured to transmit an ultrasonic signal; 
         [0009]    One or more ultrasonic receivers configured to receive an echo signal in response to the transmitted ultrasonic signal; 
         [0010]    An electronic circuit for comparing the transmitted signal to the received echo signal and identify a phase shift between the signals; wherein the electronic circuit identifies animate presence based on the identified phase shift. 
         [0011]    In an exemplary embodiment of the disclosure, the electronic circuit is configured to differentiate between a single animate entity and multiple animate entities. Optionally, the electronic circuit is configured to differentiate between people and animals. In an exemplary embodiment of the disclosure, the electronic circuit is configured to send notification if more than one person is detected in a monitored room. Optionally, the electronic circuit is configured to monitor a Wi-Fi connection and provide a notification if the Wi-Fi connection is unavailable and there exists animate presence. 
         [0012]    In an exemplary embodiment of the disclosure, the electronic circuit is configured to monitor the respiratory activity of an observed individual and activate an alarm if the respiratory activity ceases or is abnormal. Optionally, the electronic circuit is configured to monitor animate presence in a closed area and activate an alarm if no animate presence is detected or more than one organism is detected. In an exemplary embodiment of the disclosure, the system includes a communication unit for providing results with a wireless electromagnetic signal. Optionally, the system is configured to monitor animate presence in a room and provide the results to a user in a different room. In an exemplary embodiment of the disclosure, the system is shaped as a sphere to monitor in substantially any direction. 
         [0013]    There is further provided according to an exemplary embodiment of the disclosure, a method of monitoring animate presence, comprising: 
         [0014]    Transmitting an ultrasonic signal with one or more ultrasonic transducers; receiving an echo signal in response to the transmitted ultrasonic signal by one or more ultrasonic receivers; 
         [0015]    Comparing the transmitted signal to the received echo signal using an electronic circuit to identify a phase shift between the signals; and 
         [0016]    Identifying animate presence based on the identified phase shift. 
         [0017]    In an exemplary embodiment of the disclosure, the electronic circuit is configured to differentiate between a single animate entity and multiple animate entities. Optionally, the electronic circuit is configured to differentiate between people and animals. In an exemplary embodiment of the disclosure, the electronic circuit is configured to send notification if more than one person is detected in a monitored room. In an exemplary embodiment of the disclosure, the electronic circuit is configured to monitor a Wi-Fi connection and provide a notification if the Wi-Fi connection is unavailable and there exists animate presence. Optionally, the electronic circuit is configured to monitor the respiratory activity of an observed individual and activate an alarm if the respiratory activity ceases or is abnormal. In an exemplary embodiment of the disclosure, the electronic circuit is configured to monitor animate presence in a closed area and activate an alarm if no animate presence is detected or more than one organism is detected. Optionally, results of the identifying are provided by an electromagnetic signal. In an exemplary embodiment of the disclosure, the monitoring is performed in a room and results are provided to a user in a different room. In an exemplary embodiment of the disclosure, the system is shaped as a sphere to monitor in substantially any direction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The present disclosure will be understood and better appreciated from the following detailed description taken in conjunction with the drawings. Identical structures, elements or parts, which appear in more than one figure, are generally labeled with the same or similar number in all the figures in which they appear. It should be noted that the elements or parts in the figures are not necessarily shown to scale, each element or part may be larger or smaller than actually shown. 
