Comparison Smart Watch Smart GT08 vs Smart Watch Smart DZ09

The main way to connect a wearable gadget with external devices. For smartwatches and fitness bands (see "Type"), this refers to a connection to a smartphone or tablet, while in the case of watch-phones, it usually refers to headsets.

— Bluetooth. Wireless technology for direct communication of various devices with each other. This is the most popular interface in smartwatches and bracelets: Bluetooth modules can be made very tiny, the communication range even in the earliest versions reaches 10 m, and different generations of Bluetooth are mutually compatible in terms of basic functionality. Specifically, the versions nowadays are as follows:

• v2.0. The earliest standard used in modern wearable gadgets. The possibilities of such a connection are more modest than those of more advanced versions, but they are often quite enough.
• v3.0. A standard that combines classic Bluetooth v 2.0 and a high-speed “add-on” for transferring large amounts of data.
• v4.0. Further, after 3.0, improvement of Bluetooth: in addition to the classic and high-speed format, this version added Bluetooth Low Energy technology. Support of this technology is especially useful in fitness trackers, which usually transmit small amounts of data, but constantly.
• v4.1. Modification of the 4.0 standard described above with improved protection against interference while working with LTE mobile communications. ...i> v4.2. Another improvement of the 4.0 standard, which introduced, in particular, improved data protection and increased connection speed.
• — v 5. The fifth generation of Bluetooth was released in 2016. The key innovation in version 5.0 was the expansion of capabilities related to the Internet of Things. Thus, in the Bluetooth Low Energy protocol, it became possible to double the data transfer rate (up to 2 Mbit/s) at the cost of reducing the range, and also quadruple the range at the cost of reducing the speed; In addition, a number of improvements have been introduced regarding simultaneous work with a large number of connected devices.
• — v 5.1. Update of the version described above v 5.0. In addition to general improvements in the quality and reliability of communication, this update introduced such an interesting feature as determining the direction from which the Bluetooth signal is coming. This makes it possible to determine the location of connected devices with centimeter accuracy.
• —v 5.2. The next, after 5.1, is the fifth generation Bluetooth update. The main innovations in this version are a number of security improvements, additional optimization of power consumption in LE mode and a new audio signal format for synchronizing parallel playback on multiple devices.
• —v 5.3. The Bluetooth v 5.3 wireless communication protocol was introduced at the dawn of 2022. Among the innovations in it, they accelerated the process of negotiating a communication channel between the controller and the device, implemented the function of quickly switching between the operating state in a low duty cycle and a high-speed mode, and improved the throughput and stability of the connection by reducing susceptibility to interference. When unexpected interference occurs in Low Energy mode, the procedure for selecting a communication channel to switch from now on has been accelerated. There are no fundamental innovations in protocol 5.3, but a number of qualitative improvements are evident in it.
  
  Of course, to use all the capabilities of a particular version of Bluetooth, it must be supported not only by the gadget itself, but also by the smartphone/tablet to which it is connected.

Types of sports and medical data collected by the gadget (plus some features of a similar purpose, such as sleep tracking, smart alarms, stress levels and women's calendar). Note that the features from this list can be found not only in specialized fitness trackers (see "Type"), but also in more traditional devices like smartwatches. Here are the most popular options:

— Pulse rate. Heart rate is one of the most important physiological parameters of a person. So that sports training is as effective as possible, the heart rate must be in a certain range (the specific value depends on the purpose of the training and the personal data of the user). And for some illnesses and treatments, a faster or slower heart rate can be an important signal, including a warning of danger.

— Pressure (tonometer). A sensor that measures the user's blood pressure. Note that the accuracy of such a sensor is usually quite low, the measurement error can be 10% or even more; so it will not replace a full-fledged medical tonometer. On the other hand, a gadget with this feature is quite capable of detecting a critical increase or decrease in pressure, which will allow you to take the necessary measures in a timely manner.

