The evolution of watches: what they were taught technology
Some 30 years ago, a “wristwatch” meant a definite thing with a very limited set of functions: they showed the time and date, allowed to set alarms. Particularly advanced models could display time simultaneously in several time zones or readings of additional sensors (compass, thermometer). Attempts to make the device more functional were made earlier, but it was with some success in the mass segment that they were crowned only 3-4 years ago. From this point on, wearable devices with various capabilities and attributes literally poured into the market.
Since, according to the established tradition, watches are primarily perceived as a fashion accessory, in reviews a lot of attention is usually paid to the appearance and the final functions of the device. We propose to discuss watches and bracelets from the point of view of technology - consider what components underlie the stated functions, how they affect the experience of using devices and what miracles you should expect (or not expect) from such a gadget.
Remember, in the 90s of the last century, watches with a calculator were popular among schoolchildren. However, the buttons in them were so small that for a long time only enthusiasts used them (they probably tried to read books on button phones a la Siemens M55 later).
In modern form, the devices worn on the arm began to actively develop only after 2010. At first, on the forums, they were puzzling: they say, who needs them - they are so inconspicuous, with a limited set of functions, and even with a smartphone? But the screens of smartphones became more, as well as the curiosity of users. At the same time, computing power grew, which can be “shoved” into the form factor of the clock. Plus, manufacturers of watches and bracelets groped for the right market niche. We can say that now on the streets of large cities almost every third person has a wearable electronic gadget on his hand.
Even 20 years ago, fantastic films drew us the perspectives of personal assistant assistants on hand. In the modern world, it seems, it gradually becomes a reality.
In one form or another, the following functions are implemented in watches (or rather, in wrist gadgets that somehow resemble a classic watch by the form factor and dressing method):
In the market of gadgets now there are 2 categories of wearable devices on the arm: fitness bracelets and smart watches. However, the line between them is very conditional: many fitness bracelets show time, and smart watches count steps and calories. So we will consider them all together.
Fundamental points that must be considered when choosing such a device, three. It:
But we will pass to examples. We will not talk about design, ergonomics and interface - let's discuss the technical basis underlying this mass of functions.
Satellite navigation in smart watches exists in two variations - in the form of a stand-alone GLONASS or GPS receiver, or in the form of a map display for navigation, launched on a smartphone.
Independent GPS (GLONASS) is usually installed in devices targeted at serious athletes, as well as in children's watches with the location tracking function from a “parent” smartphone (for example, it is in hours) Life button 911
The advantage of this approach is in saving smartphone battery power, as well as the ability to work without it at all. In addition, an independent GPS (GLONASS) allows you to adjust the readings of other sensors (for example, measuring the distance traveled by the pedometer.
The main disadvantage is the short hours of operation of the clock from the built-in battery with activated reception of the signal from the satellites.
As an example of gadgets with "their" GPS (GLONASS), you can take Xiaomi Amazfit Sports Watch, Garmin Forerunner 235 or the already mentioned Sony SmartWatch 3 SWR50 Sport.
The second option is simpler. In this case, a wearable gadget is just an extra screen, which, for example, does not need to be taken out of your pocket when you walk in unpleasant weather. Support for this version of GPS is in watches running Android Wear (more on this OS, we will dwell further).
Interestingly, the option “navigation on smartphones” is also used in some “tracking” tags (for example, there is an advertisement calling for the use of such tags to control children). It is designed for accurate positioning of the child using other people's smartphones with GPS enabled, low-power Bluetooth and support for a special service of “roaming” data transmission about the location of tags that fall within the BLE coverage area of the smartphone. In our conditions, the technology is not yet very applicable, since the Crowd GPS user community is not so large that the label even in the crowd of the supermarket is always in the coverage area of at least one of the community members. Perhaps the situation will change in the future, because tags are actively sold, including in our country. Although among users, "bought" for advertising, is already maturing discontent technology. They are still waiting for her to work, as promised.
Compass - addition to satellite navigation. It can be based on GPS (or GLONASS) - then it will give adequate readings only while driving (and, taking into account the error in satellite positioning, it is necessary to move quickly). Another option is an independent magnetic compass - a digital sensor that displays one of a finite set of directions, for example, 1 out of 16, as in the well-known Casio Protrek series (which have nothing to do with the smart watch segment) or in models like the Huawei Watch 2 Sport 4G. This variant of the compass is preferred by travelers, since it does not require movement for positioning.
