July 2015

Mobile data at US airports and on major US airlines

by Joey deVilla on July 7, 2015

airplane takeoff

If you’re a reader of this blog, it’s quite likely that when you go to the airport, as soon as you’ve cleared security and found a perch at your departure gate or on your flight, you typically take out a mobile device and go online. You’re not the only one: look around on any plane or any airport lounge, and you’ll easily see dozens of people staring at glowing rectangles in their hands. Air travel consists largely of sitting and waiting, whether on the ground and in the air, and these days, much of that sitting and waiting is made a little less tedious by going online.

Mobile data performance in America’s busiest airports

departure lounge

Creative Commons photo by Phillip Capper. Click the photo to see the source.

The mobile networks performance research firm RootMetrics regularly posts their “RootScore” reports of mobile data performance by the major US carriers in various locations across the country, including airports. Their latest report on mobile data performance at the 50 busiest airports in the nation appears in their 2nd Half 2014 US Airport Mobile Network Performance Review, published in March. It shows how individual carriers’ networks perform at airports, in terms of online access for web sites and apps (which is one matter) and the completion of tasks (a completely different matter).

Yes, many airports do offer free or paid wifi service, but it’s often spotty, overloaded, and slow. There are many times when it’s better to go online using your own mobile data — especially if you have an all-you-can-eat plan — and that’s why this information is so useful.

The infographic below shows a quick summary of the RootMetrics report on airports, but we recommend that you read their writeup for the full story:

mobile data at us airports

Click the infographic to see it at full size.

Wifi offerings on US airlines

in-flight wifi light

While on the ground, you have the option of using your own mobile data plan or going with airport wifi. In the air, where you can’t use your cellular connection but are now allowed to use wifi (which will eventually change the meaning of “airplane mode”), you have to go with whatever wifi service the airline offers.

More recently, Fortune published the article The crazy economics of inflight wi-fi, where they astutely observe that many of the normal rules don’t apply. Paying more doesn’t necessarily get you better bandwidth, and that’s because the various airlines’ wifi services have different business models (most are treating it as a profit center, a handful as a differentiator) and technology (varying satellite technologies, as well as ground-based cellular services specifically set up for air travel). Another factor is that you’re sharing bandwidth with anyone else on the plane who’s using it. If you’re on a flight full of Poindexters doing business while en route, prepare for sluggish connectivity; if you’re on a red eye where everyone’s asleep and you’re on a deadline and pumped full of espresso or Red Bull, that bandwidth might be all yours.

As with the previous story, we’ve made a nice summary infographic for you, but it’s worth it to read the full article:

in-flight wifi on us airlines

Click the infographic to see it at full size.

What do all these bandwidth numbers mean, anyway?

speedometer

Simply put, “bandwidth” refers to the speed at which data is transmitted in a network, and these days it’s typically measured in Mbps, short for megabits per second. If you recall, all computer information boils to down to ones and zeroes — binary digits, or bits for short — and a megabit is about one million of those bits. The chart below should make numbers and rates of bits more meaningful:

Speed
(in Mbps)
Email a picture
(1.5 MB, or 12 million megabits)
Download a song or long PowerPoint presentation
(8 MB, or 64 million megabits)
Download an ebook or short video
(20 MB, or 160 million megabits)
20+ less than 1 second <4 seconds 8 seconds
10 2 seconds 7 seconds 16 seconds
5 3 seconds 14 seconds 32 seconds
1 12 seconds 64 seconds 160 seconds

this article also appears in the GSG blog

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maxwell sound and his shoe phone

Maxwell Smart, the protagonist of the 1960s spy comedy Get Smart, and his shoe phone,
quite possibly the first mobile phone to make regular appearances on a TV show.

swift kickWhile answering this question on Stack Overflow, I noticed that in the “Related” list running down the right-hand side of the page that there were several similar questions. They essentially asked the same question:

I’m not getting any errors, so why isn’t the AVPlayer or AVAudioPlayer in my iOS app playing anything?

I’ve seen this question asked often enough that I’ve decided to post this article as an answer that I can point to from now on.

Here’s the short answer:

Because your AVPlayer or AVAudioPlayer went out of scope just as the sound started playing.

The long answer, complete with code examples, appears below.

To make my point as clear as possible, the examples will be simple: they’ll be attempts at creating an app that plays an MP3 located at a given URL. That way, all you have to follow along is either type in or copy-and-paste code without having to bring a sound file into your project. While these examples use an AVPlayer object to play an online MP3, what I’m demonstrating is equally valid for apps that use an AVAudioPlayer object to play an MP3 stored as a local file or in memory.

First, let’s do it the wrong way

Many “why isn’t my app playing any sounds?” questions on Stack Overflow include code snippets that make the same mistake that I’m about to demonstrate. Fire up Xcode and follow along…

xcode new single view application

Create a new single view Swift application in Xcode, then replace the contents of ViewController.swift with the following code:

Feel free to run it in either the simulator or on a device. You’ll see a blank screen and hear…nothing. The only feedback you’ll see in the app is in Xcode’s output pane, where you’ll see the messages from the println functions:

output

If you look at the code, you’ll see that everything happens in the viewDidLoad method. The output from the println functions — combined with the lack of error messages and the fact that the code compiled — suggests that code in viewDidLoad is being executed, even though you’re not hearing anything.

Take a look at where the AVPlayer instance is created. It’s inside the viewDidLoad method, which means that its scope is limited to viewDidLoad. Once viewDidLoad has executed its final line, the println function that outputs “…and we’re playing!”, all its local variables go out of scope, including avPlayer, which contains the reference to the AVPlayer object that’s supposed to be playing the MP3. Without that reference, that AVPlayer object gets cleaned up by the system and gets zapped out of existence. Simply put, the app did start playing the MP3, but stopped very, very shortly afterwards; probably on the order of milliseconds.

viewdidload 1

Hopefully, what I just told you gave you the hint for making the app work properly. Let’s try doing it the right way…

The right way

Replace the contents of ViewController.swift with the following code:

Note the difference: this time, we’re creating avPlayer as an instance variable. That means that its scope is the viewController instance. As long as the viewController exists, so will avPlayer. And since this app has only one view controller, it means that avPlayer — and the AVPlayer object it references — will exist as long as the app is running.

Try running the app again. As long as the simulator or device can access the ‘net and there’s actually an MP3 at the URL specified in urlString, you’ll hear that MP3 playing.

viewdidload 2

Once again: the answer to the problem is that your AVPlayer or AVAudioPlayer instance needs to be scoped at the view controller level, and not at the level of a method. That way, the player exists as long as the view controller instance does.

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Organizational structures: a survival guide

by Joey deVilla on July 1, 2015

Doghouse Diaries has a great infographic that explains how to survive within the major organization types:

org structures

Infographic created by Doghouse Diaries. Click to see the source.

Related reading: Org charts of the big tech companies.

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