iPhone SE refuses to receive LTE in Russia. What is the reason?

Device manufacturer company.

Device name.

Other model names, if available. Sometimes the model is called differently, depending on the country or because of popular nicknames.

The horizontal side of the device when used in standard orientation.

The vertical side of the device when used in standard orientation.

The cross-sectional size of the device.

How much does the device weigh excluding the case, SIM and memory cards and other additional elements.

Approximate value calculated using the formula: length times width times height.

What colors is the device available in?

What materials is the body made of?

A single-chip system that contains components such as a processor, graphics accelerator, memory units, communication interfaces, etc., as well as software for the operation of the system.

The main component of the device is responsible for calculations and data processing.

What technological process is used to make the chip? The smaller the process technology, the better - the chips consume less power and generate less heat.

Processor capacity is a parameter that indicates how many bits of data a processor register processes in 1 clock cycle. This is usually 32 or 64 bits.

Instruction set architecture (ISA) is a programmable part of the microprocessor core used by software to control the operation of the processor.

The processor can be either single-core or multi-core. The performance of the processor depends on the number of cores (threads). The more cores working simultaneously, the higher the power consumption, so in mobile devices all cores are used only under high load.

Clock speed is the number of operations per second that a processor or its core can achieve. The higher the frequency, the higher the overall performance of the device, but performance also depends on the processor architecture and the number of cores.

The graphics processing unit (GPU) is used to process and display graphics - 3D effects, games, interfaces and other visual elements. Due to the pipeline architecture, the GPU is many times more efficient in graphics processing than the processor.

Similar to a processor, a GPU can have one core or several. The number of cores (threads) determines the performance and amount of information processed. The more cores, the better.

RAM (Random Access Memory, RAM, RAM) is temporary memory (works only while the device is running), which stores data and code for the operational operation of programs and applications. The more RAM, the more programs you can run simultaneously without loss of performance (there will be fewer “brakes”).

Information about the type of RAM used by the device.

The higher the amount of built-in memory, the more games, programs, music, videos and your other files will fit in the device, especially the amount of memory is important when the device does not support memory cards.

The operating system installed by default by the device manufacturer, as well as its version.

The main characteristic of a battery is its maximum capacity, that is, the charge it can store. Capacity is measured in mAh (mAh, milliamp-hour). The higher the capacity, the longer the mobile device can work.

Many types of batteries have been used in portable devices, but NiCd (nickel-cadmium), NiMH (nickel-metal hydride), and even more so SLA (lead-acid) batteries are already considered obsolete. Instead, modern mobile devices use Li-Ion (lithium-ion) and Li-Pol, Li-Poly (lithium-polymer) batteries.

About how long a fully charged battery will be discharged during a call on third generation networks. Approximate time because it is influenced by various factors, including ambient temperature.

About how long a fully charged battery will be discharged if the mobile device is in standby mode and connected to third generation networks.

The technology used to make the screen. There are many types of display manufacturing with their pros and cons.

The screen diagonal of a device is measured in inches (inch, in or simply ″), and 1″ is equal to 2.54 cm.

Approximate screen width

Approximate screen height

Aspect ratio is the ratio of the shorter side of the screen, which is considered to be 1, to the longer side, which is denoted by a decimal fraction indicating the ratio to the short side.

Screen resolution is the number of horizontal pixels (dots) multiplied by the number of vertical pixels. The higher the resolution, the more detailed the image will be.

The number of pixels per inch or PPI (pixels per inch) indicates the density of pixels per 1 inch (2.54 cm) of the screen. The higher the PPI, the sharper the image, and the less visible or even invisible “squares and dots” (pixels).

Color depth means how many bits are used in 1 pixel to display color (bits per pixel).

Approximate usable area occupied by the screen on the front of the device. The higher the percentage, the narrower the frames around the display or the smaller the “chin with bangs.”

A touch screen is a device that usually covers the display and is a touch input tool. In fact, in mobile devices, the touchscreen is a replacement for the keyboard and mouse.

There are many types of touch screens, with their pros and cons. Mobile devices often use capacitive touchscreens, but technology does not stand still and new types of sensors are appearing.

Touch screen support for two or more touches. For example, zooming photos with two fingers.

The screen and touchscreen of a mobile device are usually covered with protective tempered glass (sometimes plastic or film is used instead of glass) to protect the display from impacts and scratches. Many companies are engaged in the production of such protection, but the most famous are Corning - Gorilla Glass and Asahi - Dragontrail.

Contrast ratio is the ratio of display brightness in the white area to the black area. For example, 1000:1 means that white is 1000 times brighter than black. The higher the ratio, the deeper the blacks and the overall better image.

Screen brightness is measured in candelas per square meter (cd/m2, cd/m2). The higher this indicator, the brighter the screen luminosity will be and the less it will be affected by ambient lighting. Comfortable brightness for videos and games is considered to be 300 cd/m2 or more.

An image sensor (matrix) is a light-sensitive sensor that converts an optical image into electrical signals that the device can subsequently process.

