Apple's iPhone 4 "fix" fails to make sense

Apple has responded to the iPhone 4 antenna problems, as reported by many users. This response is being widely seen as a promise of a fix - indeed, Apple claims to fix something in the statement - but it's not as simple as that.
Written by Rupert Goodwins, Contributor

Apple has responded to the iPhone 4 antenna problems, as reported by many users. This response is being widely seen as a promise of a fix - indeed, Apple claims to fix something in the statement - but it's not as simple as that. Let's take a look at exactly what Apple says, and try to tie it to what we know about radio in general and the iPhone 4 in particular.

July 2, 2010

Letter from Apple Regarding iPhone 4

Dear iPhone 4 Users,

The iPhone 4 has been the most successful product launch in Apple’s history. It has been judged by reviewers around the world to be the best smartphone ever, and users have told us that they love it. So we were surprised when we read reports of reception problems, and we immediately began investigating them. Here is what we have learned.

"We were surprised..." means that whatever testing Apple had done with the iPhone 4 never revealed the problem being reported. Surprising indeed: testing a phone's reception is an extraordinarily important part of the development process. Your relationship with your carriers, your legal responsibilities of compliance with radiation standards, and your subsequent support costs are all determined by knowing this information.

To start with, gripping almost any mobile phone in certain ways will reduce its reception by 1 or more bars. This is true of iPhone 4, iPhone 3GS, as well as many Droid, Nokia and RIM phones. But some users have reported that iPhone 4 can drop 4 or 5 bars when tightly held in a way which covers the black strip in the lower left corner of the metal band. This is a far bigger drop than normal, and as a result some have accused the iPhone 4 of having a faulty antenna design.

Apple seems to be unable to say the word 'Android'. It's also not admitting there's a problem - although it does claim that everyone has it - but it's not saying it doesn't have the problem. Apple merely says that users report and users accuse. Did Apple reproduce the problem in the labs? It's not saying - which probably means, yes it did.

At the same time, we continue to read articles and receive hundreds of emails from users saying that iPhone 4 reception is better than the iPhone 3GS. They are delighted. This matches our own experience and testing. What can explain all of this?

We have discovered the cause of this dramatic drop in bars, and it is both simple and surprising.

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.

This paragraph is, on the face of it, difficult to believe. Signal strength - and signal strength reporting - is so fundamental to the development process of mobile phone hardware. and so much attention is paid to it in design and testing, that it is almost inconceivable that this sort of problem would get through. The algorithm that takes the signal reported by the radio hardware - which will be an absolute figure in decibels - and converts it to the on-screen display will be based on standard maths. During software and hardware development there will be a huge number of occasions when radio engineers look at both the absolute signal level and the on-screen indication.

And then 'the high bars were never real'. Miscalibrated, perhaps, but hardly unreal. Something is dropping: a fact that Apple does not deny or address. It is impossible to say what the scale of the initial problem was, nor what the new software will do. Apple could be more precise here: it chooses not to. But this is clear: Apple is saying that there is a drop-off in signal strength, and that all it can do is change the way it is reported. The company clearly hopes that we'll infer the problem is just the same on other phones - but it never says that.

It's like a car maker responding to complaints that one of its models becomes difficult to steer at certain speeds, by saying that the problem lies with the speedo being miscalibrated.

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.

"To fix this" - to fix what? Without more information - technically, the transfer function that converts the signal strength in dBm to the discrete steps in the signal meter - this statement is meaningless.

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.

If 'this mistake' has been present since then, and it merely reflects an issue that's also commonly found, how come it hasn't been reported by anyone until the iPhone 4? What makes the iPhone 4 uniquely sensitive to the problem? It can't be the algorithm.

We have gone back to our labs and retested everything, and the results are the same— the iPhone 4’s wireless performance is the best we have ever shipped. For the vast majority of users who have not been troubled by this issue, this software update will only make your bars more accurate. For those who have had concerns, we apologise for any anxiety we may have caused.

And those who say that they have actual problems making calls and connections? You were wrong, apparently. Perhaps Apple would like to share those test results, too: they won't be commercially sensitive, because they can be trivially reproduced by competitors, unless they reveal something Apple would rather we didn't know

As a reminder, if you are not fully satisfied, you can return your undamaged iPhone to any Apple Retail Store or the online Apple Store within 30 days of purchase for a full refund.

We hope you love the iPhone 4 as much as we do.

Thank you for your patience and support.


There we have it. A problem that is never properly described receives a 'fix' that cannot change whatever it is that really happens.

To be at all convincing, Apple should publish actual figures from testing, including when the problem is triggered. The press release as it stands is at best misleading: it's certainly confusing, ambiguous and illogical.

[Update - Anandtech has a stonking practical examination of the problem, which is as convincing as anything in this saga (hat-tip to @tug for pointing that out). I didn't know that Apple had actualy removed the standard field test function from the iPhone 4 - which in previous models produced a calibrated dBm signal reading, allowing investigation of the issue.

Anandtech's conclusions, which I think are spot on, are that the iPhone 4 has superior radio reception except for the antenna issue, which can cripple it. I can't see how this wouldn't have come to light the very first time Apple had working case prototypes: my guess is that a redesign to fix the problem would have been such a massive reworking, the company chose to ride out the problem. Nothing Apple has done or said goes against this analysis, in my opinion.]

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