GSMArena feature labs: The tests

26 April 2012
The GSMArena Labs are tests designed to give an objective account of how a device performs in real-world scenarios. In short, it's about what you can expect from a gadget you're planning to buy. Our tests are constantly being developed...

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  • M
  • Max
  • Mvv
  • 26 Apr 2012

Excellent article, thanks GSMArena for doing all these test for us all; they do help a lot. None of the following is in contradiction with the article, it's just a few additional points / clarifications I'd like to make:

- Display contrast test keep speaking about "black" levels. While entirely correct, this may create the impression that contrast only matters between "white" and "black" parts of a picture, which would fail to take into account that all colors on any display today are composed of distinct red, green and blue light emitters. Thus, for all fairly "pure" colors (mostly just red, just blue or just green) the two "unused" sub-pixels need to stay as "black" as possible for a vibrant result - therefore contrast is quite important even in a picture that has no obvious black parts at all.

- Acoustics are measured in decibels (ie. on a non-linear, logarithmic scale) for a good reason - because that's the scale human ears work on, too. Therefore while it is absolutely true that a 3db difference equals double the sound intensity (and a 6db one equals double the sound pressure) in a physical sense, you need a difference of TEN decibels to double the sound volume as perceived by the human ear [1]. A few dbs therefore take a lot more energy to generate but do not sound a lot louder.

- Stereo crosstalk is sound in a channel "bleeding over" from another channel, and the less of it you have the better. However, it's important to remember that zero decibel is an arbitrary level of sound intensity (about the typical threshold of hearing of an average human) and since crosstalk is very small usually, amounting to very quiet sound levels, it gets expressed as NEGATIVE decibels. Therefore, the less crosstalk there is, the bigger the db number will get, but in a negative direction (-50db crosstalk is much better than -30db). The original 'The larger this value is "the further away from zero"' is meant as "further away from zero in a negative sense", not as "larger in a mathematical sense, where -5 is a larger number than -50 is".

- Everybody knows that displaying remaining battery in most portable devices today is closer to predicting weather than factual appraisal. What not everybody may realise though is that in fact there is no direct way of telling how much energy is left in a cell. An ideal battery would keep its voltage perfectly constant - for any load - until it becomes empty, and absoultely noone could tell how much juice is left in it without taking it apart and analysing it chemically. The only reason we CAN (somewhat) tell what is in there is because cells are not perfect, and their voltage keeps dropping slightly as they discharge - emphasis on slightly. This small change is what devices are trying to detect - but considering that the change is small, dependes on the momentary load, the age of the cell and the way it has been used, the ambient temperature, and just possibly the alignment ocf the stars (just kidding), it becomes understandable that pretty much every portable device suck at telling how much energy it has left. The point where this becomes regrettable however is that these devices use the same measurement to decide they have too little energy left at some point, and switch off - possibly when there would still be quite a bit of juice in the batteries if only they would keep going. Which explains also why apparent battery capacity can depend on the firmware version of the device - even if said firmware does exactly nothing to reduce consumption, it might measure / display the battery levels differently.

[1] http://www.sengpielaudio.com/TableOfSoundPressureLevels.htm

    • ?
    • Anonymous
    • Mf5
    • 26 Apr 2012

    This is a really good idea for the tests for the phones, and it really gives a clear idea on how they perform....AWESOME JOB!

      • F
      • Fayez
      • 6Qq
      • 25 Apr 2012

      This is why GSMARENA is > all . thank you gsmarena

        • E
        • EskeRahn
        • 0u3
        • 25 Apr 2012

        Nice:)
        Thanks for a great site.
        I'm especially happy on the new display and battery tests *ThumbsUp*
        :)

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