This is the maximum number of pixels (dots) horizontally and vertically. The higher the resolution, the more detailed the image will be. Resolution can also be indicated in megapixels - this is the total number of pixels that can be in the image, calculated by the formula: vertical pixels multiplied by the number of horizontal pixels and divide the resulting amount by 1 million.

There are two main types of photomatrix, CCD (Charge-Coupled Device) and CMOS (Complimentary Metal-Oxide Semiconductor). Mobile devices mainly use a CMOS matrix - it requires less space, has low power consumption and heating. Recently, new types of sensors have begun to appear, for example PureCel from OmniVision.

The larger the physical dimensions of the sensor, the larger pixels can be installed there or the greater their number, increasing the luminous flux and exposure. That is, the larger the size, the better.

Pixel size is one of the matrix parameters that determines what size pixels are used in the matrix. The larger the size, the better - less noise and a larger light-sensitive area.

The crop factor is the ratio between the dimensions of a small format 35 mm matrix (36 x 24mm) and the size of the device matrix. That is, how much is our matrix smaller than the 35 mm matrix. Almost all cameras have smaller matrices, and the indicator itself is more of a reference value.

Focal length is the distance from the center of the lens to the image sensor.

Aperture (f-number, f) is used to control the light flux passing through the lens. The aperture is indicated by a fraction, and the smaller the fractional number, the higher the aperture passing through the lens. The more light that passes through the lens, the better overall, less noise in your photos and better night photography.

Most mobile devices are equipped with light-emitting diode (LED) flashes, but there are also xenon flashes. As a flash, xenon is better - it is more powerful, but LED is more versatile (can work as a flashlight) and consumes less electricity.

This is the maximum number of pixels (dots) horizontally and vertically. The higher the resolution, the more detailed the image will be.

FPS (Frames per Second, frame rate) is the number of frames that changes in 1 second. The higher the number of frames per second, the smoother the image will be. In this case, we mean the number of frames that the camera can achieve at its maximum resolution; the lower the resolution, the higher the FPS can be.

Incorporating a flash into a mobile device allows you to take pictures in low light conditions. Creates the necessary lighting and compensates for the lack of natural light.

With digital zoom (zoom, enlargement), the subject is brought closer due to software image algorithms. The higher the magnification with digital zoom, the worse the image quality (noise, blur) will be compared to a non-zoomed one.

This is the number of optical elements (lenses) that are contained in the optical circuit of a camera lens.

Function of auto-detection of living objects and autofocus on their face or head.

Panoramic photography is a series of frames where each subsequent frame is a continuation of the previous one; at the end of the shooting, all frames are stitched together at the software level to create a panoramic photograph. Frames can be shot both vertically and horizontally, and their width can be up to 360 degrees. This type of shooting is used when the camera's viewing angle is not enough to capture the entire scene.

HDR photography takes a quick series of shots with highlights, midtones, and shadows, then combines them into a single frame with high dynamic range.

EIS (Electronic Image Stabilizer - digital image stabilization) is performed using software algorithms and is needed to reduce blurring when the camera shakes.

Additional information about the functions and characteristics of cameras.

A matrix (sensor) is a light-sensitive element that converts an optical image into electrical signals, which the device can subsequently process. Typically, the front camera uses a simpler matrix than the main one, excluding smartphones designed for selfies.

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There are not many types of matrices, the main ones are CCD, PureCel and the most popular in mobile devices due to low power consumption and compact size - CMOS.

An aperture (or aperture) is essentially an adjustable baffle to control the amount of light passing through the lens. The aperture is indicated by a fraction, and the smaller it is, the more light passes through the lens, which has a positive effect on photographs - there will be less noise and better night photography. While the main cameras also come with an adjustable aperture, most front cameras have a fixed aperture.

This is the maximum resolution the camera can record video at. The higher the resolution, the better.

This is talking about FPS at maximum video resolution; at lower resolutions, the frame rate per second can be higher. FPS determines the smoothness of the video, as well as the ability to speed up or slow down it.

A regular (mini SIM) card has dimensions of 25x15 mm. Micro SIM - 15x12 mm. Nano SIM - 12.3x8.8 mm. The sizes of SIM cards are different and not interchangeable. There is also an eSIM (virtual, electronic SIM card), it is built into the device and does not take up space.

How many SIM cards does the device support?

GSM (Global System for Mobile Communications) is a standard for digital mobile cellular communications of the second generation 2G with time and frequency division of channels. GSM came to replace analog cellular communications 1G (first generation).

CDMA (Code Division Multiple Access) - this mobile communication standard can be classified as a 2.5G network (generation), unlike 2G, CDMA has higher speech quality, higher cellular network capacity and increased data transfer speed.

TD-SCDMA (Time Division Synchronous Code Division Multiple Access) is a third generation (3G) mobile communications standard used in China.

UMTS (Universal Mobile Telecommunications System), also called 3GSM, is a third generation (3G) mobile communications standard based on the WCDMA air interface.

LTE (Long-Term Evolution, often referred to as 4G LTE) is a standard for wireless high-speed data transmission, which, although it belongs to fourth generation networks (4G), is essentially a transitional stage from 3G to 4G, greatly accelerating data transfer speeds. The standard has an improved version, LTE Advanced (LTE-A), which can already be considered a full-fledged 4th generation network.

