Everything related to data logging or detection is tied to the sensors built into the smartwatch. Without in-depth understanding, many people will think that the heart rate and pedometer sensors are the same.
There are three main types of sensors in smartwatches: acceleration sensors, ECG sensors, and GPS sensors, and the other is an ultraviolet sensor that has only been released in recent years. They can record different data. Next, let's take a look at the characteristics of the following sensors.
1. Acceleration sensor
Acceleration sensors are the most common type of sensor in smartwatches, and they are commonly used for step counting. By measuring the direction of action and the speed of the swing, the acceleration sensor can determine whether the device is in a vertical or horizontal position and whether it is in a moving state, so as to achieve the purpose of step counting.
Of course, not all acceleration sensors are accurate. The basic model has only two axes, which is relatively inaccurate; while the three-axis sensor can better detect the position of the device in three-dimensional space and achieve more accurate recording.
It is suitable for indoor and outdoor pedometer use, is not affected by weather, consumes less power, and can store sports data for several days. However, for some low-profile acceleration sensors, the number of steps can be generated by shaking hands or swinging the arm in place, which affects the accuracy of motion data.
2. ECG sensor
The ECG sensor is directly linked to heart rate monitoring and is a highly professional sensor. This kind of sensor judges the user's heart rate by measuring the electrical signal of myocardial contraction, and the principle is similar to that of an electrocardiogram. Although they have high accuracy, they also have the disadvantage that the circuit is more complicated and is easily interfered by electromagnetic waves. And it is placed in a fixed measurement position, otherwise, the results will be biased.
There is another detection method that belongs to the same ECG sensor, that is, the photoelectric type. The photoelectric heart rate uses the photo volume method, shining a light on the wrist, and then measuring the light scattering of different blood flow rates. It's less accurate than a heart rate belt, but it's less hassle and effort to wear.
3. Satellite sensor
Any and all GPS-related devices need to be connected through satellites, so the smartwatches with GPS functions also have built-in satellite sensors.
They calculate the distance traveled per unit time by receiving signals from extraterrestrial satellites, and calculate the speed of movement. The accuracy of the position signal is determined by the strength of the satellite signal and the sampling rate. The shorter the sampling time, the higher the sampling rate.
Although GPS causes the battery to drain too fast, it can record the track of the movement and synchronize it to the map, which involves the professional-grade star search function. If you need to use it to record outdoor running, the star search ability can best be completed within 10s to ensure the efficient accuracy of the journey. For daily navigation assistance, the search time can be relaxed to the 30s.
4. UV sensor
The ambient light sensor simulates the sensitivity of human glasses to light, can judge the time according to the brightness of the surrounding light, and effectively save the power consumption of the motion monitoring equipment. The UV sensor borrows this principle and can be used on the watch to monitor the UV index in the light and realize the sunscreen reminder operation.
If you need to use it as a stylish watch, its professional heart rate monitoring function is often just an embellishment. Most of the functions used by users may be to watch the time, push text messages, record steps, etc. At this time, you only need to choose a watch with an acceleration sensor or a UV sensor type.
If it is used as a sports watch, in addition to the need to record the path of the exercise, the heart rate cannot be ignored, and the heart rate needs to be monitored in real-time. Therefore, it is better to choose smartwatches with ECG sensors and satellite sensors.
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