Where can I find QQ historical avatar on my mobile phone?

(mobile phone)

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This entry is reviewed by the project of sorting out and applying scientific entries of "Popular Science China".

Mobile phone, or wireless phone, usually called mobile phone, was originally just a communication tool. In the early days, it was also called [1] as a mobile phone terminal that can be widely used. It was originally developed from the battlefield mobile phone manufactured by Bell Laboratories in 1940.

1958 [2], Soviet engineer Leonid Kupriyan Norwich invented лк- 1 mobile phone, 1973 [3], American Motorola engineer martin cooper invented the world's first commercial mobile phone. So far, it has developed into the 4G era.

Why does the mobile phone turn off when it is cold?

Since it snowed several times, the temperature in the north has been dropping continuously, even as low as MINUS 10 degrees. As the temperature drops, in addition to making people stiff, many mobile phone users find that their mobile phones seem to be "cold" and automatically turn off at every turn. What the hell is going on here?

Why did it turn off when it was cold? more

Smart phones use lithium batteries, the normal working temperature is 0~40℃, and the limit is -20~70℃. When the battery temperature is too low, its low temperature protection will start, and the battery has electricity but cannot be released. The temperature difference between indoor and outdoor is too large, and the water vapor condenses on the mobile phone and enters the mobile phone motherboard. So the phone will suddenly turn off or crash.

What is low temperature protection? more

Most electronic products on the market use lithium-ion polymer batteries. Most lithium batteries are equipped with low temperature protection. The larger the battery capacity, the higher the protection level. If the temperature is too low, the lithium metal in the battery will precipitate and no chemical reaction will occur.

Content arrangement Shen Yiya

Chinese name

mobile phone

Foreign name

mobile phone

Date of invention

1973

famous brand

Apple, Samsung, Huawei, Lenovo, HTC, etc

Domestic brand

ZTE, Huawei, Lenovo, Coolpad, Xiaomi, etc

inventor

marty cooper

operating system

Android, IOS, Saipan, WP, Firefox, etc.

classify

Smart phones, non-smart phones, skateboarding phones

Network standard

2G 3G 4G

catalogue

1 classification

2 development history

Development history

Development details

3 appearance

Clam shell type

Straight plate type

Sliding cover type

Watch style

rotary type

Side slip type

4 operation mode

key type

touch screen

5 operating system

robot

ios

Intelligent mobile terminal operating system

Windows mobile phone

Firefox operating system

MeeGo

Cash On Shipment

6 mobile phone market

Classification by operating system

According to mobile phone manufacturers,

Seven uses

business affairs

picture

Learning application

the aged

children

Buying and selling securities and stocks

music

TV

match

High definition movie

ultrathin

Tablet computer

Smart card swiping

8 domestic operators

China Mobile

China Telecom

China Unicom

9 maintenance

Mobile phone for rescuing water inflow

Mobile phones focus on maintenance.

Daily maintenance

battery

Radiation prevention

phone case

Purchase suggestion

10 Mobile Banking

classify

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Mobile phones are divided into smart phones [4] and non-smart phones (function phones). Generally, the performance of smart phones is better than that of non-smart phones, but the performance of non-smart phones is more stable than that of smart phones. Most non-smart phones and smart phones use the CPU of British ARM company. Smartphones have higher main frequency, faster running speed, faster processing tasks and more convenient daily life (such as Nokia n8 1 main frequency of 369 MHz); Instead of smart phones, the frequency is relatively low and the running speed is slow (for example, the main frequency of Nokia 5000 is 50 MHz).