Usually in the watch for travelers additionally installed sensors:
They provide information about the weather and reduce the time for satellite positioning (by estimating the approximate height above sea level in terms of pressure — with such assumptions, the task of triangulation is solved faster).
Theoretically, travelers might also find useful information about humidity. But hours with this option units. As an example, you can bring out of production Microsoft Band 2.
For those who do not need sensors, but a weather forecast, it’s better not to dwell on expensive models, but to pay attention to devices that will broadcast local weather and weather forecast data for the coming hours from a smartphone on the screen (the function, in particular, is embedded in Android Wear).
The lion's share of wearable devices can notify the host of events on the head unit - a smartphone with which they are synchronized via Bluetooth.
It may be:
In some cases, devices allow you to customize notifications for other applications — for example, instant messengers or social networks. Sometimes with the help of a bracelet you can turn off the sound of a call without dropping it.
Some devices have their own microphone and speaker and allow you to view call history or answer calls.
The ability to manage notifications laid, for example, in Android Wear, and is available on some watches with their own OS.
A watch in which a stand-alone SIM card is installed can completely replace a smartphone. Among the possible applications:
The SIM-card has its own “Life Button” children's watches (and other children's devices), as well as in some completely adult models, for example, Huawei Watch 2 Sport 4G.
In contrast to the functions for travelers who have previously been built into the clock (remember at least fairly well-known Casio products), it is difficult to implement fitness functions without a head unit (smartphone) or good built-in computing power.
Physically, most of them are based on collecting evidence from just 2 sensors:
By the principle of operation, the electronic pedometer resembles a pendulum, which closes or opens the circuit when shaken. But in modern bracelets, the counting of steps (and accounting for other physical activity) is more often carried out with the help of acceleration sensors - two or three, placed perpendicularly to each other. After filtering interference, they give information about the change in the position of the arm in space.
Roughly speaking, the software of the bracelet searches the graph of accelerations (or signals from the pedometer) typical patterns embedded in it. With walking and other sports physical activity, it makes it easier for this pattern to repeat. Bracelets from different manufacturers can differently consider the steps - this is due to the fact that each developer uses their own components and sets their own patterns.
The accuracy of measurements is influenced by the ability of the firmware to filter false movements (sweeps with hands, turns on a chair; movement in vehicles, etc.). By the way, to improve the accuracy of determining the steps, it is recommended to wear a bracelet on the non-leading hand.
Some gadgets distinguish walking and running. If the device is equipped with accelerometers, and not an electronic pedometer, it can track not only “foot” exercises, but also other types of physical activity, such as swimming. In this case, some devices determine the change of activity automatically, while others need to report it manually. However, not all available wearable gadgets support a variety of physical activity.
Multiplying the number of steps obtained by the average step length gives the distance traveled in a day. Of course, it is very conditional, since Most bracelets / watches determine the step length by gender, age and height specified in the settings - i.e. they use not direct measurements, but average values.
Single models on the market (for example, the Garmin range of smart watches) are equipped with their own GPS - they consider the distance much more accurately and can record the workout track. Some Android Wear watches are able to clarify the readings on the GPS of the smartphone, but here the functionality completely depends on the installed applications, the availability of the connection, and also sometimes the internet connection.
Similar to the distance traveled, “knowing” the number of steps (and type of physical activity, if this option is available), you can get an approximate amount of calories spent. Here, also, the calculations use average data (how many calories the average person burns the average person of the same sex and age), so it’s pointless to wait for an accuracy of 1 calorie. The resulting figure is only a guide.
The pulse in most fitness bracelets and smart watches is measured using an optical sensor located on the back of the device (a window with a green LED). There are models in which the heart rate monitor is implemented in a separate case - for example, in Garmin Vivofit to improve accuracy, it is mounted on the chest (the error is not higher than 5%). In addition, there is a standardized interface for interaction with external heart rate monitors, which is supported by some wearable devices (ANT +). However, for the average user such difficulties come to nothing.
In any case, wearable devices can support both static pulse measurement and the collection of pulse data over time (for example, during training). Most manufacturers use their own models and algorithms here.
In addition to physical activity itself, sensor data allows you to collect sleep statistics. The start of sleep is usually fixed when the user does not move for about an hour. A stage is determined by the nature of hand movements. In this case, a number of models are oriented only at the acceleration sensor, while others check additionally “check themselves” with a heart rate monitor.