           [0019]      FIG. 1  is a schematic illustration of a system for detecting animate presence, according to an exemplary embodiment of the disclosure; 
           [0020]      FIG. 2A  is a graph of a recorded echo signal in time domain, according to an exemplary embodiment of the disclosure; 
           [0021]      FIG. 2B  is a graph of a recorded echo signal in frequency domain, according to an exemplary embodiment of the disclosure; 
           [0022]      FIG. 3A  is a schematic illustration of a system for monitoring animate presence in a room, according to an exemplary embodiment of the disclosure; 
           [0023]      FIG. 3B  is a flow diagram of a method of monitoring animate presence in a room, according to an exemplary embodiment of the disclosure; 
           [0024]      FIG. 4A  is a schematic illustration of a system for monitoring animate presence in a vehicle, according to an exemplary embodiment of the disclosure; 
           [0025]      FIG. 4B  is a flow diagram of a method of monitoring animate presence in a vehicle, according to an exemplary embodiment of the disclosure; 
           [0026]      FIG. 5A  is a schematic illustration of a system for monitoring respiratory activity of an infant, according to an exemplary embodiment of the disclosure; 
           [0027]      FIG. 5B  is a flow diagram of a method of monitoring respiratory activity of an infant, according to an exemplary embodiment of the disclosure; 
           [0028]      FIG. 6A  is a schematic illustration of a system for guarding an animal, according to an exemplary embodiment of the disclosure; 
           [0029]      FIG. 6B  is a flow diagram of a method of guarding an animal, according to an exemplary embodiment of the disclosure; 
           [0030]      FIG. 7A  is a schematic illustration of a personal alarm system, according to an exemplary embodiment of the disclosure; 
           [0031]      FIG. 7B  is a flow diagram of a personal alarm system, according to an exemplary embodiment of the disclosure; 
           [0032]      FIG. 8A  is a schematic illustration of a preview security system, according to an exemplary embodiment of the disclosure; and 
           [0033]      FIG. 8B  is a flow diagram of a preview security system, according to an exemplary embodiment of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]      FIG. 1  is a schematic illustration of a system  100  for detecting animate presence, according to an exemplary embodiment of the disclosure. In an exemplary embodiment of the disclosure, system  100  uses one or more ultrasonic transducers  110  and one or more ultrasonic receivers  120  to monitor activity in the vicinity of the system  100 . System  100  transmits a sound wave signal  115  having a frequency in the range of 18 KHz to 1 GHz to enable a reasonable detection range (higher frequencies have a lower detection range). In an exemplary embodiment of the disclosure, the transmitted signal comprises a train of pulses having the selected frequency (for example 10 pulses per second). Receiver  120  records an echo signal  125  resulting from the transmitted sound wave signal  115  being reflected off animate and/or inanimate objects, for example a person or wall. The recorded echo signal  125  is compared to the transmitted signal  115  pulse by pulse. Optionally, an echo signal  125  from animate objects will have a phase shift due to the respiratory system of the person or animal in contrast to the echo signal  125  from inanimate objects that will maintain its phase, for example adult breathing can cause a phase shift having a frequency of about 0.3 Hz and an infant can cause a phase shift having a frequency of about 0.1 Hz. Likewise the heartbeat of an adult can cause a phase shift having a frequency of about 1.2 Hz and an infant can cause a phase shift having a frequency of about 2 Hz. Accordingly by measuring the signal propagation time, signal amplitude and phase shift one can determine the distance to an object and if it is animate or inanimate. Optionally, system  100  is pre-programmed with an empirical list of phase shift ranges for people of different ages (e.g. infants, children and grown-ups) and/or different types and ages of animals (e.g. horses, dogs, cats, bears, tigers, lions, donkeys and other animals). The empirical list is formed by measuring the phase shift resulting from sound wave signal  115  propagating through air (with a velocity of about 300 meters per second) toward various live targets at different distances (e.g. 1-10 meters). In an exemplary embodiment of the disclosure, system  100  can differentiate between people and animals and different type of animals and/or different ages/groups. Optionally, system  100  can differentiate between a single person and multiple people, for example between 2 people and 3 people, or more people. 
         [0035]    In an exemplary embodiment of the disclosure, system  100  includes an electronic circuit  105  coupled to the transducers  110  and/or receivers  120 , the electronic circuit including one or more of the following units: 
         [0036]    1. A signal generator  130  to produce a continuous wave signal with a desired frequency (e.g. between 20-200 KHz). Optionally, the wave form is a sine wave or square wave or other form of wave. 
         [0037]    2. A pulse modulator  140  that receives the signal from the signal generator  130  and modulates it to form a train of pulses, for example about 10 pulses a second having the desired frequency. Optionally, each pulse is selected to have a duration of about 1 millisecond thus providing a detection discrimination resolution of about 15 cm. 
         [0038]    3. A power amplifier  150  that receives pulses from modulator  140  and amplifies them for transmission with transducers  110 . 
         [0039]    4. A detection synchronization unit  160  that is gated with the pulse modulator  140  to synchronize the pulses of the received echo signal  125  with the pulses of the transmitted signal  115 . 
         [0040]    5. A phase detector  170  that receives the echo signal  125  from the receiver  120  and provides an output signal  175  representing the phase shift identified between the echo signal  125  and the wave signal provided by the pulse generator  130 . 
         [0041]    6. A microprocessor  180  that receives output signal  175  and processes the signal. Optionally, the signal processing removes noise (e.g. FFT, noise reduction) and determines if the phase signal indicates the presence of one or more live people, animal&#39;s or inanimate objects. 