Smart phones, like personal computers, have independent operating systems, most of which are large-screen machines, touch capacitive screens, and some are resistive screens, which are powerful and practical. Users can install programs provided by third-party service providers, including games, which can continuously expand the functions of mobile phones and realize wireless network access through mobile communication networks. Generally speaking, it is a simple formula of "1+1=" PDA+mobile phone = smart phone ". Broadly speaking, smart phone not only has the function of talking on mobile phone, but also has most functions of PDA, especially personal information management based on wireless data communication, browser and email functions. Smart phones provide users with enough screen size and bandwidth, which is not only convenient to carry around, but also provides a broad stage for software operation and content services. Many value-added services can be developed in this respect, such as: stock, news, weather, transportation, goods, application download, music and picture download, etc. [5].

phylogeny

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If we go back, we will find that the concept of mobile phone appeared as early as 1940s. At that time, Bell Laboratories, the largest communication company in the United States, began trial production. 1940, Bell Laboratories manufactured the first so-called mobile phone. But because of its large size, researchers can only put it on the shelf in the laboratory, and people will gradually forget it.

1973 in April, marty cooper, an engineer and technician of the famous American Motorola Company, invented the world's first civil mobile phone. When Cooper made the world's first mobile phone, he could use any electromagnetic frequency band. The first generation of analog mobile phones is actually to distinguish different mobile phones of different users by different frequencies. The second generation mobile phone -GSM system distinguishes users with a very small time difference. Today, the frequency resources are obviously insufficient, and the number of mobile phone users is also growing rapidly in geometric series. As a result, the updated CDMA technology, using different codes to distinguish different computers, came into being. The mobile phone using this technology not only has better call quality and confidentiality, but also can reduce radiation, which is called "green mobile phone".

Development history

183 1 year [2] Faraday discovered the phenomenon of electromagnetic induction in England, and Maxwell further expounded the research results of Faraday and others with mathematical formulas, and extended the theory of electromagnetic induction to space. More than 60 years later, Hertz confirmed the existence of electromagnetic waves in experiments. The discovery of electromagnetic waves has become the turning point from "wired communication" to "radio communication" and the origin of the whole mobile communication. As a scientist said, "Mobile phones were born on the shoulders of telegrams and telephones. Without the efforts of predecessors, wireless communication is impossible [3].

124 May 844 [6]. Morse's telegram sent the first telegram from Washington to Baltimore in human history. "What a miracle God has created!" "

1On June 2, 875, Bell accidentally spilled sulfuric acid on his leg while doing the experiment. He was in pain and shouted to his colleagues in the other room, "Come and help me!" " And this sentence passed through the telephone in the experiment to the living ear of another room, which became the first sentence transmitted by human beings by telephone [2-3].

1902 [2] An American named Nathan Stubblefield made the first wireless telephone equipment in his country house in Murray, Kentucky. This kind of wireless mobile communication telephone is the earliest exploration and research on "mobile phone" technology [8].

1940, Bell Laboratories made mobile phones for war.

1946, the first telephone call in the world was made in a moving car in St. Louis [9].

1957, Leonid, an outstanding engineer in the Soviet Union. Kupriyan Norwich invented лк- 1 mobile phone. In 1958, he further improved his mobile phone. The weight of the equipment is reduced from 3 kg to 500 g (including the battery weight), and the shape is simplified to the size of two cigarette cases, so that you can make a phone call anywhere in the city and connect any fixed telephone. By the mid-1960s, the mobile phones in Norich, Kupriyan had been able to work effectively within 200 kilometers [2].

1958, the Soviet union began to develop the world's first fully automatic mobile phone communication system "Altai" (алтай) [1 1]. 1959, the "Altai" system with excellent performance won the gold medal of the Brussels World Expo [10].

1973, a man stood on the street in new york, pulled out a wireless phone about the size of two bricks and started talking.

Marty cooper (marty cooper)

This man is marty cooper, the inventor of mobile phone. At that time, he was an engineer at Motorola. This is the first mobile phone in the world.

1975, the Federal Communications Commission (FCC) of the United States determined the spectrum of land mobile phone communication and large-capacity cellular mobile phone. It is ready for the commercialization of mobile phones [3].

1979, Japan opened the world's first cellular mobile phone network [3].

1982, Europe established GSM (Mobile Communication Task Force) [3].