Accuracy is generally dependent on the algorithm embedded in the device software. For example, the Chinese bracelet No1 F1 can record 2 hours of evening work at a computer in a “dream” - despite the fact that the user, although he is sitting still, still uses the keyboard and mouse.
The very direction of tracking the activity and rest of a person in his movements exists much longer than modern fitness trackers, and actigraphy is called actigraphy (the section of physiology). Actigraphy usually deals with more medical problems — it helps diagnose various sleep disorders. Thanks to the development of computing power of personal devices, as well as algorithms for processing the collected data, actigraphy now provides quite high accuracy. And although she is still far from the polysomnography technique used for sleep analysis in scientific centers with the help of a pile of sensors connected to the patient, she can find a place even in scientific works, since Actigraphy allows measurements in a natural setting, not in a laboratory. But it is unlikely that all this can fit in inexpensive fitness bracelets.
Unfortunately, unlike counting steps and measuring distances, users can hardly check the accuracy of sleep monitoring by themselves.
Another “derivative” function, based already on sleep monitoring, is a smart alarm clock that, with the help of vibration, wakes its owner not exactly at the appointed minute, but by a specified time, taking into account the sleep phase (usually takes a period of 20 to 30 minutes before the appointed time) . The sleep phase is also determined in the same way as in monitoring (described above). Roughly speaking, he stirred - it's time to wake up.
Opinions about the performance of such alarms vary. For some, this is a good way not to get up broken in the morning. Others do not feel vibration (for example, if its level is too weak or the gadget was mistaken in determining the phase of sleep).
In terms of functions for travelers or communication tools, questions about accuracy did not arise in principle. Here, either the binary option (provided or not, such as notifications) is available, or the result of the wearable device can be checked — see the positioning accuracy, track the error in measuring atmospheric pressure, etc. With fitness functions, everything is different. It collects data that is difficult for a person to self-assess. In addition, manufacturers of smart watches and bracelets do not disclose the components of the devices themselves, as well as the algorithms underlying the calculation of various parameters. So it remains to rely on user tests and comparisons of device operation in various conditions (for example, here ).
In general, the collection of data on physical activity and their analysis are two different tasks. A typical scheme of such devices is displaying the results of direct measurements and the simplest analysis — such as calculating the distance traveled based on the step length and the number of steps — on the screen of a wearable device and simultaneously transmitting data for a deeper analysis to a smartphone (in some cases, a computer).
This division of the task generates another important parameter - the storage time of the collected data without synchronization. For example, the already mentioned Chinese F1 without connecting to a smartphone stores data for the last 7 days. In offline mode, it displays time, number of steps, distance traveled and momentary pulse. When connected to a smartphone, synchronization starts, and already the head unit is engaged in deep processing of the collected statistics to obtain information about sleep (and it does not give out the result immediately).
Thus, three components can immediately introduce errors into measurements:
Therefore, when choosing a wearable device to pay attention to fitness functions, it must be borne in mind: in addition to specialized activity trackers created by manufacturers of bracelets or watches for working with their own devices, cross-platform solutions like Google Fit or Apple Health have long existed. However, not all devices work with it (i.e. allow you to export data there). The decision on whether you need the same Google Fit will have to be made at the point of purchase.
Many, even cheap wearable devices from smartphones have migrated various interface options, which slightly increase the pleasure of using them. These “bonuses” work due to the following sensors:
The first smart watches and bracelets worked on their own closed OS from the manufacturer or on the trimmed “smart phone” Android. In rare cases, it was possible to install additional software on them, for example, from the manufacturer’s application store (as was the case with Pebble). However, in general, the range of capabilities of such devices is limited to what is incorporated in it by the manufacturer.
But everything changes. With the growing popularity of wearable devices on the hand, several OSs appeared, in particular - a separate “branch” of the Android OS, adapted to the “smart watch” - Android Wear. Now already the 2nd version is relevant. Models running Android Wear 2 are mostly equipped with a touch screen, a gyroscope and a light sensor that provides some uniformity of control. Such watches are compatible not only with Android smartphones, but also with IPhone.
Of course, there are other operating systems, for example, Tizen and watchOS. However, Android is popular with the largest number of manufacturers. TIzen in the context of wearable electronics is developed mainly by the efforts of Samsung. watchOS - Apple.
The three listed OS variety of products on the market is not limited. For example, Garmin devices exist “in their dimension,” where there is also an app store; Pebble, despite the closure, has left a whole industry of development.
