Interference – In So Many Ways

Ever have a problem with a cell phone call and you know what I mean. Your reception fades or you lose the call unexpectedly. There’s so many ways to describe what’s going on and the reasons can vary from excessive cell phone traffic on the cell tower closest to you or inadequate partitioning with your mobile service provider. In the past these were the most common sources of dropped calls and that will continue to happen as our wireless companies upgrade to the new 3G and 4G or LTE standards. Until that day arrives expect lots of the same. Yet an old culprit is here to add to our cell call woes so much so that many of us are thinking back to the days when we had land-lines, which is a good topic to cover in a future post, but that’s not the point here. No, the newest cause du Jour has little to do with the service providers and much more with the interaction of people with their phones, Interference.

So let’s focus on the word for a moment. We all know what it’s like to interfere. If you’re a football fan, you know all about pass interference, that’s when a defender prevents a receiver from catching a fair pass. Well in that way we have a similar problem with our cellular phones. People, us, are getting in the way of our phone calls. Now, in all fairness to us, we’re without fault, mostly. You see, the problem of radio frequency interference is an over simple way of describing what’s really going on because it extends into the aesthetics, economics, and technologies of creating a phone that we love to use and performs to our expectations.

Take aesthetics and Apple’s iPhone 4. You’ve no doubt heard word of mouth reports, maybe read an article like this one, or saw a compelling video that showed what happens when using the phone. If you haven’t then let me describe the problem like this, you take your iPhone 4 and make a call and slowly you lose reception until zip, call dropped. You might initially think like I would that AT&T must be overburdened with lots of calls and from 2000 to 2008 that might have been the case because post 911 the government took up huge amounts of bandwidth in the search for terrorists, but they found none. And at any moment, the government make snatch the airwaves again, but I’m neither anti-government nor a conspiracy hack, it’s just a plain fact that what the man needs, the man takes!

So wait let me get back on topic of looks. You see Apple is famous for eye pleasing designs, owners of any of their PCs will know what I mean. Apple makes products look good with great performance too, right? Well, their driving motivation is to let their industrial (style) designers have a final say in product development. It’s worked so well with their latest iPod, the iPad, and of course the iPhone.

So what do looks have to do with dropped calls?

It’s not an easy answer, but let me try to explain. Embedded inside your cell phone is a snug little circuit board, full of microchips, electronic parts, and antennas for sending and receiving wireless signals. When connected together these little devices allow you and me to make our phone calls. In order to make that happen we need a cell phone circuit designer. That cool designer dude or hip dudette will line up the chips and parts, making them work at their best and if left alone they’ll give you a circuit board that works, but it may be ugly. The problem at Apple is likely that their industrial designers didn’t like the first iPhone 4 circuit. In that first design, the antennas may have been on the back of the phone or on the top or well wherever the circuit designers knew would be out of the way of our hands whenever we made a phone call. But that’s not how design works at Apple. Their industrial designers are about making products that are beautiful inside and out. In the case of the iPhone 4 they symmetrically integrated the antennas into the outer case where we normally put our hands to make a call. We get in the way. The interference – our hands and bodies – block the iPhone 4′s reception. So who’s fault is that? Easy to figure right? Right.

Now take economics. In Apple’s case there a solution. Put the antennas out of the way of us. Problem solved. But that’s not the case with every cell phone maker. Often because of the design, there’s no getting around putting the antennas where we get in the way. What then? Let’s use the football analogy from above again. Most football teams are smart to have more than one receiver out on the football field in the case where a defender is blocking one of the receivers then the quarterback can choose another receiver. Or if they’ve got just one receiver then why not get the tallest and biggest one possible? That way the defenders (blockers) can’t affect him. Well in cellphones it’s possible to use more than one antenna or to make the antenna larger! The concept like in football is called redundancy. Redundancy helps create back up solutions. Here’s where we get into economics. In order to provide a phone that’s got more than one antenna or even a big antenna, the cell phone maker has to spend more on the technologies (antenna, microchips, and electronics). In the end we end up paying more $$$ for that phone. Who wouldn’t mind paying more for better reception? More than 50% of America, that’s who. We like getting our phones for free with a two year contract and if they charge us $100 who cares as long as we get a good phone. Our “who cares” reply changes when we’re told that we have to pay $30o and still have a two year commitment. In Apple’s case, their iPhone 4 might cost as much as $500 with more antennas. Aha, you’re getting it now.

Well, there’s one last issue at play. We touched on it with antennas. Extra antennas cost $$$ and we the buying public end up paying for the enhancements. But there’s another way that’s still a bit costly, but not so much. Like in football, if a team has just one receiver and he’s not a 7 foot tall phenomenon then what? You get a receiver that’s got talent and most important agility. A great receiver can escape a good defender and still make the catch. Great receivers, you know their names, also play quarterback from time to time. What about blocking. If one receiver can make a catch, what’s to stop his teammate from blocking the safety (defender) from getting in the way. Well in cell electronics it turns out that there are technologies such as filters that act to block out unwanted interference, but they’re costly and take up space. Better still are technologies that let the cellphone tune its antennas in much the same way that a great receiver knows to get around a defender. These tuning circuits, called tunable matching networks, make the antennas compensate when we hold the phone or when there’s something else interfering with a call. The tunable technology is still kind of new, but when it hits volume production, it’ll allow Apple and others to put their antennas wherever they want, even for looks.

Interference, like I described it here, is a far too simple of a description of the problem. There are other issues like inter-modulation and close proximity cross coupling and so on. The bottom line is that as cell phones become more and more like pieces of art, which we expect to work like our personal computers, we will see more problems with dropped calls OR we’ll have to get used to the idea of paying more money for technologies that work every time. I predict that Apple’s iPhone 4 will be the one of the last phones where this is a problem. Why? Well, most cell phone makers are smart, they understand the problem of interference and they don’t care if a phone isn’t pretty on the inside (if the outside looks nice) as long as it works. Even then, as we get access to 4G and LTE we’re going to see the problem more and more. Apple’s mistake is a free lesson for Motorola, HTC, Samsung, RIM, and LG. If they’re smart, they won’t do as Apple did. They’ll let the circuit designers do their job and if there’s no getting around the problem of interference then they’ll have to use the new technologies I mentioned in order to make their phones work and that means we pay more. I guarantee it.