1985, the first commercial mobile phone was born. It puts the power supply and antenna in an example and weighs 3 kilograms.

The modern mobile phone was born in 1987. Its weight is still about 750 grams, which is like a big brick compared with today's mobile phone with only 60 grams.

Since then, the "slimming" of mobile phones has become more and more rapid. 199 1 year [3], and the weight of the mobile phone is about 250g. 1autumn of 996 [3] A mobile phone with a volume of 100 cubic centimeter and a weight of 100 gram appeared. Since then, it has been further miniaturized and lightweight, and 1999 has been lighter than 60 grams [3].

Development details

At present, the so-called third generation mobile phone (3G) is the most widely used in the world, which is mainly based on the GSM system in Europe and the CDMA system in the United States. They are all digital systems, which can not only carry out voice communication, but also send and receive short messages and wireless application protocols. In Chinese mainland and Taiwan Province Province, GSM is the most popular, CDMA mobile phones are also very popular, and the whole industry is migrating to the fourth generation mobile phones (4G). In addition to typical telephone functions, some mobile phones also include PDA, game machine, MP3, camera, photography, recording, GPS, Internet access and other functions, and there is a trend to develop mobile phone functions to PDA. The microphone and earphone of the telephone and the corresponding microphone and receiver are all installed on one handle. Formerly known as mobile phones, handheld devices, mobile phones and faxes, they are portable telephone terminals that can move in a large range [13].

According to industry analysts, although the basic protection functions of mobile phone security products are relatively complete, there are still shortcomings in anti-harassment, privacy protection and data protection, and there is still a large market space in the future. QQ mobile phone housekeeper, security housekeeper, NetQin and other security vendors have announced their entry into the field of cloud security. 20 13 will be a crucial year for the accelerated landing of mobile cloud security, and major security vendors will continue to increase their investment in mobile cloud security solutions.

1G

The first generation mobile phone (1G) refers to analog mobile phones, which appeared in China, Hongkong, the United States and other film and television works in 1980s and 1990s. The first person who invented the mobile phone was Dr. Cooper from America. Due to the limitation of battery capacity and the development of analog modulation technology, such as huge antenna and integrated circuit, this mobile phone has a square appearance and can only be moved, but not portable. Many people call this kind of mobile phone "brick" or "Black King Kong".

There are many formats of this kind of mobile phone, such as NMT, AMPS, TACS, etc., but frequency division multiplexing can only be used for voice communication, with unstable reception effect, insufficient confidentiality and insufficient wireless bandwidth. This kind of mobile phone is similar to a simple radio duplex station. The call is locked on a certain frequency, and you can use FM radio to eavesdrop on the call. [ 14]

2G

The second generation mobile phone (2G) is also the most common mobile phone. Usually, these mobile phones use very mature standards such as GSM or CDMA, with stable call quality and appropriate standby time. In the second generation, in order to meet the needs of data communication, some intermediate standards are also supported on mobile phones, such as GPRS supporting MMS service, WAP service for Internet service, and various Java programs.

2.5G

Some mobile phone manufacturers call some of their mobile phones 2.5G mobile phones, which are characterized by GPRS function [15].

2.75 grams

Some mobile phone manufacturers also refer to some of their own mobile phones as 2.75G mobile phones, which are characterized by faster EDGE function than GPRS [3].

third generation

3G[ 16] is the abbreviation of the third generation in English, which refers to the third generation mobile communication technology. Compared with the first generation analog mobile phone (1G) and the second generation digital mobile phone (2G), the third generation mobile phone generally refers to a new generation mobile communication system which combines wireless communication with multimedia communication such as the Internet. It can handle images, music, video streams and other media forms, and provide a variety of information services including web browsing, teleconference, e-commerce and so on. That is to say, in indoor, outdoor and driving environments, it can support at least 2Mbps (megabits per second), 384kbps (kilobits per second) and 144kbps respectively.

