Four Bars, Three Bars, Two Bars, One Bar

Apple:

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.

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.

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.

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.

Clive Crook:

Don’t say I didn’t warn you about the new iPhone. (I just had a hunch.) Interesting to see how Apple switched today from, “it’s not an issue, you’re just holding it wrong,” to, “it’s not a reception issue, it’s just that the signal strength indicator tells you you’ve much better reception than you have–and by the way previous iPhones have the same defect.” So after all that fuss, the answer is really very simple. And you all thought there was a problem!

Richi Jennings at Computerworld:

The upcoming firmware patch will make the bars display differently. Perhaps in a way more consistent with the way other phones do it.

The patch will not fix the actual problem. It should be clear to anyone who has a little understanding of RF, that allowing users to touch an antenna in such a way as to change its impedance will have a significant effect on signal strength and quality — possibly improving it, but usually making it worse.

Yes, holding older iPhones also caused reduced signal, but to nowhere near this extent. The more scientific tests — such as those performed by Brian Klug and Anand Lal Shimpi — show that actual signal strength as measured by the UMTS hardware is reduced by 10 or 20 dB more on an iPhone 4 than on an iPhone 3G.

Don’t forget, this is a logarithmic scale: a 10 dB reduction is a 90% loss of signal. 20 dB is a 99% loss: basically catastrophic, unless you’re really close to the cell tower and not in an environment with too much RF noise.

The iPhone 4 antenna design is certainly innovative, but as I said last week, those of us with a little understanding of RF knew that a bare metal antenna was going to be trouble, as soon as we saw the pre-production unit lost in a bar. The natural assumption was that Apple would cover it with a transparent film; I can only speculate as to why they didn’t.

Still, from early indications, it looks like the Apple fanbois are lapping up the explanation. The famous reality distortion field strikes again: it’s not a design flaw, just a firmware bug.

Jesus Diaz at Gizmodo:

Michael Anderson, who used to work at Motorola’s FCC testing lab, points out that “it’s a fundamental flaw that can only be fixed through a redesign. If that is redone, all the FCC will have to be completed again. This may be a long slow process to fix.”

In his reply to Apple’s letter, Richard Gaywood—PhD on wireless network design from Cardiff University—thinks the signal display fix is a good step to fix user perception, but it won’t fix the antenna interference problem that exists in the iPhone 4:

But if there is no design issue at work here, why did Anandtech and I both show significantly different attenuation when holding an iPhone 4 in a bare hand compared to holding it in a case? And why did Apple themselves recommend “using a case” as a possible solution to the problem?

The antenna interference problem

According to wireless experts consulted by Gizmodo, the iPhone 4 antenna interference problem happens to everyone, and it’s not a matter of signal bars displayed in the phone. However, some people are not noticing it. Why?

Scientific tests conducted by Anandtech, there’s always up to a 19.8dB signal loss when you grab the iPhone naturally with your hand, with your skin touching the deadly spot. That’s losing signal by a factor of almost 100.

This technical measuring has been demonstrated empirically in both voice calls and internet access by thousands of users around the world, independently of their network.

Robin Wauters at TechCrunch:

I trust by now you’ve read Apple’s letter claiming that there’s absolutely nothing wrong with the antennae on the iPhone 4, and that any real reception issues are inexistent and merely a result of faulty displaying on Apple’s part, which it intends to fix in the coming weeks.

Unimpressed by that statement? You’re not alone.

Mason LLP, one of the multiple firms that have filed a class action lawsuit on behalf of customers who recently purchased the iPhone 4 alleging that the antenna on the phone is in fact defective by design, isn’t terribly impressed either.

The firm, which filed the lawsuit seeking an order requiring Apple to ship a protective case for the iPhone 4 to all consumers who purchased one as well as monetary damages, provides us with the following statement after reading and analyzing Apple’s letter:

Our investigation revealed that users lost reception when gripping the phone in a conventional manner. We believe that the problem is not merely how the signal strength is displayed but involves a physical blocking of the antennae which cuts off calls.

In other words, don’t expect those lawsuits to go away now that you’ve written up your version of the truth, Apple.

UPDATE: Farhad Manjoo in Slate

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One response to “Four Bars, Three Bars, Two Bars, One Bar

  1. Pingback: What We’ve Built This Weekend « Around The Sphere

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