Why do we need additional applications? Let's try to list the most popular additional functions (some of them may be paid):
It is worth remembering that the clock is not a smartphone; their functionality is completely limited by the screen size: it’s just inconvenient to do many things with them (and it’s also pointless if you have a smartphone). Therefore, in this case, there is no sense in pursuing a variety of third-party applications - there have not yet appeared such tools for which it would be worthwhile to look for watches only with Android Wear (or another specific OS). Waiting for future updates is also a very dubious argument. Release version 2.0 waited almost 2 years, and many even actual at the time of the release of the new version of the device did not receive an update.
The only indisputable plus of Android Wear 2.0 is the ability to use the watch in everyday mode as a separate device (without a smartphone). Although to configure and update the smartphone is still needed.
Smart watches and devices worn on the hand in general are a fairly new market (if you do not take into account the long-existing iPods and smartphone cases on the forearm). However, even during the short life of the market, several rather exotic ideas had time to manifest themselves here (some of them have already safely disappeared).
Idea 1 - use E-Ink / E-Paper screen or its equivalent to save battery. The brightest representative was the Pebble startup, which, unfortunately, closed at the end of 2016. Another interesting option is the Qualcomm Toq with the Mirasol color electrophoretic screen.
Idea 2 is to equip devices with a camera (sometimes with the ability to shoot video), a slot for a memory card and other options for an “adult” smartphone.
Idea 3 - to use round screens to stylize a regular watch. Representatives of this segment just do not disappear anywhere.
The idea of 4 is to embed a mass of sensors - UV radiation, moisture, galvanic skin reaction for a more in-depth analysis of what is happening (the Microsoft Band and its second version, Microsoft Band, were surprised by the abundance of sensors, but alas, both devices left the market).
On the market there are also actively developing watches with an analog interface (ordinary watches equipped with additional sensors). It is difficult to say exactly how they should be classified - as a smart watch with a different screen or as a fitness bracelet with additional functions.
Above almost nothing is said about battery life, but this is an important factor that I want to take into account when choosing. But here, in general, everything is clear. This time increases if in the device:
For fitness bracelets, work from several days to months is considered the norm, for a smart watch a good indicator is a couple of days.
Many wearable devices support magnetic or wireless charging - this is most relevant for gadgets with a short battery life.
Another option - protection from dust and moisture. It provides standardization for IP or WR. But do not blindly trust the declared parameters, because:
— . , , .
Since, according to the established tradition, watches are primarily perceived as a fashion accessory, in reviews a lot of attention is usually paid to the appearance and the final functions of the device. We propose to discuss watches and bracelets from the point of view of technology - consider what components underlie the stated functions, how they affect the experience of using devices and what miracles you should expect (or not expect) from such a gadget.
Remember, in the 90s of the last century, watches with a calculator were popular among schoolchildren. However, the buttons in them were so small that for a long time only enthusiasts used them (they probably tried to read books on button phones a la Siemens M55 later).
In modern form, the devices worn on the arm began to actively develop only after 2010. At first, on the forums, they were puzzling: they say, who needs them - they are so inconspicuous, with a limited set of functions, and even with a smartphone? But the screens of smartphones became more, as well as the curiosity of users. At the same time, computing power grew, which can be “shoved” into the form factor of the clock. Plus, manufacturers of watches and bracelets groped for the right market niche. We can say that now on the streets of large cities almost every third person has a wearable electronic gadget on his hand.
What features survived the evolution?
Even 20 years ago, fantastic films drew us the perspectives of personal assistant assistants on hand. In the modern world, it seems, it gradually becomes a reality.
In one form or another, the following functions are implemented in watches (or rather, in wrist gadgets that somehow resemble a classic watch by the form factor and dressing method):
- directly hours - display of time in one or several time zones, date, alarm clocks), as well as a stopwatch and timer. Often time synchronization with a cellular network or a head unit (smartphone) is supported. Interestingly, there are still anachronisms without synchronization on the market (for example, the Chinese Noname bracelet watch with notifications using vibration);
- calendar - current date, calendar (sometimes with reminders); in models for travelers sometimes there are schedules of sunrises and sunsets;
- traveler's tools - compass, weather sensors (thermometer - for ambient air, barometer), altimeter;
- GPS or GLONASS navigation ;
- notifications from the head unit - a smartphone (the connection is most often made via low-power Bluetooth - BLE). Hours can notify on calls / messages, as well as on any other events in the smartphone applications. Some only send a signal, while others allow you to get the subscriber number or message text;
- headset - the answer to calls and messages on the head unit;
- simple smartphone - support for installing a separate SIM card for calls and messages, even if by a limited list of numbers, as in a children's clock (for example, in the 911 Life button);
- fitness functions : pedometer, pulse sensor, blood pressure or body temperature measurement, sleep monitoring. In a separate category, you can select "smart" alarm clock, which does not work exactly in time, but in a certain interval, taking into account the sleep phase. Some bracelets additionally record the parameters of other physical activities - running, swimming, etc. In principle, some devices can monitor the daily calorie - however, the “weight” of products or, at a minimum, the user must manually add their names.
