1938 In March, the Nazis officially entered Austria, and then she also fled to London to stay away from her failed marriage and many Nazi "friends". By the way, it also brought the "military secrets" of Nazi wireless communication to the allies. These secrets are mainly based on the "command and guidance" system of radio secure communication, which is used to automatically control weapons and accurately attack targets. However, in order to prevent radio instructions from being stolen by the enemy, it is necessary to develop a series of security technologies for radio communication ―― she is well educated and secretly absorbs many valuable forward-looking concepts.
But in the end, she got the American patent in August of 1942. In the United States Patent Office, there is a patent for "secure communication system" with the patent number of 2292387. The patent was passed on Aug. 65438, 0942 1, and the application time was 65438. This technical patent applied on the website of the National Patent Office of the United States was originally used for military purposes.
Hedy lamarr initially studied this technology in order to help the US military create a military communication system that can deal with Nazi Germany's radio interference or prevent eavesdropping, so this technology was originally used in the military. After World War II, because it temporarily lost its value, the US military sealed up this technology, but its concept made many countries interested in it. Many countries have studied this technology in the 1960s, but little progress has been made.
Until 1985, a small company named "Qualcomm" was established in San Diego, USA (now a fortune 500 company). This company developed a new communication technology named "CDMA" by using the "spread spectrum technology" released by the US military, which directly led to the birth of 3G. The three global 3G standards, CDMA2000 in the United States, WCDMA in Europe and TD-SCDMA in China, are all developed on the basis of CDMA technology, which is the fundamental principle of 3G, and spread spectrum technology is the basic principle of CDMA.
The first generation of analog mobile phones (1995) can only make voice calls. From 1996 to 1997, the second-generation GSM, CDMA and other digital mobile phones (2G) have added the function of receiving data, such as receiving emails or web pages.
In May 2008, the International Telecommunication Union officially announced the third generation mobile communication standard, and TD-SCDMA submitted by China officially became an international standard. Together with WCDMA in Europe and CDMA2000 in the United States, it became one of the three most mainstream technologies in the 3G era.
As a new technology, CDMA and CDMA2000 are rapidly sweeping the world and have occupied 20% of the wireless market. By the end of 20 12, the number of CDMA2000 users worldwide had exceeded 256 million, and 156 operators in 70 countries had commercialized 3G CDMA services. Dozens of OEMs around the world, including Ankexin Communication Technology Co., Ltd. authorized by Qualcomm, have launched EVDO mobile intelligent terminals. In 2002, Qualcomm's chip sales reached a record high. From 65438 to 0994, Qualcomm has provided more than 7.5 billion chips to many global manufacturers, including China. 3G was born under this background.