Working of iPod Touch

How the iPod Touch Works

When Apple released the iPod video in 2005, people started wondering what the next version of the iPod would look like. It seemed obvious that the media player needed a bigger screen. While a 2.5-inch LCD was fine for browsing through lists of artists and songs, it was far too small for watching videos, especially in a widescreen format.

The iPod touch.

The basic iPod design is pretty sleek, and making it bigger to accommodate a larger screen would take away a lot of its charm. So many Apple aficionados speculated that the next iPod would be all screen. It would have a virtual Click Wheel, and it would play widescreen videos on a horizontal display.

The theorists got it partly right. The newest iPod design is the iPod touch. A display screen covers most of the front surface of the iPod touch, making it resemble an iPhone. But the iPod touch doesn't have a virtual Click Wheel that appears on the screen. Instead, it uses the same multi-touch interface that the iPhone uses. You navigate through music, videos and other files using your fingers and the touch-sensitive screen.

The iPod touch also has a few other features that iPod enthusiasts had hoped to see on standard iPod models. Some users hoped for a wirelessly enabled iPod so they could synch their music or share files with friends over a Bluetooth or WiFi connection. The iPod touch is the first iPod to have wireless capability, although it doesn't use it to synch with a computer or friends' iPods. Instead, you can use it to browse the Web, watch YouTube videos or download music from a WiFi-specific iTunes Music Store.

With its widescreen display and WiFi capability, the iPod touch might sound like a big step up from older iPod models. But the iPod touch isn't for everyone. In this article, we'll look at how the iPod touch measures up to the iPod classic and other versions of the iPod. We'll also examine the technology behind the multi-touch interface and the media player's technical specifications.

iPod Touch Features

It's easy to think of the iPod touch as a stripped-down version of the iPhone instead of a souped-up iPod. The iPod touch is a little smaller and weighs a little less than the iPhone. But the iPod touch has a battery that lasts a little longer than the one on the iPhone. The iPhone has about 24 hours of audio or seven hours of video playback time, and the iPod touch can play 36 hours of audio or six hours of video on a full charge.

The iPod touch and the iPhone

The iPod touch's home screen also looks like the iPhone's, but with fewer icons. From the home screen, you can get to the iPhone's e-mail client, text-messaging capabilities, digital camera and collection of mini-applications called widgets. And, of course, you can also use the iPhone as a cellular phone. The iPod touch doesn't share any of these features, but the two devices do have a few things in common, including:

• Flash memory (8 or 16 GB for the iPhone, 8, 16 or 32 GB for the iPod touch)
• WiFi capabilities (802.11b/g)
• Safari Web browser
• Audio, video and photo storage and playback
• YouTube video player
• Calendar and contacts that synch with your computer
• Clock and calculator applications
• Access to the iTunes Music Store via WiFi
• Dock and headphone connections

The iPod touch also costs roughly the same amount as an iPhone or an iPod classic, but each of these devices has significantly different features and capabilities. Here's a run-down of the costs:

• iPod touch: $229 for 8 GB, $299 for 16 GB, $399 for 32 GB
  
• iPhone: $199 for 8 GB or $299 for 16 GB, plus the cost of a cell-phone service plan
• iPod classic: $249 for 120 GB
• iPod nano: $149 for 8GB, $199 for 16 GB
• iPod Shuffle: $49 for 1 GB, $69 for 2 GB [source: Apple]
  

In terms of storage space, the iPod touch is comparable to the iPhone and the iPod nano, although it also comes in a 16 GB model. It costs about the same as the iPhone, but it's significantly more expensive than the nano, which costs less than $200. The iPod touch also has far less storage space than the iPod classic, but their prices are roughly the same.