- full OS and applications from the corresponding store - audio player, calendar, weather, etc .;
- interface functions - changing the brightness of the screen depending on the lighting, gesture control, device search, control of the head unit functions (camera, presentations and music player);
- in addition : support for ANT + (data transmission technology used mainly in sports equipment), the ability to connect external sensors via Bluetooth for low power consumption, NFC (for quick connection to smartphones, for example, Sony SmartWatch 3 SWR50 Sport).
In the market of gadgets now there are 2 categories of wearable devices on the arm: fitness bracelets and smart watches. However, the line between them is very conditional: many fitness bracelets show time, and smart watches count steps and calories. So we will consider them all together.
Fundamental points that must be considered when choosing such a device, three. It:
- screen availability;
- ability to work independently (without a head unit) at least in the mode of time display and step counting;
- the ability to extend the functionality through the installation of applications (from the store of the manufacturer or OS).
But we will pass to examples. We will not talk about design, ergonomics and interface - let's discuss the technical basis underlying this mass of functions.
Functions for travelers
Navigation
Satellite navigation in smart watches exists in two variations - in the form of a stand-alone GLONASS or GPS receiver, or in the form of a map display for navigation, launched on a smartphone.
Independent GPS (GLONASS) is usually installed in devices targeted at serious athletes, as well as in children's watches with the location tracking function from a “parent” smartphone (for example, it is in hours) Life button 911
The advantage of this approach is in saving smartphone battery power, as well as the ability to work without it at all. In addition, an independent GPS (GLONASS) allows you to adjust the readings of other sensors (for example, measuring the distance traveled by the pedometer.
The main disadvantage is the short hours of operation of the clock from the built-in battery with activated reception of the signal from the satellites.
As an example of gadgets with "their" GPS (GLONASS), you can take Xiaomi Amazfit Sports Watch, Garmin Forerunner 235 or the already mentioned Sony SmartWatch 3 SWR50 Sport.
The second option is simpler. In this case, a wearable gadget is just an extra screen, which, for example, does not need to be taken out of your pocket when you walk in unpleasant weather. Support for this version of GPS is in watches running Android Wear (more on this OS, we will dwell further).
Interestingly, the option “navigation on smartphones” is also used in some “tracking” tags (for example, there is an advertisement calling for the use of such tags to control children). It is designed for accurate positioning of the child using other people's smartphones with GPS enabled, low-power Bluetooth and support for a special service of “roaming” data transmission about the location of tags that fall within the BLE coverage area of the smartphone. In our conditions, the technology is not yet very applicable, since the Crowd GPS user community is not so large that the label even in the crowd of the supermarket is always in the coverage area of at least one of the community members. Perhaps the situation will change in the future, because tags are actively sold, including in our country. Although among users, "bought" for advertising, is already maturing discontent technology. They are still waiting for her to work, as promised.
Compass
Compass - addition to satellite navigation. It can be based on GPS (or GLONASS) - then it will give adequate readings only while driving (and, taking into account the error in satellite positioning, it is necessary to move quickly). Another option is an independent magnetic compass - a digital sensor that displays one of a finite set of directions, for example, 1 out of 16, as in the well-known Casio Protrek series (which have nothing to do with the smart watch segment) or in models like the Huawei Watch 2 Sport 4G. This variant of the compass is preferred by travelers, since it does not require movement for positioning.
Weather
Usually in the watch for travelers additionally installed sensors:
- air temperature
- atmospheric pressure.
They provide information about the weather and reduce the time for satellite positioning (by estimating the approximate height above sea level in terms of pressure — with such assumptions, the task of triangulation is solved faster).
Theoretically, travelers might also find useful information about humidity. But hours with this option units. As an example, you can bring out of production Microsoft Band 2.