         [0042]    In an exemplary embodiment of the disclosure, the electronic circuit  105  may include an onboard display  190  or may be connected to an external display e.g. a standard computer display. The display will provide indications to a user regarding the findings of system  100 . Alternatively or additionally, electronic circuit  105  is connected to a communication unit  195 , for example a Wi-Fi connector, Blue-Tooth connector, Cellular Mobile transmitter, wired link, RF transmitter, an audible alarm or audio-visual alarm to communicate with other computers, networks and/or people. Optionally, the communication unit  195  is used to notify a user, provide an alert or request action. 
         [0043]    In an exemplary embodiment of the disclosure, system  100  receives power from a standard domestic power socket (e.g. 110V or 220V). Alternatively or additionally, system  100  may be battery powered so that it is protected against power outage and is independent of a power source at least for a specific duration. Optionally, the battery can be chargeable or replaceable. 
         [0044]      FIG. 2A  is a graph  200  of the recorded echo signal  125  in time domain and  FIG. 2B  is a graph  250  of the recorded echo signal  125  in frequency domain, according to an exemplary embodiment of the disclosure. Optionally, graph  200  depicts multiple overlapping pulses of the recorded echo signal  125 . In most positions the multiple pulses are essentially the same and in specific positions (e.g. affected by animate breathing or heartbeats) the multiple pulses differ. In an exemplary embodiment of the disclosure, the graphs ( 200 ,  250 ) are affected by the presence of two people with distinct heart beats and breathing rates that affect the recorded echo signal  125 . Transforming the raw signal as depicted in graph  200  to the frequency domain as depicted in graph  250  helps to enhance detection of the presence of the two people.  FIGS. 2A and 2B  represent a 10 Hz repetitive pulse with the first person having a breathing rate causing a phase shift of 0.3 Hz and a heartbeat causing a phase shift of 1 Hz. The second person is shown to have a breathing rate causing a phase shift of 0.4 Hz and a heartbeat causing a phase shift of 1.2 Hz. 
         [0045]    In an exemplary embodiment of the disclosure, system  100  can be used to monitor a student taking an exam in a room, wherein system  100  is used to ensure that the student works alone (e.g. during a test) without other people in the vicinity. Optionally, system  100  can be set to use a basic signal frequency of about 40 KHz to provide a detection range of about 4 meters. 
         [0046]      FIG. 3A  is a schematic illustration of a system  300  for monitoring a room for animate presence, and  FIG. 3B  is a flow diagram  310  of a method of monitoring a room for animate presence, according to an exemplary embodiment of the disclosure. In an exemplary embodiment of the disclosure, system  300  is designed to include electronic circuit  105  with multiple transducers  110  and multiple receivers  120 . Optionally, the transducers  110  and receivers  120  are configured to cover 360 degrees around system  300 , wherein each transducer may sample for example a meter wide (e.g. up and down) thus essentially sampling a disk shaped area of the entire room surrounding system  300 . 
         [0047]    In an exemplary embodiment of the disclosure, system  300  is designed to monitor a room and identify if a single person is present or if there are additional people. If the number of people is greater than one an event is recorded and notification may be sent to an administrator. In the flow diagram  310  P denotes the number of attempts to detect animate presence before declaring an error, and V denotes the number of times more than one person can be detected that are allowed to be identified before sending notification to the administrator. 
         [0048]    In an exemplary embodiment of the disclosure, P and V are initially set to zero  312 . System  300  monitors the room and searches for animate presence  314 . Optionally, if no animate presence is detected system  300  keeps waiting or may provide an alert after a time limit defined by P. If animate presence is detected then if more than one person is detected  318  then V is incremented and system  300  continues to check after a preselected time delay  316  if the extra people left the room and only one person remains, for example a person may be allowed to enter the room for a short period to provide test papers to the student. If more than one person is detected again and again, V is incremented and after a pre-selected number of time delays (m) notification is sent  320  to the administrator to take actions. 
         [0049]    In an exemplary embodiment of the disclosure, system  300  may be used to monitor a person taking a test at home. Optionally, the person is required to isolate himself in a room and activate system  300  at the beginning of the test. If the presence of other people is detected the test can be invalidated. 
         [0050]      FIG. 4A  is a schematic illustration of a system  400  for monitoring animate presence in a vehicle  405  and  FIG. 4B  is a flow diagram  460  of a method of monitoring animate presence in the vehicle  405 , according to an exemplary embodiment of the disclosure. In an exemplary embodiment of the disclosure, system  400  is installed in vehicle  405 , for example by using an attachment means  450  (e.g. a vacuum rubber with a rod) to attach it to a window or roof of the vehicle  405 . Optionally, the system  400  includes one or more transducers  110  and receivers  120  to monitor an angle of about 60-90 degrees to detect animate presence in the vehicle  405 , for example an infant  415  in the front seat or back seat of the vehicle  405 . Alternatively or additionally, in a large vehicle  405  (e.g. a bus or truck) the system  400  may be installed in the center of the vehicle with detection ability of about 180 degrees or even 360 degrees. Optionally, system  400  is powered from the cigarette lighter socket  440  by a cable  430  or directly hardwired to the vehicle electronic system. 
