Smart Watch Apple Watch give a complete picture of the daily activity of the user. During the day, located on the wrist unit reads the physical load. With the help of photodiodes and light-emitting diodes with visible and infrared device accurately tracks the pulse. Watches analyze in detail the load during exercise and daily activities, offer individual goals and encourage personal achievement.
Normal pulse rate for a middle-aged man of 72 beats / min. Under the influence of stress heart rate increases. Apple Watch measures the heart rate and displays it on the wrist. It can be seen at any time using the cards Heart Rate Glance. During the day, Apple Watch produces measurement every 10 minutes. The data saved in Health. All information collected by the watch, the device allows the wearer to improve the control of the calories.
A method for measuring heartbeat Apple Watch based on the principle of photoplethysmography, which is non-invasive method of measuring the blood volume in tissues using two light sources and two photodetectors. Since red blood, it reflects red and absorbs green. In Apple Watch uses two green LEDs associated with photodetectors. Since the change in blood volume in synchronization with the heartbeat, this method allows to accurately calculate the heart rate.
Heart rate sensors can also use infrared radiation. This mode is activated when measuring the pulse time of 10 minutes. If the system does not provide the correct reading of data, Apple Watch the green LED. In any measurement method, the intensity of light reflected from the object to be detected in accordance with the fluctuations of the pulsating blood flow caused by heartbeat.
For a correct reading of the pulse to properly fix Apple Watch on hand. Watches should not be in a free state, the sensors fairly flat against the skin.