Accelometer reading difference in iPhone 3GS, iPod 5 and iPhone 4

Discussion in 'iOS 5 and earlier' started by RaoNawaz, Mar 12, 2013.

  1. RaoNawaz macrumors newbie

    Mar 12, 2013
    Are the accelerometers in older iPhone/iPad/iPod models comparable to current models in terms of sensitivity/accuracy (such that no perceivable difference in readings)?

    For example, if someone takes accelerometer readings on their iPhone 3GS, and I take readings with an iPhone 4S, and someone else does it with an iPad, assuming all else equal, will we get similar results? What kind of deviation would one see? For example, let's say you put all the devices on a table that is vibrating enough to show up on an accelerometer. Would different device versions show results within the same level of accuracy? What are the limitations? I know that the older iPhones have an older version of the accelerometer, and although I found their datasheets, I could not tell whether the differences were significant.

    Of course I can do an experiment to determine if their are perceivable differences in my application, but I was wondering if anyone had prior experience with this.
  2. Menge macrumors 6502a


    Dec 22, 2008
    I think the difference is small enough that you shouldn't consider its existence. But keep in mind that the accelerometer readings are extremely volatile. Any movement and it flickers (which is why you should apply a low-pass filter to the input).

    The readings are measured in Gs, so they should all read the same value if positioned exactly the same :)
  3. moonman239 macrumors 68000

    Mar 27, 2009
    I'm sure any difference in readings would be small. However, the iPhone 4, 4S, and 5 all have gyroscopes. Gyroscopes measure the acceleration caused by motion. For the 3GS, you'll need to apply a low-pass filter.
  4. RaoNawaz thread starter macrumors newbie

    Mar 12, 2013
    Accelerometer reading difference.

    I am experiencing major difference to me. Whenever i accelerate devices in same direction and probably with same shake effect ,It gives me different readings for difference devices.

    I am mostly getting

    iphone 4 and ipod 4 : 1.934708, 1.592178, -1.945648
    For iPod 5 : 3.12010, 1.104568, -1.294567

    keeping shake effect and direction same.
    I am using absolute values.
    I dont know why such huge difference.

Share This Page