Comparison Xiaomi Redmi Watch 4 vs Xiaomi Watch 2 Pro

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.

The operating system installed on the gadget itself.

In this case, we do not mean basic firmware, but rather a full-fledged OS that provides extensive capabilities. For example, allowing you to install additional applications or functionally tailored for close integration with certain web services. The most popular operating system options for wrist gadgets are presented below:

– Android. The Android mobile OS is known mainly for smartphones and tablets, but its open source code allows it to be optimized for other devices, including wrist devices. Note that traditional Android applications are generally poorly compatible with wrist gadgets, but some programs are able to automatically adapt to such devices, and specialized software is also produced for certain models (often by the manufacturers themselves).

– WatchOS. An operating system specially designed for Apple wrist gadgets and used only in them. Among the key features, it is worth noting support for the Siri voice assistant and the Apple Pay system, a set of fitness tools, as well as a high degree of optimization for Apple Watch controls. WatchOS uses its own applications, which can also be created by third-party developers.

– Wear OS. The system formerly known as Android Wear. This is a specific version of Android, originally developed as a solution for “smart” wrist gadgets. It features a radically redes...igned interface, close integration with the Google Assistant voice assistant, and so-called proactive notifications. Thanks to the latter, the device is able to independently, without a request, issue extended tips for a certain situation: for example, before an important meeting, plot a route on the map taking into account traffic jams and, if necessary, turn on a reminder earlier than the originally planned time.

— Nucleus. Quite a rare and unusual “OS”: it does not belong to a general-purpose OS, but to real-time systems. Such systems are optimized for the fastest possible response to external events (whereas in conventional operating systems the reaction occurs depending on the distribution of resources). Specifically, Nucleus has all the capabilities necessary for wrist gadgets, however, for a number of reasons, such firmware is quite rare.

— Tizen. An open operating system for mobile devices, primarily promoted by Samsung. As with Android, the original Tizen is poorly suited for smartwatches, so we usually talk about a special version of Tizen Wearable. It is worth noting that there are tools that allow you to run Android applications on devices running this OS.

– ColorOS. A system developed by OPPO and used in its mobile devices. Directly for smart watches, the operating system is presented in the form of ColorOS Watch - the system interface is optimized for use on small screens and includes tools for tracking the user’s physical activity, monitoring sleep and health, managing notifications, etc. Moreover, smartwatches powered by ColorOS Watch can serve as a digital key for some modern Chinese-made cars.

– HarmonyOS. Huawei's universal operating system, also known as Hongmeng. Provides operation of a wide range of devices: equipment from the smart home ecosystem, smart watches, smartphones and tablets. Onboard wearables, HarmonyOS is a redesigned version of the homegrown Lite OS used in Huawei watches and other low-end devices.

– Zepp OS. A specialized real-time system for Amazfit and Zepp smartwatches. It is an open platform for health management and activity tracking, based on the principles of ease, fluidity and practicality. One notable feature of the OS is support for cloud Internet service applications (like Spotify, SoundCloud, etc.).

– Lite OS. A lightweight system for wearable gadgets with limited computing power, used in some simple smartwatch models from Huawei. A more advanced version of the operating system for such devices from the manufacturer is HarmonyOS (see above).

– Fitbit OS. An operating system developed for Fitbit wrist gadgets and used only in them. Fitbit OS supports the installation of various applications on smart watches, the system implements gesture control, and many widgets and watch faces have been released for it. The operating system also provides targeted exercise modes and the possibility of contactless payment for purchases in stores using the NFC chip of the watch using the Fitbit Pay program.

– Moto Watch OS. Proprietary software for Motorola smart watches from the category of real-time systems. Moto Watch OS is designed with an eye toward accurate health tracking, the OS also collects information about user activity, supports receiving notifications from a connected smartphone, and ensures maximum battery life for the wearable gadget. Note that the operating system does not support installing applications from third-party developers - you will have to be content with pre-installed tools and programs.

– MagicOS. An operating system specially designed for Honor wrist gadgets and used only in them. In appearance and in terms of its set of capabilities, it is very similar to the related operating system HarmonyOS, which is found in Huawei wearable devices. It is argued that MagicOS has its own philosophy and development vector.