CDMA2000 (Code Division Multiple Access) is a third generation (3G) mobile communications standard that is based on CDMA to improve it. Compared to CDMA One, it is distinguished by network reliability, data transfer speed and high voice quality.

Technologies for receiving and transmitting data, as well as their maximum speed.

A hotspot is a Wi-Fi access point. In a mobile device, Hot-Spot turns the smartphone into a Wi-Fi access point, essentially turning it into a router capable of distributing the Internet.

DUAL-BAND (dual-band) Wi-Fi is the ability of a device to immediately receive or broadcast wireless signals in two frequency bands 2.4 and 5 GHz. 5GHz is a less congested frequency, due to which the connection will be of better quality.

MIMO is a spatial encoding method for a signal that increases the bandwidth of the channel in which data is transmitted and received by systems from multiple antennas. It is usually denoted as number (number of transmitters) x number (number of antennas). For example, 2x2 MIMO means that a WI-FI system consists of 2 transmitters and 2 receive antennas, while 1x1 is a traditional single antenna design. The more systems, the higher the throughput.

Supported WIFI wireless network standards.

Bluetooth technology is actively developing and, since 1998, has been constantly updating versions of the standard. Each subsequent version introduces one or several improvements in data exchange speed, range, facilitates pairing, reduces power consumption, or introduces some new protocols and operating profiles. The higher the Bluetooth version, the better. The technology is also backward compatible, for example, if your mobile device has version 5.0, then it will work with accessories version 4.2 and lower, but the improvements introduced in version 5.0 will not work; they will work only if both the device and accessories are version 5.

Bluetooth LE is a low energy BT protocol specification.

The A2DP Bluetooth profile is designed to transmit a high-quality two-channel stereo signal via Bluetooth to wireless headphones, speakers and other acoustics.

The light sensor reacts to the light level and is able to adjust the screen brightness automatically based on this. This is necessary to reduce power consumption and ease of use of the device.

The proximity sensor reacts to the proximity of the mobile device to some object. For example, the sensor is used when talking on the phone to turn off the screen, which saves energy and prevents you from pressing buttons with your ear or cheek.

Gyroscope (gyroscope, gyro sensor) is a sensor for orientation in space that tracks the angle of inclination of even a stationary device along three coordinate axes. The sensor is mainly used in conjunction with an accelerometer in games and applications.

An accelerometer is a sensor that measures apparent acceleration, that is, it determines the position and distance at which a mobile device moves in space. Based on the data from this sensor, the screen orientation change, pedometer, control using tilts and gestures in games and applications, etc. work.

The scanner is responsible for authorization using a previously saved fingerprint, as a result of which the device is unlocked, payment is made, some action is confirmed - just put your finger on the scanner. Scanners can be either built into the body or built into a button or screen.

This is software that displays data from a magnetic sensor or GPS in the form of a compass on the screen of a mobile device. If there are no sensors or GPS, then the digital compass will not work.

There are two types of speakers in mobile devices - auditory and musical. The auditory speaker (speaker) is used for conversation, the music speaker (buzzer) is used to play music and sounds.

Is a radio tuner integrated into the mobile device?

GPS (Global Positioning System) is a global satellite navigation system that can determine the position of a mobile device, build routes and find the desired object on the map with an accuracy of several meters.

A-GPS (Assisted GPS) is an assistive technology that will help you quickly find the location of your cellular device without waiting for satellite data, which is especially important in indoors and cities. Location is determined in various ways, for example, Wi-Fi access points, mobile towers, bluetooth and others.

GLONASS is a Russian Global Navigation Satellite System, which is similar to GPS and works in tandem with it, increasing the accuracy and speed of navigation.

The higher the standard, the faster the throughput, or more precisely the data exchange rate. With version 3.0 of the standard, the current was increased to 0.9A, eliminating the need for additional power for some devices.

Connecting a mobile device via USB as a data storage device. That is, when you enable this mode, your device can be used as a flash drive.

Additional features of the USB connector, for example, OTG, whether the connection is supported, peripheral devices and additional memory.

Does the device have a 3.5 mm audio jack?

NFC (Near field communication, near contactless communication) is a technology for contactless communication between devices over a short distance. Widely used for contactless payment, in the form of a travel card or pass, and is also used for reading and interacting with NFC tags and for exchanging data between devices.

Types of synchronization and connection technologies supported by the device.

Markup and programming languages ​​supported by the built-in (standard) browser. For mobile devices, you can install additional browser applications if the standard one does not suit you.

The formats that the mobile device supports out of the box are indicated. But if the device does not support the format you need, then you can try adding support for it. Sometimes support depends on the technical characteristics of the device (“hardware”) and nothing can be added here, but often the ability to process a particular audio format depends on the software part. You can install another audio player or codec set separately.

Video file formats that the device is capable of playing with standard firmware and a standard (built-in) set of programs. Not all formats are supported by default, but you can install a third-party video player and/or set of codecs.