(near-field communication) is a short-range radio technology (like Bluetooth) that has numerous applications but is most commonly associated with mobile payments, similar to waving or tapping your iPhone on a contactless terminal at retail locations (or a compatible vending machine) to make a secure purchase. Apple Watch also uses NFC to make a digital handshake with the terminal to complete the transaction. Yep, it’s all in the wrist. This feature is part of Apple Pay, Apple’s mobile payment solution for secure cash- and cardless payments. Check out Chapter 10 for more on Apple Pay.
GPS
Except for the first Apple Watch (Series 1, from 2015), Apple Watch has an integrated GPS chip to identify its location on Earth down to a few meters of accuracy. Therefore, when coupled with mapping applications, GPS can help you see your location on a map, get directions from point A to point B, look for local businesses of interest, and more. GPS can also help with tracking fitness data when measuring steps won’t help (such as in cycling). Along with the accelerometer (discussed next), built-in heart rate sensor, and Wi-Fi, Apple Watch’s GPS can help measure distance traveled. Jog on over to Chapter 8 to learn more about the Activity and Workout apps.
Ultra Wideband (Apple Watch Series 7 only)
While there aren’t a lot of use-cases for it yet, Apple added Ultra Wideband (UWB) technology to its Apple Watch Series 7. Similar to iPhones with UWB (beginning with iPhone 11 in 2019), this feature provides more precise location and spatial awareness. As you’ll see in Chapter 10, you can unlock a compatible car without even having to hold the iPhone or Apple Watch near the door lock.
Accelerometer, gyroscope, barometric altimeter, and compass
Like other smartwatches and activity bands on the market, Apple Watch has an accelerometer that measures movement, whether you’re lifting the watch to your face to turn on the screen; lowering your wrist to decline a call; or calculating fitness activities, including steps taken (like a 21st-century pedometer), total distance traveled, time spent exercising, and estimated calories burned. Beginning with Apple Watch Series 3 (2017), the watch also has an integrated barometric altimeter for measuring elevation (counting the steps you climb or descend) as well as calculating altitude for those who ski, hike, or climb mountains. Beginning with Apple Watch Series 6, the altimeter is always on, providing all-day, real-time elevation data on your wrist.
With the Apple Watch’s accelerometer and gyroscope sensor, Apple Watch Series 4 (2018) and newer models can detect whether you’ve fallen, and you can initiate a call to emergency services (or dismiss the alert). If you’re unresponsive after 60 seconds, Apple Watch automatically places the emergency call and sends a message with your location to your emergency contacts. Note: This feature is different from speaking to a live operator if you call, as you would with a service such as Philips Lifeline, but this feature is very handy to have on your wrist nonetheless (and you have no monthly fees to worry about).
A compass has been added to Apple Watch Series 5 and Series 6 models, always pointing you north inside apps like Maps, and there’s a dedicated Compass app too. (Cue the song “Go West” by the Pet Shop Boys or the Village People first!)
Heart-rate sensor
A custom heart-rate sensor included with Apple Watch helps you in two ways.
Gauging your exercise intensity and tracking overall calorie burn: (This data is an estimation based on info you input one time, such as your height, weight, gender, and age.) Apple Watch listens to your heartbeats per minute and shows you data on the screen — if and when you call for it.
Tracking your heart rate throughout the day: Apple Watch can alert you if it detects unusually high or low heart rates — and yes, you can set the parameters if you want, even if you don’t feel symptoms. Behind the watch are multiple sensors that measure your pulse through your skin. Going beyond fitness are fun applications, such as the one that lets you share your heartbeat with someone — felt on their Apple Watch — to show you’re thinking about them. See Chapter 5 for how to share this information to your heart’s content.
Electrocardiogram
Beginning with Apple Watch Series 4 (except Apple Watch SE), all Apple Watch models include an electrical heart-rate sensor that can take an electrocardiogram (ECG) by using an ECG app; the built-in sensor and the electrodes are included in the Digital Crown button. You take an ECG reading by placing a finger on the Digital Crown while wearing Apple Watch; the reading is completed within 30 seconds. The ECG app tracks whether your heart is beating in a regular pattern or whether you have signs of atrial fibrillation — a clear indicator of serious health problems.
Blood-oxygen monitor (pulse oximeter)
Beginning with Apple Watch Series 6, your wearable device is capable of detecting blood-oxygen levels. When you tap the Apple Watch app, green, red, and infrared LEDs shine light into your wrist, and photodiodes measure the amount of light reflected back. Then advanced algorithms calculate the color of your blood, indicating the amount of oxygen present. Wow. Blood-oxygen levels between 95 and 100 percent are considered to be healthy — a lower percentage could indicate compromised heart, lung, or brain functionality — but be sure to consult your doctor. In fact, Apple stresses that the Blood Oxygen app is not intended for medical use; it’s designed for general fitness and wellness purposes.
Ambient light sensor
Finally, Apple Watch has an ambient light sensor under the glass. This sensor samples the environmental light falling on the screen and automatically adjusts the brightness up or down to improve viewing comfort so that the screen isn’t too dim or too bright, based on where you are. An ambient light sensor also helps regulate the power that the display uses, thus squeezing more battery life out of the watch.
In fact, beginning with Apple Watch Series 5, the Retina screen is always on — just dimmed — until you turn it toward your face to read the time or other info. In previous Apple Watch models, the screen goes black when you’re not looking at it, and it takes a split second to wake up and turn on when you turn it toward you.
Tapping with Apple Watch’s Haptic Feedback
You can tap Apple Watch’s screen, and guess what? It can tap you too.
Like videogame controllers that vibrate when your soldier gets shot or some smartphones and tablets that buzz slightly when you tap a letter on the virtual keyboard, Apple Watch employs haptic technology to apply light force to your skin to alert you to relevant information. Apple’s Taptic Engine is a linear actuator inside the watch that produces discreet haptic feedback.
Consider this slight vibration to be a third sense (touch), along with sight and sound, to give you information. The physical sensation of a tap tells you something, such as a warning that an important meeting is about to start, without your even having to look