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When you buy an iPod touch, you won't necessarily get more room for music and videos than you will with other iPod models. You're essentially paying extra money for WiFi capabilities, a widescreen display and a touch-sensitive user interface. Next, we'll take a look at exactly what's behind the iPod touch's most distinctive feature.

iPod Touch and StarbucksMost WiFi-enabled devices have the ability to discover nearby wireless connections. The iPod touch and the iPhone will be able to take that discovery process one step further. At participating Starbucks locations, these devices will be able to figure out what song is playing and give users a direct link to that song at the iTunes music store. Starbucks stores in New York and Seattle will have this ability in October 2007. The next locations to feature the Starbucks-iPod connection will be Los Angeles, Chicago and the San Francisco bay area.

The iPod Touch Interface

The thing that sets the iPod touch apart from other iPod models is its touch-screen interface. When you touch the screen, the iPod's circuitry detects the presence of your finger. It keeps track of how many fingers you have on the screen and where you move them.

The iPod touch does this using a layer of capacitive material under a protective covering. You can read How Capacitors Work to learn more about them, but the basic idea involves taking advantage of the electrical properties of the human body. When you touch a capacitive surface, the amount of charge it holds changes. This is why devices like the iPod touch require you to touch them with your bare skin -- insulating materials like gloves, pens and styluses don't cause the same changes in the capacitive circuitry.

The basic process behind detecting touch

There are two possible methods the iPod touch can use to measure changes in electrical states:

• Self capacitance: Circuitry monitors changes in an array of electrodes.
• Mutual capacitance: A layer of driving lines carries current. A separate layer of sensing lines detects changes in the electrical charge when you place your finger on the screen.

Sensing circuitry in a self-capacitance screen measures changes in electrical charges. In mutual capacitance, a grid of driving lines and grid of sensing lines work together to detect electrical changes.

Regardless of which method the screen uses, you change the electrical properties of the screen every time you touch it. The iPod records this change as data, and it uses mathematical algorithms to translate the data into an understanding of where your fingers are. In the next section, we'll explore what the iPod touch does with this data and how to navigate through its features.

iPod Touch Processor

The iPod touch's processor keeps track of where you put your fingers and where they move once you've placed them on the screen. You can slide your fingers from place to place, or you can make pinching or spreading motions to zoom in and out. The iPod touch matches what your fingers are doing with what's happening on the screen:

• The iPod touch determines the shape, size and location of your finger -- or fingers -- on the screen.
• The device uses gesture software in its memory to classify your touch. It takes into account whether your fingers move and what your iPod is doing at the time.
• The processor sends instructions to the iPod touch's display, software and hardware based on the data your fingers create.

Figuring out your touch input requires the cooperation of the iPod touch's processor, operating system, hardware and software.

Here's an example. If you're using the Safari Web browser and you want to type in a URL, you touch the URL field in the browser. The capacitive layer detects your touch on the screen, and the processor and gesture software cross-reference the touch data with the application in use. The processor relays a message to the iPod touch's screen, telling it to display an image of a keyboard. The screen then detects the location of each virtual key you touch, and the screen displays the corresponding letter in the URL field. Each time you touch the screen, the process of determining what you're touching and why happens in the background, almost instantaneously.

System Requirements You can synch an iPod touch with your computer using a USB cable. In addition to a USB 2.0 port and iTunes 7.4 or later, here's what you need to do this: Mac: Mac OS X v. 10.4.10 or later PC: Windows Vista or Windows XP Home or Professional with Service Pack 2 or later [source: Apple]

The gestures themselves are fairly intuitive. To turn the iPod touch on, you press the home or sleep/wake button, then move your finger across slider that appears on screen. To press on-screen buttons, you simply touch them. You can scroll through lists of files by sweeping your finger up and down the screen. If you turn the iPod touch horizontally, you can browse music through CoverFlow, an animated display of your music's cover art. As with the iPhone, you can zoom in to pictures and Web pages by pinching your fingers together, and you can zoom out by spreading them apart.

The jury's still out on whether the iPod touch will be as popular as other iPod models. Critics point out that for a little more money people can buy an iPhone, which has more features and slightly longer battery life. Others contend that the iPod classic will continue to be a top seller, since it holds vastly more music and movies than an iPod touch can.