JeffKirvin.net

There has been, well, some vig­or­ous dis­cus­sion this past week about the iPhone 4 and what those bas­tards at Apple have foisted upon us. Peo­ple are los­ing their freak­ing minds. Law­suits have been filed. Peo­ple are threat­en­ing to take their phones back. And, of course, peo­ple have emailed Steve Jobs directly, with results of vary­ing veracity.

Only, the thing is, it’s really not such a big deal. I know peo­ple are angry, and they have every right in the world to feel that way. And I know Apple has been unusu­ally tone-​deaf in how they’ve han­dled this sit­u­a­tion, but I also think they’re doing the right thing. So let’s take a step back, look at the sit­u­a­tion for what it really is and see how this all sorts out. (This would be a good place to take your happy pills if you need them.)

Design

The sin­gle most strik­ing fea­ture of the iPhone design, which you notice even before you see the ZOMG drool­wor­thy screen, is the stain­less steel band sand­wiched between the two plates of glass. This is not only the struc­tural sup­port for the phone, but also the antenna. The left side, from the head­phone jack around past the vol­ume but­tons, is the WiFi/​Bluetooth antenna, and the rest is the cel­lu­lar antenna. While this design choice sim­pli­fies and min­i­mizes the lay­out of the phone, it also means that you will, in the act of hold­ing the phone, alter the the recep­tion of the phone as you, who are essen­tially a bag of salt water as far as RF sig­nals are con­cerned, change the con­duc­tiv­ity of the antenna.

The result is what has become known as the “iPhone Death Grip.” If you hold the phone so that your skin bridges the tiny gap between the WiFi and cel­lu­lar anten­nas, you can watch in awe and/​or hor­ror as your sig­nal bars drop from five to one. This “design flaw” is what all this fuss is about.

Sig­nal atten­u­a­tion, by the numbers

Sure seems like a design flaw, right? To go from full sig­nal down to noth­ing just by touch­ing the phone? Touch­ing the phone in the exact same way you see Steve Jobs hold­ing it in just about every pic­ture of him and the iPhone 4 on the web?

Well, maybe, maybe not.

See, the truth is that five bars can be well removed from “full sig­nal,” and even that’s kind of a mis­nomer left over from ana­log phones that doesn’t mean much in a dig­i­tal world. Let’s look at the actual math for a minute. This won’t hurt a bit.

RF sig­nals are mea­sured in neg­a­tive deci­bels. The best sig­nal you can get, stand­ing right next to the tower, is –51 dBm. The worst is –113, the point at which AT&T’s tow­ers just stop try­ing to talk to you. Now, you would think that the bars would be evenly dis­trib­uted over that 65 dBm range. But the prob­lem is that it’s a log­a­rith­mic scale. –100 dBm is ten times weaker than –90 dBm.

As a result, you see a “full” five bars all the way down to –90 dBM. Mean­ing as soon as you start los­ing bars at all, you’re not approach­ing the cliff, you’re already falling off.

This is already con­fus­ing, but it gets worse. When you touch the antenna, depend­ing on con­di­tions (mois­ture, etc.) you will cause the sig­nal to drop by 20 – 24 dB. If you’re in a strong “five bars” area, this will still leave you with more than 90, and thus still have “five” bars. If you’re sit­ting right around 90, drop­ping 24 dB can drop you all the way down to the cut off point, even though you started with “five” bars.

Pass­ing the bar

Only, even that isn’t really the case. Because as I men­tioned before, the whole con­cept of bars is a hold-​over from ana­log cell phones and doesn’t really make sense in a dig­i­tal world. With dig­i­tal cell phones, sig­nal is a binary con­di­tion. Either you have enough sig­nal to make the call, or you don’t. (It’s the same way with dig­i­tal TV over the air now. You either get a per­fect pic­ture or you get noth­ing, no more snow that kinda resem­bles your favorite show.) Numer­ous reports have shown that the iPhone 4 holds on to a call just fine all the way down to –111 dBm, and holds calls in places the iPhone 3GS would have dropped or not shown ser­vice at all.

Apple con­tends that the iPhone 4 has the best recep­tion yet of any iPhone, and even with the atten­u­a­tion prob­lem fac­tored in, this does in fact seem to be the case. Per­son­ally, I’ve lost a grand total of one call that I can blame defin­i­tively on the Death Grip. Granted, when I touched the antenna and dropped the sig­nal enough to drop the call, I was already in an under­ground park­ing garage. o_​O

Bump the Bumper

Apple raised eye­brows at WWDC when they announced the iPhone 4 by also announc­ing their first ever case for the iPhone, some­thing they’d pre­vi­ously left to third party com­pa­nies. The Bumper is a min­i­mal­ist case that only cov­ers the steel band around the iPhone, leav­ing the glass front and back mostly uncov­ered. Once reports of prob­lems with the antenna sur­faced, it didn’t take long for peo­ple to fig­ure out that 2 + 2 = Con­spir­acy Theory!

Obvi­ously, they say, Apple knew about this prob­lem, and that’s why they’re rip­ping us off to the tune of $30 for a band of rub­ber and plas­tic to cover up the prob­lem they knew they had! Those bastards!

Maybe, maybe not.

I’ll admit the Bumper is sus­pi­cious. And yes, it does seem to reduce, but not com­pletely elim­i­nate, the atten­u­a­tion. But a wise man once advised to never attribute to mal­ice what could be explained by sim­ple incom­pe­tence. And I can also see not only why Apple would have offered the Bumper with­out know­ing any­thing about the sig­nal issue, but how they never would have seen the sig­nal issue.

