It looks like the iPhone 4 might be [Apple’s] Vista, and I’m okay with that.
A personal website written by Richard Gaywood.
I write about Apple at TUAW, technology and science at Action at a Distance, and about food at Objection: Salad!. I'm on Twitter too: @penllawen. I put pictures on flickr and Instagram.
It looks like the iPhone 4 might be [Apple’s] Vista, and I’m okay with that.
“If you do not use a body-worn accessory supplied or approved by Motorola, keep the mobile device and its antenna at least 2.5 centimeters (1 inch) from your body when transmitting.”
— Droid X User Guide
Oh, no, alert the tech press! This is big news! The gall! The gall!
This text will have come from the “warning, cell phones might cause cancer” bit of the fine print and is a very standard wording. It’s advising you to do that to reduce your absorbed dose, not that Motorola is going to admit that you absorb any radiation from their products. As funny as it is to juxtapose this with the iPhone 4 troubles, it’s irrelevent, because Motorola aren’t saying “keep it away from your body or reception will suffer”.
TUAW has a great post up which shows a video clip of a custom app written by one of their writers, Erica Sadun, that coerces the iPhone 4 into reporting real signal strength values. She shows the now-famous left handed grip dropping the signal from -95dBm (low, but usable) down to -113dBm (nothing). That’s a bigger drop than Anandtech measured, and a much bigger drop than they measured for the iPhone 3GS or the HTC Nexus One.
Meanwhile, wireless technology blog LightReading has another piece which explains on why this issue only effects left handed, and not right handed, grips. As they point out, the small black seam on the right lower side of the iPhone 4 is actually cosmetic — the steel band is split into two parts, not the three it appears to be. You can actually see this in the slide Steve Jobs presented at WWDC but I missed that detail at the time. The piece concludes that “Jeffrey Brown, VP of business intelligence at UBM TechInsights, says the problem is a hardware ‘design issue’ and that the software stuff is, in fact, ‘a smokescreen.’”
As a footnote, Ars Technica notes that the proximity sensor problems I was complaining about may be fixable with a trip to the “reset all settings” feature of Settings.app. I’m going to try that out. (Hat tip to @nickelf.)
Worse for Apple, Antenna expert Richard Gaywood confirmed AnandTech’s study…
This is from Wired.com. Attention Internet: as much as I’m enjoying the attention I’m really not an antenna expert, but that’s the meme propagating around the blogging echo chamber and I need to set the record straight. I’ve even had one of the lawyers for the class action lawsuits contact me to ask if I can be an expert witness for them, and that’s just silly. Let me re-quote what I said in my original piece:
I’m fractionally more than Just Another Internet Dude on this subject. I have a Ph.D in wireless network planning techniques from Cardiff University, and I have worked for Keima, a company writing commercial software that helps cellular operators design their networks for optimum performance. I’m not an antenna engineer by any means, but I do have a modest command of how cellular networks are built.
I am a software guy, and specifically, my thesis (27Mb/361 page PDF) and later commercial work was in the field of cell planning (at Keima, we helped plan the rollout of the Sprint/Clearwire 4G network). I’m not a hardware engineer and I’m not an expert in anything other than the incredibly narrow problem I tackled in my doctoral work. I’m not even employed in wireless technology at the moment, although I do keep current with developments.
Sooner or later some genuine expert with access to proper test equipment is going to get their hands on an iPhone 4 and kick my arse with some real science. Think of me as the paramedic who was first on the scene, not the surgeon who’s going to do the hard work.
A few people and even some significant blogs have asked me what I think of Apple’s open letter to iPhone 4 owners about the reception problems. I guess I’m famous now? Anyway, the important bits of Apple’s press release are:
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.
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.
Having reviewed Anandtech’s excellent research on the issue, I agree with their position:
The drop in signal from holding the phone with your left hand arguably remains a problem. Changing the bars visualization may indeed help mask it, and to be fair the phone works fine all the way down to -113 dBm, but it will persist - software updates can change physics as much as they can change hardware design. At the end of the day, Apple should add an insulative coating to the stainless steel band, or subsidize bumper cases. It’s that simple.