ITU defines 3G mobile phone as IMT-2000 (International Mobile Phone 2000) standard, and European telecom giants call it "UMTS" universal mobile telecommunication system.

There are three international standards for 3G mobile phones: WCDMA in Europe, CDMA2000 in the United States and TD-SCDMA proposed by scientists in China.

"3G communication" is about to become people's mantra. The so-called 3G, in fact, its full name is 3G, which means the third generation digital communication in Chinese. 1995, the first generation of digital mobile phones, can only make voice calls; The second generation digital mobile phones from 1996 to 1997 have added the function of receiving data, such as accepting emails or web pages; The main difference between the third generation and the first two generations is that the speed of transmitting sound and data has increased. Compared with the first generation of analog mobile phones (1G) and the second generation of 2G digital mobile phones, 3G communication has many names. ITU defines it as "IMT-2000" (International Mobile Phone 2000) standard, and European telecom giants call it "UMTS" universal mobile telecommunications system. According to the standard, when the mobile terminal moves at vehicle speed, its data transmission rate is 144kbps, the outdoor stationary or walking speed is 384kbps, and the indoor speed is 2Mbps. However, these requirements do not mean that the available rate of users can reach 2Mbps, because the indoor rate will also depend on the detailed frequency planning in the building and the close cooperation between institutions and operators [17].

3.5 g /3.75 g

3.5G adopts HSDPA, HSDPA+, HSDPA 2+ and HSUDA. Users can enjoy a download rate of 7.2M to 42m.. While providing high-speed data services, security has also been improved, and 3.5G mobile phones focus on security and data communication. On the one hand, it strengthens the protection of personal privacy, on the other hand, it strengthens the research and development of data services and introduces more multimedia functions. The mobile phone has stronger computing power, which is no longer just a personal call and text information terminal, but more functional choices. Mobile office and strong communication demand will accelerate the integration of mobile phones and personal computers, and mobile phones will gradually have the functions of personal computers, which has been fully reflected in the mobile phone market in China [3] [15].

the 4th generation mobile communication technology

4G is the abbreviation of the fourth generation mobile communication and its technology, which can transmit high-quality video images and technical products, and the image transmission quality is equivalent to that of HDTV.

Mobile phones that have been developing.

The most widely used mobile phones in the world are GSM and CDMA. In Chinese mainland and Taiwan Province Province, GSM is the most popular, and CDMA and PHS mobile phones are also very popular. These are the so-called second generation mobile phones (2G). They are all in digital format. Besides voice communication, they can also send and receive short messages (SMS), multimedia messages (technology) and wireless application protocol (WAP).

Generally, the appearance of a mobile phone should include at least one LCD screen and a set of buttons (some touch-screen phones reduce buttons). In addition to typical telephone functions, some mobile phones also include PDA, game machine, MP3, camera, recording, photographing, positioning and other functions, and there is a tendency to develop into Pocket PC with mobile phone functions [9].

external

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As the name implies, mobile phone type refers to the external type of mobile phone. Commonly used classification is to divide mobile phones into straight type, folding type (single screen, double screen), sliding type, rotary type, side sliding type and so on.

Clam shell type

Only by opening the cover can you see the main display screen or buttons, and there is only one screen, then this kind of mobile phone is called a single-screen flip phone. There is also a dual-screen flip phone in the market, that is, there is an auxiliary display screen on the flip, which is usually relatively small and can generally display functions such as time, signal, battery and incoming number.

Straight plate type

Straight mobile phone means that the screen and buttons of the mobile phone are on the same plane, and the mobile phone has no flip cover. That is what we often call a straight mobile phone. The main feature of upright mobile phone is that it can directly see the content displayed on the screen.

Sliding cover type

Sliding the mobile phone mainly means that the mobile phone can only see the whole body when it is pulled. Some models can only see the keys by sliding the lower cover; Others can only see the keyboard by pulling up the screen part. To some extent, the slide phone is an extension and innovation of the flip phone.