The Bumper is good for more than just antenna insu­la­tion. It also pro­vides a good deal of shock absorp­tion, some­thing at which steel and glass are noto­ri­ously bad. An iPhone 4 wear­ing a Bumper is much less likely to crack or shat­ter when dropped to a hard sur­face on the cor­ner than a naked iPhone. So Apple could have pro­vided it sim­ply because they knew the iPhone 4 might ben­e­fit from the extra protection.

As for them know­ing about the sig­nal issue, think about how this prob­lem man­i­fests and how Apple tested the phone. You don’t see it at all in strong sig­nal areas where even drop­ping the full 24 dB still leaves you with five bars. And within the Apple cam­pus at Cuper­tino, you can bet they have impec­ca­ble AT&T sig­nal. So on cam­pus, they’d never notice it.

Of course, they don’t just test it on cam­pus. In fact, we know at least one radio base­band engi­neer who, while test­ing the phone in a bar, had a lit­tle too much Ger­man beer and wound up with­out his pro­to­type iPhone 4. But we also know from that lit­tle escapade that when off of Apple’s cam­pus, the iPhone 4 was hid­den inside a spe­cially built case that made it look like a 3GS. And hold­ing it inside that case would have insu­lated the antenna, sim­i­lar to how the Bumper works, which means they wouldn’t have seen it there either.

In short, Apple’s test­ing method­ol­ogy seemed to guar­an­tee that they’d never the test the iPhone naked and in poor sig­nal at the same time. When they say they were “shocked” to dis­cover this prob­lem, I believe them. I really don’t think they tested it in all pos­si­ble conditions.

Don’t hold it that way

Appar­ently, Apple was caught so off guard by this con­tro­versy that they they stum­bled repeat­edly in deal­ing with it in pub­lic. The first time a user emailed Steve Jobs him­self about it, or at least the first (only?) one Jobs replied to, Jobs actu­ally told the guy not to hold it that way. This struck most peo­ple as flip­pant and dis­mis­sive, which is prob­a­bly why Apple quickly fol­lowed up with an offi­cial state­ment with more care­ful word­ing. BGR reported that Jobs also had a longer exchange with some­one else where he ended up telling the user to get over it, it’s just a phone. Apple claims this con­ver­sa­tion is a hoax, though BGR stands by their report­ing.

What we do know is that Apple’s offi­cial stance at the time of this writ­ing is that all phones have this issue to one degree or another, but that iOS4 has badly cal­i­brated sig­nal bars that don’t give peo­ple a real­is­tic idea of how likely they are to drop a call. This seems to be true, as peo­ple have been able to grip other phones from the Moto RAZR to the Google’s Nexus One in ways that cause sim­i­lar sig­nal drops, and the “hey, my bars are drop­ping like flies” effect is show­ing up on older iPhones that have been upgraded to iOS4. Apple is not recall­ing the phone or even offer­ing free Bumpers as a mat­ter of pol­icy. Instead, they’re going to address this with a soft­ware fix.

Can’t fix the sig­nal, so fix the bars

Wait a sec­ond. How can a soft­ware fix resolve a phys­i­cal design issue? Because, as with every­thing in this story, things are more com­plex than they seem.

The iPhone 4 han­dles sig­nal dif­fer­ently than other iPhones. Dif­fer­ently than other phones, as near as I can tell. Pre­vi­ously, iPhones tried to home in on the strongest sig­nal from a tower they could find. The prob­lem is that the tower they’re clos­est to – thereby pro­vid­ing the strongest sig­nal – might also be the most crowded. Or there might be more elec­tro­mag­netic inter­fer­ence in that area. So even though the sig­nal is stronger, your call qual­ity might actu­ally be worse.

The iPhone 4 seeks out the “best” sig­nal, not nec­es­sar­ily the strongest. It looks for clar­ity, lack of inter­fer­ence, low traf­fic on the tower. As a result, and keep­ing with dig­i­tal calling’s binary nature, you “do” have a sig­nal with the iPhone 4 more often than you “don’t” com­pared to older iPhones, even if the reported sig­nal strength is a lower number.

Apple is going to change the way the bars are dis­played so they fol­low AT&T’s guide­lines on how many bars to report for a given sig­nal strength. This seems to be another source for angry mis­un­der­stand­ing among the digerati, so pay attention.

Coun­ter­in­tu­itively, this change is going to show fewer bars than you had before for any but really strong sig­nals. Where you used to have four or five bars, you might now only see two. But, and this is impor­tant, those two bars are more “durable” and a more accu­rate indi­ca­tor of what kind of sig­nal you’ve actu­ally had all along. You never really had the kind of sig­nal strength you thought you did if you used to see five bars and now you see two after installing the patch. You always had “two bar” strength, you just didn’t know it. Every­one clear on that?

Let me sum up

So. Should you hold off on buy­ing an iPhone 4 because of this issue? If you already have one, should you take it back? That depends. Are you drop­ping calls? Are you drop­ping more calls than you did with your pre­vi­ous phone, iPhone or not? If not, then I wouldn’t worry about it. As men­tioned above, the iPhone 4’s antenna is actu­ally bet­ter than the 3GS at hold­ing on to a call at low sig­nal strength, so for all prac­ti­cal pur­poses the num­bers don’t matter.

Per­son­ally, my iPhone 4 per­forms at least as well as my iPhone 3G, and offers so many advan­tages besides, so I’d be a fool to take it back. Do I use a case? Some­times. Some­times not. I keep mine in a Grif­fin Élan Pass­port Wal­let when I’m on the go along with my driver’s license and debit card. But I take it out fre­quently to sync, use around the house, for use as a GPS and when typ­ing or watch­ing video in the Grif­fin Travel Stand (no, I’m not spon­sored by Grif­fin, but I wouldn’t turn them down; I like their prod­ucts). In or out of a case, I don’t notice the “prob­lem” much. It’s just not an issue. Put aside the hype and noise, and you might see the same.