— ECG. A sen...sor that allows you to get detailed data about the work of the user's heart. Note that such a sensor is not a full-fledged electrocardiograph — in fact, it is an advanced type of heart rate monitor that can track the features of the heart rhythm. However, even this is enough to detect some dangerous phenomena — for example, atrial fibrillation, which at first is imperceptible to a person — and take appropriate measures in time.

— The blood oxygen. A sensor (the so-called pulse oximeter) that determines the saturation of the blood with oxygen (saturation); at the same time, the measurement is carried out by a non-invasive method — without punctures and other damage to the skin. Like most medical sensors in wearable gadgets, it is not accurate and is not a full-fledged medical device, but it is quite capable of responding to a critical decrease in the level of oxygen in the blood. It is believed that the presence of a pulse oximeter is relevant primarily for certain diseases, when saturation may decrease due to the disease itself or the characteristics of the treatment being taken. However, this feature can also be useful for quite healthy users who often travel at high altitudes — primarily climbers and aeronauts.

— Body temperature. The presence of a sensor for measuring temperature allows you to take measurements without the use of thermometers. Naturally, errors can occur, so a slight deviation from the norm may not be determined, but the device will easily fix a significant increase in temperature.

— T° of the environment. Even though smartwatches are worn on the body, the built-in sensors in them are usually designed to measure the ambient temperature. This information can be useful both for a general assessment of the surrounding conditions, and for specific purposes — in particular, weather forecasting. It is not uncommon for watches with this feature to also have a barometer (see "Navigation").

— Number of steps. The traditional pedometer is a feature for counting the number of steps taken by the user. These measurements usually use data from the accelerometer, and the results are quite accurate: most modern accelerometers are well calibrated and are quite capable of distinguishing tremors during steps from hand waves and other extraneous movements. The exception is trips in land transport: many wearable gadgets perceive shaking as steps, which should be taken into account when evaluating the results.

— Distance travelled. Measurement of the total distance traveled by the user. For this, either data from a pedometer or a GPS module are usually used (see "Navigation"); each option has its own merits. So, the pedometer is cheaper, it can be used even in rooms without windows, where the signal from satellites does not reach, and on simulators like treadmills, where the user does not move relative to the ground. GPS, in turn, gives higher accuracy, especially over long distances, and is not prone to false positives in vehicles. In some advanced gadgets, these methods can be combined — this is not cheap, but it allows you to combine the advantages of both options and achieve maximum accuracy.

— Movement speed. Determining the speed of the user's movement. As with distance travelled, measurement can be done in a variety of ways; see above for more details. Also note here that many gadgets with this feature are able not only to determine the current speed, but also to constantly record its value and display various indicators: the maximum achieved speed, the average value for training, etc.

— Energy spent (calories). Measurement of the number of calories burned by the user in the process of movement. These data are rather approximate, as they are calculated by indirect parameters (speed and range of movement, personal specs of a person, etc.). However, even this accuracy is quite enough to determine the overall effectiveness of training.

— The amount of fat burned. Measuring the amount of fat burned per workout. As in the case of calories (see above), the result of such measurements is quite approximate. However, in fact, absolute accuracy is not required, and fat loss data can be a powerful motivator.

— Activity time. A measurement of the total time during which the user is actively moving. In many models, such metering may provide additional options, such as fixing several periods of activity with breaks between them and determining the ratio between the time of movement and the time of rest.

— Smart alarm. An alarm clock that monitors the user's sleep phases and gives a signal to wake up at the optimal time for this. Human sleep consists of alternating phases, and waking up in the unfortunate phase creates a feeling of lethargy and fatigue, even if there was enough time to sleep. A smart alarm clock avoids such situations; its work is based on tracking the pulse, breathing rate and other parameters that differ depending on the phase of sleep. Note that the deviation of the signal from the set time can be up to half an hour, but this is usually a deviation towards an earlier rise. As a result, the risk of being late with a smart alarm clock is close to zero, and the lack of sleep time is compensated by the optimal moment of awakening.