         [0051]    In an exemplary embodiment of the disclosure, system  400  supports cellular communications with a sim card  420  in communication unit  195  to notify a pre-programmed telephone in case a determination is made that a monitored person  415  (e.g. infant or handicapped person) is left unattended in the vehicle  405  for more than a pre-selected time. As shown in  FIG. 4B  the user (e.g. the vehicle driver) initializes a mobile application  462  that provides local Wi-Fi communications to system  400 . Additionally, the user turns on system  400 . System  400  checks  464  if there exists Wi-Fi communication with the application on the user&#39;s mobile device. If yes system  400  starts monitoring  466  the vehicle (e.g. a specific seat or area that system  400  is aimed at). Optionally, system  400  provides notification (e.g. a LED or audio signal) that it has started to monitor, so that if it fails to start the user is notified that an error has occurred and can troubleshoot the system  400 , for example check if the application is active on his/her mobile device or check for other errors. In an exemplary embodiment of the disclosure, system  400  initially checks for animate presence  468  for monitoring. If animate presence is detected (e.g. an infant in the monitored area of the vehicle), then system  400  checks for the presence of Wi-Fi communication  470  from the user&#39;s mobile device. As long as Wi-Fi communication is available and the animate presence is there system  400  keeps monitoring. However if Wi-Fi communication is lost for a pre-selected time (e.g. because the driver left the vehicle) but animate presence remains then system  400  will activate an alarm  472 , for example by calling the user and/or other pre-programmed entities (e.g. father, mother, other relatives or calling center) over a cellular network (e.g. using sim card  420 ) and provide notification that the monitored person  415  is left unattended in the vehicle. 
         [0052]      FIG. 5A  is a schematic illustration of a system  500  for monitoring respiratory activity of an infant  510  and  FIG. 5B  is a flow diagram  560  of a method of monitoring respiratory activity of an infant  510 , according to an exemplary embodiment of the disclosure. In an exemplary embodiment of the disclosure, system  500  is placed near the body or face of the infant  510 , for example on a side of a crib  520 . System  500  is equipped with one or more ultrasonic transducers  110  and one or more ultrasonic receivers  120  that are arranged, for example with a dispersion angle of between 50 to 70 degrees since in general an infant using system  500  does not move much. Optionally, a frequency of about 200 KHz instead of about 40 KHz can be used to improve detection resolution, since the measured distance is small (e.g. about 1 meter). 
         [0053]    In an exemplary embodiment of the disclosure, system  500  is powered on  565  after putting the infant  510  in the crib  520 . Then system  500  detects breathing  570  of the infant  510 . If no breathing is detected an indication of an error  575  is provided by system  500  otherwise system  500  verifies  580  that the breathing is in the normal range for an infant, for example forming a phase shift of less than 0.6 Hz. If the breathing is normal system  500  continues to monitor the infant  510 . Otherwise if the breathing ceases or is abnormal system  500  activates an alarm  590  that uses communication unit  195  to communicate with a remote receiver  530  that is located, for example with the mother  535  or father. Optionally, the remote receiver  530  may be communicated by an RF signal or over a Wi-Fi network. In some embodiments of the disclosure, the remote receiver may be a mobile telephone that is contacted by system  500  having a sim card in communication unit  195 . In some embodiments of the disclosure, communication unit  195  is connected by a cable to remote receiver  530 . 
         [0054]      FIG. 6A  is a schematic illustration of a system  600  for guarding an animal and  FIG. 6B  is a flow diagram  660  of a method of guarding an animal  610 , according to an exemplary embodiment of the disclosure. Some animals are expensive and it desirable to have them monitored to prevent theft, for example purebred horses. In an exemplary embodiment of the disclosure, system  600  monitors the animal and notifies a caretaker if anybody comes near the animal  610  or if another animal is placed near the animal  610 . Optionally, system  600  includes one or more ultrasonic transducers  110  and one or more ultrasonic receivers  120 . Optionally, the transducers  110  and receivers  120  are arranged to monitor an angle of between 120 to 180 degrees to cover an entire closed area such as a stable or stall. 