– BlueOS. Vivo's own OS, which can run a wide range of devices - from mobile phones and tablets to smart watches. In fact, the system’s debut took place on board wearable gadgets in 2023. The “operating system” is written in the Rust programming language with an emphasis on maximum protection of user data. A distinctive feature of BlueOS is generative artificial intelligence. Thus, Vivo smart watches have already implemented the function of creating dials by voice with the participation of AI.

– HyperOS. A unified Linux-based operating system for Xiaomi smart devices. But if in mobile phones HyperOS has replaced the proprietary MIUI shell, then in the smartwatch segment this is something new. The emphasis in Xiaomi's operating system is on the close interconnection of all devices running HyperOS within a single ecosystem.

Types of notifications, as well as basic voice communication features supported by the gadget.

- Notifications. In classic smart watches and fitness trackers, the specific functionality of such notifications can be different – from a regular sound or vibration signal to the ability to display on the screen and even respond. But in any case, such notifications are often more noticeable to the user than the own signal from a smartphone located deep in a pocket or bag.

— Voice control. The ability to control the device through voice commands. In order for a smartwatch or fitness tracker to perform some simple feature, it is enough to say its name aloud.

— Voice assistant. In watches with voice assistant support, the level of user interaction with the device is displayed in a new qualitative way. The most popular virtual assistants are Google Assistant and Amazon Alexa. In Apple devices, the role of an assistant is performed by Apple Siri, in Samsung wearable gadgets — a virtual assistant Bixby. Unlike the voice control function, the assistant does not just turn on this or that feature, but allows you to perform certain operations in applications that require feedback.

— Sound signal. The ability to give sound signals using the built-in speaker. This feature will be useful primarily in situations where the gadget is not on hand — for example, if it is used as an ala...rm clock and is removed at night.

— Vibration. Vibration signal similar to that used in mobile phones. In wearable gadgets, such a signal is especially convenient due to the fact that the device is constantly in contact with the wearer's skin, so that the vibration is perfectly felt — and regardless of the level of noise around. In addition, vibration mode is also useful in quiet environments where a loud sound signal is undesirable.

— Built-in microphone. Own microphone built into the body of the device. Such equipment can be used for different purposes, depending on the type and features of the gadget. First of all, voice communication is impossible without a microphone. Another feature for which a microphone is required is the voice assistant (see above). And in children's smartwatches, it may be possible to remotely turn on the microphone from the parent gadget and listen to what is happening around the child; see the relevant paragraph below for details.

— Speakerphone(speaker). The ability to work the gadget in hands-free mode, using the built-in speaker and microphone for conversation. In a conventional smartwatch (see "Type"), this feature allows you to talk through the watch without removing the smartphone from your pocket; in watch-phones, speakerphone allows you to do so without headphones and headsets, and for children's smartwatches, this feature is almost mandatory. However the volume of the built-in speaker is usually low, so in a noisy environment its power may not be enough.

This block contains both various navigation systems ( GPS, Galileo) and auxiliary features for them ( aGPS, GPS tracking, maps, compass, altimeter , barometer). More about them:

— GPS module. GPS satellite navigation module built right into the watch/tracker. The initial purpose of such a module is to determine the current geographic coordinates; but how this information will be used depends on the specific type and model of the gadget. For example, in some devices GPS is used only for measuring the distance traveled and/or speed of movement, while more advanced models support full navigation and are equipped with built-in maps. In addition, this feature is almost mandatory in children's beacons (see "Type") — it is GPS that is responsible for determining the location of the child.

— aGPS. An auxiliary feature that allows you to speed up the start of the main GPS receiver. To work for its main purpose, such a receiver must update data on the location of navigation satellites; Obtaining this data in the classical way, directly from the satellites themselves, can take quite a long time (up to several minutes). This is especially true for the so-called "cold start" — when the receiver starts up after a long break in opera...tion, and the data stored in it has become completely outdated. aGPS (Assisted GPS) allows you to receive up-to-date service information from a mobile operator — from the nearest base station (this feature is supported by most operators nowadays). This can greatly speed up the startup process.