— Sleep tracking. Sleep quality assessment is based on data from on-board sensors of fitness trackers or smartwatches. In particular, the heart rate monitor controls the number of contractions of the heart muscle, the accelerometer controls the user's movements. A blood oxygen sensor, if available on the wearable, improves the accuracy of sleep quality data collection. According to the readings of the sensors, the moments of entering and exiting the deep sleep phase are recorded. It is during this period that the restoration of the nervous system and the accumulation of energy for the coming day take place. In deep sleep, a person can completely reboot and gain strength, while in REM sleep, brain activity practically does not differ from the state of wakefulness. The sleep quality analysis feature helps you determine the best time to go to sleep and provides personalized recommendations to improve your night's sleep.

— The level of stress. The level of stress of the body allows you to evaluate the metric that determines the variability of the heartbeat — the difference in time between successive contractions of the heart muscle. Respiration rate, maximum oxygen consumption and excess oxygen consumption after exercise are also taken into account. The stress level score gives a clear picture of the user's experience during the day, however, the value of this parameter is in determining the most optimal body regimen for training. A high heart rate variability usually indicates you are in good shape for playing sports, while a low one can indicate fatigue, dehydration, or feeling unwell. All this directly affects the ability to train effectively. There are no clear units for measuring the level of stress — in smartwatches, the parameter is usually shown as a scale from 0 to 100, often indicating the number of hours the body is under stress and the time it takes to recover to a normal state.

— Women's calendar. The tool for tracking the menstrual cycle keeps abreast of the events of the expected dates of the menstrual period, allows you to determine the most favorable days for conception, helps to notice alarming symptoms in time and prevent many diseases in case of cycle disorders. Based on your total cycle length, the device calculates a predicted date for your next period. The women's calendar records cycle dates, fertility windows, and the day of ovulation. By adding your own notes to it, you can track fluctuations in sleep, appetite, fitness, mood changes and predict well-being for a particular day.

In addition to those described above, more specific types of measurements can be found in modern wearable gadgets.

Bezel-less are displays in which the case or bezel does not occupy the usable area of the front panel, or it is minimized. In terms of design, bezels have both pros and cons. One of the most important reasons for adding substantial bezels to your screen is physical protection. The bezel-less display is very easy to scratch or damage when dropped. On the other hand, the frame takes up space on the screen, and this is one of the reasons why the frames in modern smartwatches are minimized, making the gadget more compact and stylish.

The type of battery that is installed in the watch/bracelet.

— Li-Ion (lithium-ion). Battery of the original format, made using Li-Ion technology. Such batteries combine compact dimensions with good capacity, they are unpretentious in use, durable and reliable, and among the significant drawbacks, one can only note some sensitivity to low temperatures. As a result, this technology is one of the most popular in modern portable electronics, including wearable accessories.

— Li-Pol (lithium polymer). An updated and improved version of Li-Ion technology (see above). With the same basic advantages, lithium-polymer cells have even greater capacity with the same small dimensions and weight, they hold voltage more stable as they are discharged and are more resistant to low temperatures. At the same time, these batteries are somewhat more expensive.

— Battery. Powered by a replaceable battery — usually a compact "tablet" of one type or another. Such batteries have a relatively low capacity and are usually made disposable, that is, they cannot be recharged. Therefore, such power is found mainly among two categories of devices: in fitness trackers without a display, as well as watches of a classic design with a minimum of smart features that do not require a lot of energy.

The capacity of the battery that is installed in the gadget.

Theoretically, the higher the capacity, the longer the battery can work on a single charge. However, in fact, the battery life of the gadget also depends on its power consumption, and it is determined by the specs of the display and the hardware. Therefore, only models of the same type with very similar specs can be compared in terms of battery capacity; and for an accurate assessment of battery life, it is better to focus on the directly claimed operating time in one mode or another (see below).

It is also worth mentioning that high-capacity batteries inevitably turn out to be quite heavy and bulky. So the capacity of batteries installed in wearable gadgets is also greatly limited by size and weight.

