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Historical special investigation report

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The mobile phone was first invented by American IT giant Motorola. At present, the so-called second generation mobile phone (2G) is the most widely used in the world, which is mainly based on the GSM standard of modern mobile phones in Europe and CDMA in the United States, as well as the IDEN network standard of Motorola and PDC used in Japan. They are all in digital format. Besides voice communication, they can also send and receive short messages and wireless application protocols. GSM is the most popular in Chinese mainland and Taiwan Province province, and CDMA mobile phones are also very popular. At present, the whole industry is in the process of migrating to the third generation mobile phone (3G). In addition to typical telephone functions, some mobile phones also include PDA, game machine, MP3, camera, photography, recording, GPS, Internet access, etc., 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 and mobile phones, they are portable telephone terminals that can move in a large range.

At present, mobile phones are divided into smart phones and non-smart phones. Generally, smart phones have better performance than non-smart phones, but non-smart phones are more stable than smart phones. Most non-smart phones use the CPU of British ARM company as smart phones, but the frequency of smart phones is high (for example, the frequency of Motorola DROID X is as high as 1000 MHz, and the frequency of Nokia N97 is also 434 MHz), and the frequency of non-smart phones is low (for example, the frequency of Nokia 5000 is 50 MHz, and the frequency of Motorola ZN300 is 17 1).

Development history

1G

The first generation of mobile phones (1G) refers to analog mobile phones, which appeared in Hong Kong, the United States and other film and television works in the 1980s and 1990s. The first person to develop a mobile phone was Dr. Cooper from Motorola, USA. 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.

2G

The second generation mobile phone (2G) is also the most common mobile phone. Usually, these mobile phones use very mature standards such as PHS, 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.

third generation

3G, the abbreviation of English 3rdGeneration, refers to the third generation mobile communication technology. Compared with the first generation of analog mobile phones (1G) and the second generation of GSM, CDMA and other digital mobile phones (2G), the third generation of mobile phones generally refers to a new generation of mobile communication systems that combine 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. In order to provide this service, the wireless network must be able to support different data transmission speeds, that is, at least 2Mbps (megabits per second), 384kbps (kilobits per second) and 144kbps in indoor, outdoor and driving environments respectively. Compared with the first generation of analog mobile phones (1G) and the second generation of GSM, TDMA and other digital mobile phones (2G), 3G communication has many names, which are defined by ITU as "IMT-2000" (International Mobile Phone 2000) and called "UMTS" by European telecom giants. At present, 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. Now, "3G communication" is about to become the mantra in people's mouths. The so-called 3G, in fact, is the third generation, 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. It can handle various media forms, such as images, music and video streams, and provide various information services, including web browsing, teleconference and e-commerce. Compared with the first generation analog mobile phones (1G) and the second generation digital mobile phones (2G) such as GSM and TDMA, 3G communication has many names, which are defined by ITU as "IMT-2000" (International Mobile Phone 2000) and called "UMTS" universal mobile telecommunications system by European telecom giants. 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 organizations and operators.

Current mobile phone

At present, 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 the 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 handheld computers with mobile phone functions.

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