Information technology generally includes two categories: information processing technology and information transmission technology.
Information is an abstract concept. The specific forms of information are: language, text symbols, music, graphics, images and data. The physical signals representing sounds and images are converted into electrical signals through sensors, which become the objects of our processing, and people obtain information from these signals.
The task of communication is to transmit information, that is, to pass the processed information from one place to another. The most important requirement for information transmission is the reliability and validity of the transmission. The purpose of information processing is to transmit information more efficiently and reliably.
Transmission of information can be done by wire or wirelessly. Communication is the earliest application of radio technology, and its system composition and working process typically reflect the basic problems of radio technology. The development and modernization of communication technology also fully reflects the development and modernization of radio technology. This book will take the wireless communication system as the main research object, focusing on the basic principles and applications of electronic circuits such as high-frequency amplifiers and high-frequency power amplifiers, oscillators and frequency conversion in radio equipment.
The cell phone jammer can block the mobile phone signal, so that the mobile phone is in a state of no signal and no communication, and it can also block the signal of GPS, wifi and bluetooth.