Isn't it remarkable? I have more radios in my iPhone and iPad than I did in my "Ham Shack" back in the day when I was very active in the Amateur Radio service.
When Steve Jobs announced the original iPhone in 2007, he declared that it would be a Communicator, among other things. Now, almost six years later, all of our iOS devices have not one, but several "communicators" embedded within. I'm not talking about smoke signals or semaphores, though these would make interesting Kickstarter projects. Instead, it's all about communicating by way of good old fashioned "RF" – Radio Frequency.
Which combinations of radios your device has depends, of course, on which product family it belongs to (iPhone, iPad or iPod touch). For iPad, this is further subdivided based on which model - Wi-Fi only, Wi-Fi + 3G, or the most recent Wi-Fi + Cellular.
Let's look into your device and examine the different radios that serve up your voice and data communications: Wi-Fi, Bluetooth, Cellular (telephony), Cellular (data), and GPS. While we're at it, let's discuss how you can manage these.
Consider this: if you have an iPhone or a pimped-out iPad, you can have up to five radios running simultaneously. There may be any number of reasons for needing to pick-and-choose which radios to shut off – perhaps even all. Examples include reducing battery consumption and complying with restrictions imposed by arguably pedantic airlines.
When all of these radios are enabled, they consume a fair amount of power. If you need to go into battery conservation mode, you can help things by shutting down services that are not needed. For example, even though you are not actively using Wi-Fi or Bluetooth, these radios are still using energy to "listen" for signals. They may even send out a ping on occasion.
There are situations when you need to disable all radios in one fell-swoop. A special feature called Airplane Mode handles this for you. We will examine this shortly.
OK, let's get into the specifics.
It's a play on words with "Hi-Fi" – High Fidelity, it's also known as 802.11, which is a standards-based designation. WiFi radio circuitry is built into all current iOS devices. It is used for local area network data communications and almost always provides Internet connectivity via routers and other devices. This wireless data service is generally provided independently of cellular carriers. Wi-Fi services are widely available at no cost in public settings.
Go to Settings > Wi-Fi. In the Wi-Fi pane, you will see the ON/OFF master switch for Wi-Fi. You can confirm the state of your Wi-Fi radio by glancing up at the status bar where the Wi-Fi indicator icon is located on the left side.
The master switches for Wi-Fi and Bluetooth are readily accessible.
Bluetooth capability is available on all current iOS devices.This radio is used for short-distance data communications with peripherals, such as wireless headphones, speakers, keyboards, mice, etc. To the old-timers out there, think of this as the replacement for RS-232 data cables.
As hinted in the illustration above, the Bluetooth radio master switch is easily accessible now in iOS 6. It's directly beneath the Wi-Fi control. Previously, you had to dig down into the General Settings to get to the switch.
Cellular (wireless telephony)
A subscription service available on iPhone only. This is the cellphone radio that provides voice communications through wireless cellular carriers which connect you to other landline and cellular telephones worldwide.
There is no dedicated master switch for cellular telephony. Nevertheless, you will soon discover that Airplane Mode does disable cellular telephony along with other radio services.
Cellular (wireless data)
Available on iPhone and as a subscription service option on properly equipped iPad 2, iPad (3rd Generation), iPad (4th Generation), and iPad mini. This radio provides data connectivity to the wide area network (Internet) when subscribing with cellular providers. It uses the same technology as cellular telephony. Appropriately configured iOS devices will automatically and seamlessly switch between Wi-Fi networks and cellular data networks to provide ubiquitous Internet connectivity.
Understanding how to control this radio is important because its use is directly proportional to the money that falls out of your wallet. Because of data caps imposed by the wireless carriers, if you go over your monthly allotted limit as dictated by your subscription plan, you will be charged an additional fee.
For cellular data on iPhone as well as for appropriately configured iPad models, the master switch is located in Settings > General > Cellular. Note that for devices that support the newest high-speed LTE cellular data service, there is an independent switch for that service. Utilizing this switch may help in curtailing not only power consumption but data consumption as well.
With Cellular Data turned on, enabling LTE (if available) will provide a data transfer speed boost.
GPS (A-GPS or Assisted GPS)
Available on iPhones as well as all iPad models with cellular option. The GPS service is primarily used for navigation and geolocation. The GPS radio is a receiver only. Its sole function is to collect data from various GPS satellites and pass that data to apps that process it, such as Maps. The GPS radio works with the assistance of Wi-Fi and cellular data to quickly acquire the GPS satellite signal. This is why it works particularly well in otherwise poor signal conditions.
The GPS radio can be disabled by turning off Location Services which uses GPS circuitry and other technology to help determine your approximate location. Go to Settings > Privacy > Location Services.
Turning Location Services off will disable the GPS circuitry.
Finally, let's look at Airplane Mode.
Because of rules imposed by aircraft operators and various regulatory bodies, commercial airline passengers may be required to disable wireless features, ostensibly to reduce potential interference with aircraft operation. When Airplane Mode is turned on, no cellular phone, cellular data, Wi-Fi, or Bluetooth signals are emitted. GPS reception is turned off as well. When this mode is on, a small airplane icon appears in the device's status bar.
Airplane Mode is very easy to get to – it's the first item listed in the Settings pane.
Here's an obscure tidbit that many iOS device users don't know about: with Airplane Mode enabled, you can still turn on Wi-Fi and Bluetooth individually via their respective switches in Settings. Naturally, you need to check with the flight crew if this is allowed, as more and more airlines are installing in-flight Wi-Fi capabilities.
By the way, do you ever feel like you just need to shut out the noise and "get off the grid" for a while? You can easily do this by switching your device to Airplane Mode.
Knowing when and how to control your various radio systems in your iOS device will go a long way towards conserving power, trimming usage fees, and becoming a submissive airline passenger.