Battery life is the number of hours during which the gadget can stay afloat on a single battery charge in normal use.

Normal mode, as a rule, means working with a relatively low load. At this time, the display can display some data, basic functions can also work (counting steps, periodically checking heart rate, etc.), but in any case, power consumption is low. The declared operating time in hours is indicated for wearable gadgets that operate on a full battery charge for up to 72 hours (3 days). These are all “Apple” smart watches from Apple, many models of children’s “smart” watches, etc. For more autonomous models, operating time is indicated in days (see “Operating time (normal mode, days)”). When choosing based on this indicator, it also doesn’t hurt to pay attention to the declared battery life in active mode (see below) - especially if a long operating time is critical, or you plan to use the gadget intensively. The actual autonomy of the device will most likely be somewhere in between these two values, depending on the actual load. If only the time in normal mode is indicated for the gadget, you should choose with a certain reserve.

The time that the gadget is able to work on one charge of the battery in the active mode of use.

For watch-phones (see “Type”), this usually means a talk mode, for other gadgets, an intensive work mode when numerous features and sensors are used and there is a constant exchange of data with a smartphone/tablet. However, the specific understanding of the "active mode" for different manufacturers may vary: some indicate the time at maximum performance (that is, in fact, guaranteed battery life), others — in some kind of "average mode". However, anyway, this is a fairly clear parameter that describes the battery life of a particular model quite well (and is much closer to real indicators than the time in normal mode mentioned above).

Note that for models with a GPS sensor (see "Navigation"), the specifications may additionally specify the time of active operation using such a sensor. See "Operating time (GPS)" for details.

The material from which the body of the gadget is made. Some models are available in several versions, made of different materials — for example, aluminium or steel; for such cases, all available options are indicated in the specs at once.

— Plastic. Plastic is often considered a low-cost option, but this is not true in the case of wearable gadgets: such devices can use different types of plastic, including very advanced, durable and reliable ones. So the overall quality of such a case, usually, directly depends on the price category of the device. The common advantages of all types of plastic are relatively low weight, resistance to moisture, the ability to give the body any colour and shape, as well as low thermal conductivity.

— Metal. Cases made of metal, for which the manufacturer, for some reason, did not specify the specific composition. However, most often in such cases we are talking about aluminium or steel, see below for more details on both. But high-end materials such as gold or titanium are rarely hidden under the modest term "metal" — they are usually indicated directly in the specifications. Anyway, in general, metal cases are somewhat stronger and more reliable than plastic ones, they also look more solid, but they are also more expens...ive.

— Steel. Usually, stainless steel is used for wearable gadgets. It is highly durable and reliable, does not corrode, looks stylish and neat, and is relatively inexpensive — cheaper than many aluminium alloys, not to mention titanium. One of the peculiarities of steel cases is rather heavy weight, but it can be both a disadvantage and an advantage: a massive case creates an additional feeling of reliability and solidity. It should be noted that most gadgets with steel cases have round dials and a traditional design, which is well suited even to a business style, but occasionally there are exceptions.

— Aluminium. Aluminium alloys combine high strength and low weight — much less than steel. But this material is somewhat more expensive. It is also considered well suited for bright youth gadgets, although it is occasionally used in more traditional devices.

— Rubber. A material found in some models of children's beacons and fitness trackers (see "Type"), but almost never used in other types of wearable gadgets. One of the key advantages of rubber is softness, which gives a certain degree of impact protection and makes the case as safe as possible; both are especially important for children's devices. In addition, such a case can be easily made waterproof and even completely sealed, as well as made in any colour. On the other hand, plastic has practically the same advantages (except for softness), and rubber costs a little more (although it is noticeably cheaper than metals).

— Titanium. Titanium alloys are premium materials and are rarely used, mainly in top-tier models of “extreme” gadgets. This material is light and at the same time extremely durable, besides it perfectly holds its shape when struck; however, titanium costs much more than the same aluminium, despite the fact that high reliability is not so often decisive.