Watch style

Wristwatch-type mobile phones were mostly simple and small functions in the early days, but with the development of smart phones, the functions of wrist-type mobile phones are more complete, such as Samsung's Galaxy Gear V700. The earliest domestic mobile phone watch was Ami.

rotary type

Similar to the slide type, the most important thing is that you can see the keyboard after180 rotation.

Side slip type

It is a variant of the slide type, which is operated by pushing the screen to the left or right to expose the keyboard. For smart phones with large screen touch operation, sideslip greatly speeds up typing, improves and optimizes the experience of playing games, and makes such smart phones more popular. Such as Nokia N97 and Motorola Milestone.

Operation mode

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key type

Push-button mobile phones used to be the mainstream of the mobile phone market. Since the birth of the mobile phone, it has various types of buttons. At the earliest time, the mobile phone was the only medium to interact with users, and the importance of the keyboard was self-evident. All operations such as making phone calls and sending text messages could be completed through the keyboard.

touch screen

Touch screen mobile phone is the trend of modern mobile phone market. Touch screen mobile phones can be divided into resistive screen and capacitive screen mobile phones, which refers to a kind of mobile phones that use touch screen technology to apply this technology to the screen of mobile phones. There is no clear boundary between touch-screen mobile phones and other mobile phones. The biggest feature is its large screen, which can bring visual enjoyment to users, and embodies the characteristics of large screen in words and images. However, due to the large screen and volume, carrying a touch-screen mobile phone takes up a lot of space. At the same time, the touch-screen mobile phone can be controlled by fingers, which perfectly replaces the keyboard.

operating system

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robot

Android is an open source mobile phone operating system based on Linux platform released by Google on June 5438+065438+1October 5, 2007. The platform consists of operating system, middleware, user interface and application software [18].

The word Android originally meant "robot". At the same time, the system architecture of Android, like its operating system, adopts hierarchical architecture. From the architecture diagram, Android is divided into four layers, namely, application layer, application framework layer, system running layer and Linux kernel layer.

Before the official release of Android, there were two beta versions at first, and they were named after famous robots.

Astro boy and clockwork robot (AndroidBeta 1.0).

Later, due to copyright issues, Google changed the naming rules to use dessert as their system version code. Dessert naming began when Android 1.5 was released.

As the representative of each edition, the size of desserts is getting bigger and bigger, and then the numerical order of 26 letters is: cupcakes (Android 1.5), doughnuts (Android 1.6), muffins (Android 2.0/2. 1), frozen yogurt (Android 2.2) and frozen yogurt.

Representative support manufacturers: Samsung, Xiaomi, Huawei, Meizu, ZTE, Motorola, HTC, LG, Sony.

ios

IOS is a closed-source operating system developed by Apple for iPhone, iPod touch and iPad. Just like its Mac OS X operating system, it is also based on Darwin. Originally, this system was called iPhone OS, until it was announced to be renamed as iOS at the WWDC conference on June 7, 20 10. The architecture of iOS is divided into four layers: core OS layer, core service layer, media layer and Cocoa Touch layer. Has developed to iOS 8. 1.3.

Support vendor: Apple.

Intelligent mobile terminal operating system

Symbian operating system is an operating system designed by Symbian company for mobile phones, including joint database, user interface architecture and reference implementation of public tools. Its predecessor was the psychic EPOC. In February 2008, it was acquired by Nokia. Symbian used to be the most used operating system in the mobile market, occupying most of the market share. However, with Google's Android system and Apple's iphone rapidly occupying the mobile phone system market, Symbian has basically lost its dominant position in the mobile phone system. There are many branches of Symbian system, including early Symbian S80, Symbian S90 and Symbian UIQ, as well as the third generation of Symbian S60, the fifth generation of Symbian S60, Symbian^3, Symbian Anna and Symbian Belle. Saipan system officially ended on 20 13 65438124 October, bidding farewell to the historical stage. The last mobile phone equipped with Saipan system is Nokia 808 pureview.

Main support vendors: Nokia, Sony.

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