So what exactly are those four thingies?

Discussion in 'Apple Watch' started by profmatt, Mar 12, 2015.

  1. profmatt macrumors 65816

    profmatt

    Joined:
    Mar 7, 2015
    Location:
    UK
    #1
    On the back of the watch, what exactly are those four thingies. Are they all just to measure heart-rate?
     
  2. nwlondonlad macrumors 6502a

    nwlondonlad

    Joined:
    Sep 20, 2007
    Location:
    UK London
    #2
    They are the sensors that will monitor heartbeat and other functions
     
  3. troop231 macrumors 603

    Joined:
    Jan 20, 2010
    #3
    Two are IR LEDs, and the other two are the actual optical sensors.
     
  4. profmatt thread starter macrumors 65816

    profmatt

    Joined:
    Mar 7, 2015
    Location:
    UK
    #4
    What other functions?
     
  5. nwlondonlad macrumors 6502a

    nwlondonlad

    Joined:
    Sep 20, 2007
    Location:
    UK London
    #5
    Movement via accelerometer and possibly gyroscope.
     
  6. omgitscro macrumors 6502a

    omgitscro

    Joined:
    Jul 12, 2008
    #6
    Accelerometers and gyroscopes are teeny-tiny components mounted on the PCB. What do the LEDs and light sensors have to do with this?
     
  7. Lennyvalentin macrumors 6502a

    Lennyvalentin

    Joined:
    Apr 25, 2011
    #7
    Each sensor window contains one set of LEDs and photodiodes; a pair of sensors use green visible light LEDs with matching photodiodes, the other pair uses infra-red LEDs.

    Your skin and flesh is too opaque for light from one sensor window to make it to another. These are extremely faint LEDs; a stamp-sized battery runs the entire watch in fitness mode for over six hours.
     
  8. Mascots macrumors 65816

    Mascots

    Joined:
    Sep 5, 2009
    #8
    While HR reading is the primary usage of that sensor, it has a few other use cases.

    For example, the sensor is responsible for determining if the Watch is in use to prevent notifications from firing when it's not on you.

    But as far as any extended functionality, that's about it. Just use cases for a sensor that acknowledges your presence and gives metrics on your heart.
     
  9. nwlondonlad macrumors 6502a

    nwlondonlad

    Joined:
    Sep 20, 2007
    Location:
    UK London
    #9
    Everything and nothing
     
  10. Appl3FTW macrumors 601

    Appl3FTW

    Joined:
    Nov 15, 2012

Share This Page