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Apple: Our Formula to Calculate Bars of Signal Strength on the iPhone 4 Is “Totally Wrong”

In an unusual display of corporate transparency, Apple has just released a statement detailing the signal problems many iPhone 4 users have been complaining about since Day One. According to Apple, the four- and five-bar drops in signal often experienced when one holds the lower left corner of the iPhone are not the result of faulty antenna engineering, as has been widely speculated.

But there’s still a real problem: Apple says that an inaccurate signal strength formula has caused many iPhone 4s to greatly overreport the number of bars worth of signal they’re currently receiving.


Upon investigation, we were stunned to find that the formula we use to calculate how many bars of signal strength to display is totally wrong. Our formula, in many instances, mistakenly displays 2 more bars than it should for a given signal strength. For example, we sometimes display 4 bars when we should be displaying as few as 2 bars. Users observing a drop of several bars when they grip their iPhone in a certain way are most likely in an area with very weak signal strength, but they don’t know it because we are erroneously displaying 4 or 5 bars. Their big drop in bars is because their high bars were never real in the first place. [emphasis added]

To fix this, we are adopting AT&T’s recently recommended formula for calculating how many bars to display for a given signal strength. The real signal strength remains the same, but the iPhone’s bars will report it far more accurately, providing users a much better indication of the reception they will get in a given area. We are also making bars 1, 2 and 3 a bit taller so they will be easier to see.

We will issue a free software update within a few weeks that incorporates the corrected formula. Since this mistake has been present since the original iPhone, this software update will also be available for the iPhone 3GS and iPhone 3G.

Apple still claims that “the iPhone 4’s wireless performance is the best we have ever shipped,” but their “fix” merely displays a weaker signal rather than directly confronting the antenna blockage problem. Once again, it appears that Apple’s mobile platform is taking the fall for the real culprit — AT&T’s subpar wireless network. But from the sounds of this release, Apple probably will not be giving free bumpers to the victims of performance problems anytime soon.

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