What Is a Digital Compass in an iPhone?

by Adrian Grahams Google

    The Apple iPhone includes many navigation and location features that can help you find your way in unfamiliar neighborhoods, including an advanced Compass application that uses the iPhone's integrated digital compass technology to tell you which way your iPhone is facing in real time. The Compass app looks and feels just like a traditional magnetic-needle compass, and it's just as easy to use as an old-style compass because it rotates on the screen to match the direction you’re facing.

    How the iPhone's Digital Compass Works

    The Apple iPhone harnesses two internal devices to operate the digital compass -- a magnetometer that measures changes in the Earth's magnetic field and an accelerometer that tracks the movement of the device. The iPhone's Compass app combines the heading information from the magnetometer with the roll and pitch data from the accelerometer to work out the exact orientation of the iPhone as you move the device. For certain functions, such as longitude and latitude location data, the Compass app also uses the iPhone's integrated GPS technology.

    Using the iPhone's Digital Compass

    The iPhone's digital compass application works just like any magnetic-needle compass. Launch the application by tapping the "Compass" button on the iPhone's home screen. Once activated, the compass displays the current orientation of the iPhone in degrees as a digital readout below an arrow icon at the top of the screen. Below this, the main part of the screen shows the same information in graphical compass format with directional arrows. To travel in a particular direction, move the iPhone until the correct directional arrow on the compass lines up with the main arrow icon at the top of the screen and move in that direction. The bottom of the screen shows your exact position on the Earth's surface in longitude and latitude, which is useful if you want to find your precise position on a map or satellite navigation system.

    Understanding True North and Magnetic North

    The compass application includes a "True North" and "Magnetic North" setting that you can access by tapping the "i" button at the bottom of the main compass screen. Magnetic north moves slightly, depending on the local strength of the Earth's magnetic field. The angle of difference between magnetic north, and true north is called declination and this angle changes depending on where you are on the Earth's surface. In most cases, select the default "True North" setting on the iPhone compass application for accurate navigation.

    Calibrating the iPhone Compass

    Interference and magnetic fields from nearby electronic devices or magnets, including the magnets in the earpiece of iPhone headphones, can affect the accuracy of the Compass app. The app displays a calibration alert when interference is causing a problem. To troubleshoot interference and calibrate the compass, rotate the iPhone in a figure-eight motion until the alert disappears. You may need to move away from any potential source of interference and repeat this process to overcome the problem and remove the alert. The iPhone prompts you to calibrate the compass the first time you launch the application.

    Third-Party iPhone Digital Compass Apps

    The Compass app comes as a standard feature on the Apple iPhone, but you can also download free and paid compass apps from the App Store on your iPhone. The premium Compass+ app offers six graphical compass display themes with Retina graphics. It also offers a location-tagging feature that allows the user to tag a location and then get directions back to the tagged location. The free Digital Compass for iPhone app is a reliable free alternative to Compass+, displaying latitude and longitude information and your directional heading on the main screen. The premium 3D Compass for iPhone4 app offers all the directional features of a standard compass application, but it also displays your exact position in a 3D ball graphic.

    About the Author

    Adrian Grahams began writing professionally in 1989 after training as a newspaper reporter. His work has been published online and in various newspapers, including "The Cornish Times" and "The Sunday Independent." Grahams specializes in technology and communications. He holds a Bachelor of Science, postgraduate diplomas in journalism and website design and is studying for an MBA.

    Photo Credits

    • Kiyoshi Ota/Getty Images News/Getty Images