— Gold. Gold or gold-plated case turns the gadget into a stylish fashion accessory. Such a case is very expensive, but this cannot be called a disadvantage: the price of the device emphasizes the status of the owner.

— Ceramics. Special high-strength ceramics is another premium material that not only performs a practical function, but also demonstrates the high level of the gadget and the solidity of its owner. On the practical side, in addition to strength and reliability, this material has extremely high scratch resistance, which allows it to retain its looks for a very long time even in not very favorable conditions. At the same time, ceramics do not tolerate strong point impacts.

The type of clasp used on a gadget's strap or bracelet.

The most common types of clasps today are the classic buckle, folding clip, folding lock, magnet, snap fastener, and Hook-and-loop. If several options are indicated in the specs at once, it means that the gadget is supplied or can be supplied with different strap options using different types of fasteners. Here is a detailed description of each type:

– Classic (with buckle). Clasp resembling a belt buckle; originally used in traditional wristwatches, but nowadays it has become widespread in smart gadgets. On one half of such a fastener there is a U-shaped or similar frame with a special pin, on the second — a row of holes. When fastening, the second half is threaded through the frame, and the pin is fixed in one of the holes. At the same time, by choosing a particular hole, you can adjust the size of the strap. In addition, the advantages of the classics are reliability, neat appearance and compatibility with many strap materials (with the exception of metal bracelets).

— Clip (unfolding). An option for metal bracelets. The most widespread type of clip, consisting of two curved plates connected by an axis. When unfastened, they open like a book, increasing the overall length of the bracelet and allowing you to easily r...emove the watch from your hand, and when fastened, they fold close to each other and are fixed, securing the bracelet on your wrist. Another, less popular variety is the “butterfly”, which has two flaps that, when opened, rise like wings. In general, the clips are very easy to use, but difficult to set up. They fasten and unfasten with literally one click, but it’s impossible to reconfigure the size of a bracelet with a clip “on the go” — you have to disconnect and reconnect special latches, which requires an additional tool and some skill.

— Magnetic. A fastener in which a strong permanent magnet plays the role of a latch. Such devices are simple and convenient both in use and in adjustment: for fastening and unfastening, it is enough to “stick” or “unstick” a magnet, and size adjustment is carried out right at the time of fastening — by tightening the strap to the desired length. The main disadvantage of such a clasp is that it can only be used with metal bracelets made of magnetic alloys — for example, steel.

— With lock. A clasp that resembles the buckle described above, but has a slightly different principle of operation. On one side of the strap with such a clasp there is a latch pin, on the other side there is a loop of a D-shaped or other shape, as well as a number of holes. When fastening, the side with the pin is threaded into the loop and then fixed in one of the holes; By choosing one or another hole, you can adjust the length of the strap. This design is especially suitable for rubber straps, it is simpler and at the same time more reliable than the buckle, which can also be used with such straps.

— Hook-and-loop. Classic hook-and-loop closure, used exclusively with fabric straps. Like magnetic clasps (see above), such clasps allow you to very accurately adjust the length of the strap right in the process of fastening. Among the disadvantages of Hook-and-loop, in addition to restrictions on the materials of the strap, it is worth noting the tendency to reduce reliability as it wears out. Therefore, nowadays, this type of fastener is quite rare, and is almost never used as the only one available — usually Hook-and-loop is supplemented with another option, for example, a latch.

— Folding lock. Clasp in the form of a detachable lock, the halves of which are on different halves of the bracelet. It is used with finely woven metal bracelets, the so-called "Milanese" ones; at the same time, one half is fixed motionless, and the second can move along its part of the bracelet — in this way the length is adjusted. A tool may be required for adjustment, but the procedure itself is simple — much easier than with clips. And the low prevalence of folding locks is mainly due to the fact that Milanese bracelets are rarely found in smart wearable gadgets.