For those who do not need sensors, but a weather forecast, it’s better not to dwell on expensive models, but to pay attention to devices that will broadcast local weather and weather forecast data for the coming hours from a smartphone on the screen (the function, in particular, is embedded in Android Wear).
Communicator
Notifications
The lion's share of wearable devices can notify the host of events on the head unit - a smartphone with which they are synchronized via Bluetooth.
It may be:
- LED vibration or blinking - when you receive calls or SMS-messages;
- Vibration with the display of the number (name) of the caller.
In some cases, devices allow you to customize notifications for other applications — for example, instant messengers or social networks. Sometimes with the help of a bracelet you can turn off the sound of a call without dropping it.
Some devices have their own microphone and speaker and allow you to view call history or answer calls.
The ability to manage notifications laid, for example, in Android Wear, and is available on some watches with their own OS.
Smartphone on hand
A watch in which a stand-alone SIM card is installed can completely replace a smartphone. Among the possible applications:
- emergency communication with a pre-set number (for example, SOS for the elderly and children);
- quick response to calls and messages;
- communication tool for short runs or walks with children when there is no place to put a smartphone with a large screen.
The SIM-card has its own “Life Button” children's watches (and other children's devices), as well as in some completely adult models, for example, Huawei Watch 2 Sport 4G.
Fitness opportunities
In contrast to the functions for travelers who have previously been built into the clock (remember at least fairly well-known Casio products), it is difficult to implement fitness functions without a head unit (smartphone) or good built-in computing power.
Physically, most of them are based on collecting evidence from just 2 sensors:
- heart rate monitor;
- electronic pedometer or a set of accelerometers in various spatial directions.
Pedometer
By the principle of operation, the electronic pedometer resembles a pendulum, which closes or opens the circuit when shaken. But in modern bracelets, the counting of steps (and accounting for other physical activity) is more often carried out with the help of acceleration sensors - two or three, placed perpendicularly to each other. After filtering interference, they give information about the change in the position of the arm in space.
Roughly speaking, the software of the bracelet searches the graph of accelerations (or signals from the pedometer) typical patterns embedded in it. With walking and other sports physical activity, it makes it easier for this pattern to repeat. Bracelets from different manufacturers can differently consider the steps - this is due to the fact that each developer uses their own components and sets their own patterns.
The accuracy of measurements is influenced by the ability of the firmware to filter false movements (sweeps with hands, turns on a chair; movement in vehicles, etc.). By the way, to improve the accuracy of determining the steps, it is recommended to wear a bracelet on the non-leading hand.
Some gadgets distinguish walking and running. If the device is equipped with accelerometers, and not an electronic pedometer, it can track not only “foot” exercises, but also other types of physical activity, such as swimming. In this case, some devices determine the change of activity automatically, while others need to report it manually. However, not all available wearable gadgets support a variety of physical activity.
Multiplying the number of steps obtained by the average step length gives the distance traveled in a day. Of course, it is very conditional, since Most bracelets / watches determine the step length by gender, age and height specified in the settings - i.e. they use not direct measurements, but average values.
Single models on the market (for example, the Garmin range of smart watches) are equipped with their own GPS - they consider the distance much more accurately and can record the workout track. Some Android Wear watches are able to clarify the readings on the GPS of the smartphone, but here the functionality completely depends on the installed applications, the availability of the connection, and also sometimes the internet connection.
Similar to the distance traveled, “knowing” the number of steps (and type of physical activity, if this option is available), you can get an approximate amount of calories spent. Here, also, the calculations use average data (how many calories the average person burns the average person of the same sex and age), so it’s pointless to wait for an accuracy of 1 calorie. The resulting figure is only a guide.
Heart rate
The pulse in most fitness bracelets and smart watches is measured using an optical sensor located on the back of the device (a window with a green LED). There are models in which the heart rate monitor is implemented in a separate case - for example, in Garmin Vivofit to improve accuracy, it is mounted on the chest (the error is not higher than 5%). In addition, there is a standardized interface for interaction with external heart rate monitors, which is supported by some wearable devices (ANT +). However, for the average user such difficulties come to nothing.
In any case, wearable devices can support both static pulse measurement and the collection of pulse data over time (for example, during training). Most manufacturers use their own models and algorithms here.
Sleep monitoring
In addition to physical activity itself, sensor data allows you to collect sleep statistics. The start of sleep is usually fixed when the user does not move for about an hour. A stage is determined by the nature of hand movements. In this case, a number of models are oriented only at the acceleration sensor, while others check additionally “check themselves” with a heart rate monitor.