The mapping of signal strength to reported ‘bars’ on the iPhone’s display is oddly out of whack, which causes two problems. For users already in a marginal signal strength area, it makes the drop in reception when they hold the phone look disproportionately — and alarmingly — worse (as the phone can drop from five bars to none). For users in a strong signal area, it masks the issue completely (as the phone’s reception is still inside the five bar range). These are the two positions we’ve seen rage in discussion forums across the Internet over the last eight days (“it sucks!” / “no, it’s fine, you suck!”, etc etc). Basically, it looks like this:
Making the bars more closely represent reality is a step forward, and I believe the perception of the size of the problem has certainly been exaggerated by the miscalibration - with the attendant hysteria from some of the press.
But if there is no design issue at work here, why did Anandtech and my own testing 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?
Apple’s position is that the reception strength is so much better on the iPhone 4 that, even with the attenuation factored in, it’s still better than the 3GS. They, of course, would say that; they’ve just sold a couple of million of the things. Maybe they’re right but I remain unconvinced. The problem isn’t as big as some people are saying — but it’s not the non-problem Apple are trying to paint it as either.
I await my free Bumper with bated breath!
(Edited 2010-07-02 to fix incorrectly labelled graph axis.)
(UPDATE: I have a followup piece about Apple’s new press release here)
This infographic hopefully shows that:
As Anandtech published today, the range of actual signal strengths the iPhone 4 represents as “five bars” is unusually broad. It’s so broad, in fact, that if you are at the top of it, the (quite severe) drop in reception caused by holding the phone with a bare hand isn’t enough to even show up on the display.
Whereas, at the bottom end of the scale, your signal can be quite weak and it will still be shown as five bars on the screen. This is the “worst case” shown above, and taking Anandtech’s figures for attenuation, holding the phone will instantly plunge reception down to a single bar.
I suspect we will be seeing an iOS fix soon that will remap these areas to be more evenly spread out. This will make the problem look rather less alarming to end users, although it won’t change the underlying physics.
I should also note that Anandtech discovered the iPhone 4 to be excellent at hanging on to calls down at low signal levels, so despite the alarming reading where the signal strength meter plunges to zero, the phone itself might keep working perfectly. This is the source for the anecdotal reports of “my phone meter said no signal but my call didn’t drop”. Of course, it’s not magic — reduce the signal much more and it does eventually drop the call, as many other users (myself included) have seen.
As I said before, the bottom line is: signal strength meters are not to be trusted.
(Edited on 2010-07-02 to correct scale on graph, as per the comment below I had mislabelled the axis like some sort of buffoon.)
Previously, I did some simple testing of reception strength on my iPhone 4 and concluded that I couldn’t see any problems. I’ve now done some more thorough testing, however, and have reason to think I was wrong. Warning: this is very long and nerdy.
UPDATE: read Anandtech’s article, they figured out how to make the iPhone 4 display true signal-to-noise ratios and have thus been able to use more rigorous science than I could. They agree with my conclusions though!
UPDATE 2: I have a followup piece discussing the press release from Apple this morning about these problems.
The iPhone 4 is having widely reported issues with signal strength. Users are reporting that when held in the left hand — which bridges two of the externally mounted antennas in a characteristic manner — the signal strength meter drops away.
I have had middling luck reproducing this on my new iPhone. I saw it once, then couldn’t make it happen again no matter how I shifted it around in my hand. Finally, I managed to make it to happen consistently enough for me to do some slightly more scientific tests.
The first test was back-to-back uses of the Speedtest.net client to stress the 3G connection in a manner that is at least vaguely reproducible. The results are above. The differing signal strength readings does not appear to affect network throughout. I re-ran this test a further two times with similar results.
The second test was to place a call with the phone, hand-held, showing 1 bar of network strength. This call lasted several minutes and had no audible artefacts at all.
Conclusion: based on this simple test, I think it is more likely to be some sort of software bug with the signal strength display meter than it is to be an actual radio side interference problem. I accept that there are numerous videos of an iPhone 4 dropping calls as it is handled; however, these all appear to be American phones on AT&T, and AT&T dropping calls is not new news. However, this is a very simple test so it would be wrong to draw broad conclusions from it.