Americans
One day in April 1973, a man stood on the street in New York, took out a wireless phone about two bricks in size, and made a call. Passers-by stopped and looked sideways. This man is Martin Cooper, the inventor of the mobile phone. At that time, Cooper was an engineering technician at the famous American Motorola Company.
The world's first mobile phone call was made to a rival of his working at Bell Labs, who was also developing a mobile phone at the time, but had not yet succeeded. Cooper later recalled: "I called him and said, 'Joe, I'm talking to you on a portable cell phone right now.' I heard 'gnashing of teeth' on the other end of the phone - even though he had kept up quite a bit. Courtesy. ”
In April this year, the mobile phone will have been born for 30 years. This product of competition among scientific and technological personnel has now blossomed everywhere, bringing great convenience to our modern life.
Martin Cooper is 74 years old this year. After working at Motorola for 29 years, he founded his own communications technology research company in Silicon Valley. Currently, he is the company's chairman and chief executive officer. Martin Cooper's idea at the time was to let the media know that wireless communications - especially small mobile communication phones - were very valuable. In addition, he also hopes to arouse the interest of the US Federal Communications Commission and support Motorola in its competition with AT&T (AT&T is also a major communications company in the United States).
In fact, if we go back further, we will find that the concept of mobile phones appeared as early as the 1940s. At that time, Bell Labs, the largest communications company in the United States, began trial production. In 1946, Bell Labs built the first so-called mobile phone. However, due to its large size, researchers could only put it on a shelf in the laboratory, and people gradually forgot about it.
It was not until the late 1960s that AT&T and Motorola became interested in this technology. At that time, AT & T rented out a large mobile wireless phone that customers could install on large trucks. AT&T's idea is to develop a mobile phone with a power of 10 watts in the future and use the radio equipment on the truck to communicate. Cooper believed that the phone was too big and heavy to be moved and carried around. Therefore, Motorola applied to the Federal Communications Commission of the United States, requesting that the power of mobile communication equipment should only be one watt, and the maximum should not exceed three watts. In fact, the radio power of most mobile phones today is only 500 milliwatts at most.
From the time the mobile phone was patented in 1973, it was not until 1985 that the first truly mobile phone in the modern sense was born. It places the power supply and antenna in a box and weighs 3 kilograms. It is very heavy and inconvenient. The user has to carry it like a backpack when walking, so it is called a "shoulder phone".
The mobile phone, which is similar in shape to today, was born in 1987. It is much lighter and easier to carry than a "shoulder phone". Still, it weighs about 750 grams, which is like a big brick compared to today's phones that weigh just 60 grams.
Since then, mobile phones have developed more and more rapidly. In 1991, the weight of mobile phones was about 250 grams; in the autumn of 1996, a mobile phone with a volume of 100 cubic centimeters and a weight of 100 grams appeared. Since then, it has been further miniaturized and lightened, and by 1999 it weighed less than 60 grams. In other words, a mobile phone is not much heavier than an egg.
In addition to getting smaller and smaller in quality and size, modern mobile phones have become more and more like a multi-functional Swiss Army knife. In addition to the most basic call functions, new mobile phones can also be used to send and receive emails and short messages, surf the Internet, play games, take photos, and even watch movies! This was something the original inventor of the mobile phone never expected.
In terms of communication technology, modern mobile phones have also made significant progress. When Cooper made the world's first mobile phone call, he could use any electromagnetic spectrum.
In fact, the first generation of analog mobile phones relied on different frequencies to distinguish different mobile phones for different users. The second generation of mobile phones, the GSM system, relies on extremely small time differences to distinguish users. Today, frequency resources are obviously insufficient, and mobile phone users are growing exponentially. As a result, newer CDMA technology, which relies on different encodings to distinguish different machines, came into being. Mobile phones using this technology not only have better call quality and confidentiality, but can also reduce radiation and can be called "green mobile phones."