         [0055]    In an exemplary embodiment of the disclosure, system  600  is powered on  665  and attempts to detect  670  the animal  610 . If no animal is detected an error indication  690  will be produced so that the user can fix the error so that system  600  can function properly. If the animal  610  is detected the system  600  starts to monitor  675  the animal  610 . Optionally, system  600  continuously detects animate presence  680 . If animate presence is not detected an alarm  695  is activated. Optionally, the alarm uses communication unit  195  to notify the caretaker that security has been breached. Communication may be realized in the form of a sim card communicating over a cellular network or by a local Internet connection (e.g. Wi-Fi). Optionally, a vocal message may be transferred or a text message (e.g. SMS or other applications). If animate presence is detected, system  600  checks if more than one organism was detected  685 , for example if another animal or person enters the closed area. If only a single organism was detected system  600  continues to monitor the animal  610 . Otherwise system  600  activates an alarm to notify the caretaker. 
         [0056]      FIG. 7A  is a schematic illustration of a personal alarm system  700  and  FIG. 7B  is a flow diagram  760  of personal alarm system  700 , according to an exemplary embodiment of the disclosure. The personal alarm system can be used in a room in which a person  710  is situated alone and warn the person  710  if someone else enters the room, for example when the person  710  is asleep in a hotel room the person can be protected from thieves while sleeping. In some embodiments of the disclosure, personal alarm system  700  can be used to protect more than one person, for example 2, 3 or 4 people. In an exemplary embodiment of the disclosure, personal alarm system  700  may be placed at one side of the room to monitor the room with one or more ultrasonic transducers  110  and one or more ultrasonic receivers  120 . Optionally, the transducers  110  and receivers  120  are configured to cover 120 to 180 degrees around personal alarm system  700  to cover all of the room or at least covering the person and entrances to the room. 
         [0057]    In an exemplary embodiment of the disclosure, the user powers on  765  the personal alarm system  700  for it to start monitoring. Personal alarm system  700  begins by detecting animate presence  770  (the person  710 ) and providing an indication (e.g. a LED) that it is functioning. The personal alarm system  700  starts monitoring the room  775 . While monitoring the personal alarm system  700  detects animate presence  780  and then determines if it detected a single person or more  785 . If only a single person was detected the personal alarm system continues to monitor the room. Otherwise if no animate presence is detected the personal alarm system provides an error indication  795 . Likewise if personal alarm system  700  detects more than one person it activates an alarm  790  to warn the person or other people (e.g. body guards that are located in another room). Optionally, personal alarm system  700  includes communication unit  195  that calls or sends a message to the other people and/or personal alarm system  700  may provide an indication in the form of an audible tone to wake up the person  710 , scare an intruder or summons help. 
         [0058]      FIG. 8A  is a schematic illustration of a preview security system  800 , and  FIG. 8B  is a flow diagram  860  of preview security system  800 , according to an exemplary embodiment of the disclosure. In many cases it is desirable to be able to know if there are people or animals around the corner or in a room without actually going there. In an exemplary embodiment of the disclosure, preview security system is designed as a ball that can be tossed into the room, around the corner or into a cave or other places to check if there is animate presence before entering. Optionally, preview security system includes ultrasonic transducers  110  and ultrasonic receivers  120  at various locations on the surface of the ball, so that preview security system  800  can monitor in substantially any direction. In an exemplary embodiment of the disclosure, the preview security system includes electronic circuit  105  for analyzing the measurements of the ultrasonic transducers  110  and ultrasonic receivers  120 . The results of the analysis are then transmitted wirelessly via communication unit  195  to a remote receiver  830 . Optionally, the communications may be transmitted using an RF signal or other types of wireless communications. 
         [0059]    In an exemplary embodiment of the disclosure, preview security system  800  is powered on  865  by the user. Then it is tossed  870  into the room (e.g. through a window), into a cave, over a fence, around a wall or into any place that is of interest to check. Optionally, preview security system  800  starts monitoring  875  by measuring and analyzing the measurements to determine if there is animate presence  880  in the vicinity of the preview security system  800 . Optionally the preview security system  800  then transmits wirelessly to remote device  830  an indication if it detected the existence of animate presence  895  or the absence of animate presence  890  so that the user may respond accordingly. 
         [0060]    It should further be appreciated that the above described methods and apparatus may be varied in many ways, including omitting or adding steps, changing the order of steps and the type of devices used. It should be appreciated that different features may be combined in different ways. In particular, not all the features shown above in a particular embodiment are necessary in every embodiment of the disclosure. Further combinations of the above features are also considered to be within the scope of some embodiments of the disclosure. It will also be appreciated by persons skilled in the art that the present disclosure is not limited to what has been particularly shown and described hereinabove.

Technology Classification (CPC): 6