— GLONASS. This system is a Russian alternative to the American GPS. However it provides somewhat less accuracy, so GLONASS support is usually provided in addition to the GPS module. Simultaneous use of two systems, in turn, improves positioning accuracy.

— Galileo. European satellite navigation system, created as an alternative to the American GPS. Note that it is under the control of civilian departments, not the military. With a full fleet of 24 active satellites, the system gives an accuracy of up to 1 m in public mode and up to 20 cm with the GHA service. Working in conjunction with GPS, the Galileo system provides a more accurate position measurement, especially in densely populated areas.

— Maps. The feature of displaying topographic maps of the area with heights, relief and types of vegetation on the clock screen. Preinstalled maps are used for visual GPS navigation without being tied to a smartphone. Often, the ability to display maps is implemented in tactical smartwatches with a focus on tourism.

— GPS tracking. Many watches with the possibility of laying routes have the feature of guiding by the GPS track. At the same time, the wearable gadget acts as a navigator around the area, showing the route on the screen and suggesting where it is necessary to turn in one direction or another. Some smartwatches with a pronounced touristic bias also have a “Return Route” programme that allows you to go back along an already traveled route. In GPS tracker mode, trackpoints are usually recorded automatically based on the selected fixing interval. You can also mark a track point manually at any time.

— Compass. A classic compass is a device that indicates the direction to the cardinal points. Wearable gadgets usually use an electronic compass — a miniature magnetic sensor, the data from which, if necessary, are displayed on the display.

— Altimeter. A feature that allows you to determine the current altitude of the user's location. Note that the principle and format of the altimeter may be different. So, some models use barometer data for height measurements, others use information from a GPS sensor; the height itself can be determined relative to sea level, relative to some reference point, or in any of these ways, at the choice of the user. These details should be clarified separately.

— Barometer. A feature that allows you to determine the current atmospheric pressure. One of the applications of the barometer is weather forecasting: for example, a sharp drop in pressure usually signals the approach of bad weather. In addition, information from this sensor can be used to operate the altimeter (see above); and even if the gadget does not have an altimeter, the height difference between two points on the ground can be easily calculated from the pressure difference between them.

The size of the display installed in the gadget; for round screens, respectively, the diameter is indicated.

A larger screen, on the one hand, is more convenient to use, on the other hand, it significantly affects the dimensions of the entire device, which is especially critical for wearable gadgets. Therefore, manufacturers choose the display size in accordance with the purpose and functionality of each specific model — so that there is enough space on the screen and the device itself is not too bulky.

It is also worth mentioning that screens with a similar size may have different aspect ratios. For example, traditional smartwatches are usually equipped with square or round panels, while in fitness trackers, screens are often made elongated in height.

Screen size in dots (pixels) horizontally and vertically. In general, this is one of the indicators that determine the image quality: the higher the resolution, the clearer and smoother the picture on the screen (with the same size), the less noticeable are the individual dots. On the other hand, an increase in the number of pixels affects the cost of displays, their power consumption and requirements for a hardware platform (more powerful hardware is required, which itself will cost more). In addition, the specifics of using smartwatches is such that there is simply no need to install high-resolution screens in them. Therefore, modern wrist accessories use displays with a relatively low resolution: for example, 320x320 with a size of about 1.6" is considered quite sufficient even for premium watches.

The density of dots on the screen of the gadget, namely, the number of pixels that are on each inch of the panel vertically or horizontally.

The higher the PPI, the higher the detail of the screen, the clearer and smoother the image is. On the other hand, this indicator affects the price accordingly. Therefore, the higher the density of points, the more advanced, usually, this gadget is in terms of general capabilities. However, when choosing a screen, manufacturers take into account the general purpose and functionality of the device; so that even a small number of PPIs usually does not interfere with comfortable use.

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 model name of the processor (CPU) installed in the watch. Knowing this name, you can find detailed data on a particular CPU and evaluate its level and general capabilities. This is especially important due of the fact that these capabilities depend not only on the basic specs (number of cores, clock frequency), but also on specific design nuances.