Accuracy is generally dependent on the algorithm embedded in the device software. For example, the Chinese bracelet No1 F1 can record 2 hours of evening work at a computer in a “dream” - despite the fact that the user, although he is sitting still, still uses the keyboard and mouse.
The very direction of tracking the activity and rest of a person in his movements exists much longer than modern fitness trackers, and actigraphy is called actigraphy (the section of physiology). Actigraphy usually deals with more medical problems — it helps diagnose various sleep disorders. Thanks to the development of computing power of personal devices, as well as algorithms for processing the collected data, actigraphy now provides quite high accuracy. And although she is still far from the polysomnography technique used for sleep analysis in scientific centers with the help of a pile of sensors connected to the patient, she can find a place even in scientific works, since Actigraphy allows measurements in a natural setting, not in a laboratory. But it is unlikely that all this can fit in inexpensive fitness bracelets.
Unfortunately, unlike counting steps and measuring distances, users can hardly check the accuracy of sleep monitoring by themselves.
Smart alarm clock
Another “derivative” function, based already on sleep monitoring, is a smart alarm clock that, with the help of vibration, wakes its owner not exactly at the appointed minute, but by a specified time, taking into account the sleep phase (usually takes a period of 20 to 30 minutes before the appointed time) . The sleep phase is also determined in the same way as in monitoring (described above). Roughly speaking, he stirred - it's time to wake up.
Opinions about the performance of such alarms vary. For some, this is a good way not to get up broken in the morning. Others do not feel vibration (for example, if its level is too weak or the gadget was mistaken in determining the phase of sleep).
And what is the accuracy?
In terms of functions for travelers or communication tools, questions about accuracy did not arise in principle. Here, either the binary option (provided or not, such as notifications) is available, or the result of the wearable device can be checked — see the positioning accuracy, track the error in measuring atmospheric pressure, etc. With fitness functions, everything is different. It collects data that is difficult for a person to self-assess. In addition, manufacturers of smart watches and bracelets do not disclose the components of the devices themselves, as well as the algorithms underlying the calculation of various parameters. So it remains to rely on user tests and comparisons of device operation in various conditions (for example, here ).
In general, the collection of data on physical activity and their analysis are two different tasks. A typical scheme of such devices is displaying the results of direct measurements and the simplest analysis — such as calculating the distance traveled based on the step length and the number of steps — on the screen of a wearable device and simultaneously transmitting data for a deeper analysis to a smartphone (in some cases, a computer).
This division of the task generates another important parameter - the storage time of the collected data without synchronization. For example, the already mentioned Chinese F1 without connecting to a smartphone stores data for the last 7 days. In offline mode, it displays time, number of steps, distance traveled and momentary pulse. When connected to a smartphone, synchronization starts, and already the head unit is engaged in deep processing of the collected statistics to obtain information about sleep (and it does not give out the result immediately).
Thus, three components can immediately introduce errors into measurements:
- the sensors themselves;
- Device software;
- and software for in-depth analysis on a smartphone.
Therefore, when choosing a wearable device to pay attention to fitness functions, it must be borne in mind: in addition to specialized activity trackers created by manufacturers of bracelets or watches for working with their own devices, cross-platform solutions like Google Fit or Apple Health have long existed. However, not all devices work with it (i.e. allow you to export data there). The decision on whether you need the same Google Fit will have to be made at the point of purchase.
Interface
Many, even cheap wearable devices from smartphones have migrated various interface options, which slightly increase the pleasure of using them. These “bonuses” work due to the following sensors:
- lighting (by analogy with smartphones, this sensor allows you to control the brightness of the screen, muting it in the dark). Theoretically, the light sensor can be used in the implementation of fitness functions, but the manufacturers do not directly talk about the collection of such data;
- gyro (for controlling gestures; the most popular application is to turn on the screen when the user puts his hand to his eyes to watch the time, other gestures en masse, unfortunately, have not yet taken root).
- microphone (for voice control on those models where it is available).
OS and applications
The first smart watches and bracelets worked on their own closed OS from the manufacturer or on the trimmed “smart phone” Android. In rare cases, it was possible to install additional software on them, for example, from the manufacturer’s application store (as was the case with Pebble). However, in general, the range of capabilities of such devices is limited to what is incorporated in it by the manufacturer.
