Apple: iPhone signal bars are bullshit

Those little bars on your cell phone are bullshit, as Apple acknowledged in an email today.

“Our formula, in many instances, mistakenly displays 2 more bars than it should for a given signal strength,” Apple’s letter reads. “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.”

So they cheated on the bars to make the signal strength appear better than it was.

A software fix due to be released in the coming weeks will adopt AT&T’s guidelines for signal strength reporting, which will result in a more accurate portrayal of reception on the iPhone 4.

And got caught.

Testing of the iPhone 4 found that holding it in the left hand and covering the left side of the device can reduce reception by 24 dB. For a user with a “weak,” incorrectly reported five bars, this can result in a dramatic reduction of bars on the iPhone 4.

Because the new iPhone design has a little problem with the antenna.

24 Db is a huge signal loss. A 3 Db loss is half the signal strength. 24 db is just 1/16th of the original signal strength. Just from holding it in your hand.

Gee, who would have thought that people might hold a cell phone in their hand?

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12 Responses to Apple: iPhone signal bars are bullshit

  1. mike w. says:

    I’m a lefty, so that would really suck.

    No Iphone 4 for me.

  2. Joe Huffman says:

    Sorry. I’m a nit-picky (ex) electrical engineer.

    It is a signal loss of more than 250 times.

    dB = 10 log(PowerRatio)
    dB/10 = log(PowerRatio)
    PowerRatio = 10^(dB/10)

    PowerRatio = 10^(-24/10)
    PowerRatio = 1/251.15

    You conclusions are valid but you understated your case.

  3. Joe Huffman says:


    You were expressing it in terms of voltage. Not power.


  4. LibertyNews says:

    Not a surprise to me. When I see full bars and 3g while sitting in my basement I know something’s up. I reboot the phone and have 2 bars and no 3G which is more accurate. This is on a 3G so they’ve been fudging the bars since the beginning.

  5. alan says:


    Honestly I’m not sure what terms I was expressing it in. Not being an EE. 🙂

    My radio knowledge is from being a ham and running terrestrial microwave towers, not in design.

    I just know that a change of 3Db is a doubling or halving of signal strength and went from there.

    I’m still baffled that someone thought that holding a radio by it’s antenna was a good idea.

  6. Joe Huffman says:

    dBv = 20 log(VoltageRatio)
    dBv/20 = log(VoltageRatio)
    VoltageRatio = 10^(dBv/20)

    In most communication applications its the voltage change that is important rather than the power. It’s a lot easier to accurately detect and measure voltage than it is power.

    So saying 1/16th (actually 1/15.85) the signal strength is a more accurate way to express the problem from the electronics viewpoint. This is because internally they detect the signal via voltage fluctuations rather than concern themselves with the actual power of the signal.

    A change of -3dB is 1/2 the power or 1/SQRT(2) of the voltage. You were mixing voltage and power measurement which got me off on the wrong foot.

    Typical nit-picky geek. Derailing the conversation with irrelevant, in the present context, details. Sorry about that.

  7. alan says:

    LOL Joe. “Derailing the conversation”

    You HAVE listened to Vicious Circle, right?

    Derailing the conversation with geeky details is what we do.


  8. Someone needs to hire better programmers…

  9. maddmedic says:

    Whats an iPhone4?
    What happened to the first 3?
    Are the people that designed the iPhone the same ones that decided to put the oil filter in my wife’s car in a spot I need to break my arm in two additional places to reach?

  10. Joe Huffman says:

    I’m proud to say I’m on the team working on the next iPhone.

    We call it Windows Phone 7–from Microsoft.

    (Side note: My tester and I left the building at 1:30 AM this morning. We got the bugs fixed and the tests updated. There was much rejoicing by the Program and Dev Managers this morning.)

  11. DirtCrashr says:

    Steve Jobs doesn’t have to hold onto it, it levitates on a beam of self adoration inside the reality displacement field.

  12. Brigid says:

    I’d comment but I have a cell phone that’s a bit outdated. People look at it (it’s about the size of a Humvee) and ask “well, that’s interesting, what does it do”. To which I reply. “It rings”.

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