But everything changes. With the growing popularity of wearable devices on the hand, several OSs appeared, in particular - a separate “branch” of the Android OS, adapted to the “smart watch” - Android Wear. Now already the 2nd version is relevant. Models running Android Wear 2 are mostly equipped with a touch screen, a gyroscope and a light sensor that provides some uniformity of control. Such watches are compatible not only with Android smartphones, but also with IPhone.
Of course, there are other operating systems, for example, Tizen and watchOS. However, Android is popular with the largest number of manufacturers. TIzen in the context of wearable electronics is developed mainly by the efforts of Samsung. watchOS - Apple.
The three listed OS variety of products on the market is not limited. For example, Garmin devices exist “in their dimension,” where there is also an app store; Pebble, despite the closure, has left a whole industry of development.
Why do we need additional applications? Let's try to list the most popular additional functions (some of them may be paid):
- more advanced hours (time in different time zones, stopwatch, alarm clock);
- control of the clock interface (dials, themes and shell);
- voice assistant (for this, a microphone must be placed in the clock, the clock is connected to the smartphone, and the smartphone, in turn, is connected to the Internet to process the voice command);
- management of applications on the smartphone (camera, player, contacts, call);
- notifications from the smartphone (about calls and messages with indication of the number / name of the subscriber, sometimes - display of the message text);
- weather;
- Advanced tracking of physical activity (data processing of embedded sensors, sending data via a smartphone to the cloud, etc.);
- entertainment (simple games, watching videos and photos);
- clients to applications on the smartphone, performing part of their functions.
It is worth remembering that the clock is not a smartphone; their functionality is completely limited by the screen size: it’s just inconvenient to do many things with them (and it’s also pointless if you have a smartphone). Therefore, in this case, there is no sense in pursuing a variety of third-party applications - there have not yet appeared such tools for which it would be worthwhile to look for watches only with Android Wear (or another specific OS). Waiting for future updates is also a very dubious argument. Release version 2.0 waited almost 2 years, and many even actual at the time of the release of the new version of the device did not receive an update.
The only indisputable plus of Android Wear 2.0 is the ability to use the watch in everyday mode as a separate device (without a smartphone). Although to configure and update the smartphone is still needed.
Exotic
Smart watches and devices worn on the hand in general are a fairly new market (if you do not take into account the long-existing iPods and smartphone cases on the forearm). However, even during the short life of the market, several rather exotic ideas had time to manifest themselves here (some of them have already safely disappeared).
Idea 1 - use E-Ink / E-Paper screen or its equivalent to save battery. The brightest representative was the Pebble startup, which, unfortunately, closed at the end of 2016. Another interesting option is the Qualcomm Toq with the Mirasol color electrophoretic screen.
Idea 2 is to equip devices with a camera (sometimes with the ability to shoot video), a slot for a memory card and other options for an “adult” smartphone.
Idea 3 - to use round screens to stylize a regular watch. Representatives of this segment just do not disappear anywhere.
The idea of 4 is to embed a mass of sensors - UV radiation, moisture, galvanic skin reaction for a more in-depth analysis of what is happening (the Microsoft Band and its second version, Microsoft Band, were surprised by the abundance of sensors, but alas, both devices left the market).
On the market there are also actively developing watches with an analog interface (ordinary watches equipped with additional sensors). It is difficult to say exactly how they should be classified - as a smart watch with a different screen or as a fitness bracelet with additional functions.
About battery life and protection
Above almost nothing is said about battery life, but this is an important factor that I want to take into account when choosing. But here, in general, everything is clear. This time increases if in the device:
- large battery;
- few features that require a processor;
- the screen is smaller and simpler (the backlight is weaker, the more energy-saving technologies at the hardware level);
- better thought out energy saving plan.
For fitness bracelets, work from several days to months is considered the norm, for a smart watch a good indicator is a couple of days.
Many wearable devices support magnetic or wireless charging - this is most relevant for gadgets with a short battery life.
Another option - protection from dust and moisture. It provides standardization for IP or WR. But do not blindly trust the declared parameters, because:
- most often these figures are obtained on test samples. Perhaps with a margin. But how real they are in practice depends on the build quality. For example, it suffices to slightly twist the rubber seal during assembly, and the device will no longer withstand the declared water pressure;
- Microphones, connectors and other openings should also not allow water to enter the device. Such technologies exist, but any components in the “waterproof” version are more expensive. . , IP68, (, - , )?
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