RDI
Telephone networks have undergone a long evolution from its birth until today. These networks, the idea arose to allow communication between users spoken to were not on the same site, will be the basis of what is called information superhighway, that is, will be the basis of a network that will allow any type of information is transmitted through it. It’s going to explain each of the states that have passed through the telephone network and its features, thus a better understanding of where they are going to support the information superhighway. INTEGRATED DIGITAL NETWORK is the next step in the evolution of telephone networks, and arose from the need to provide better service to users, since the transmission through analog signals has numerous drawbacks. This communication between the central network will be done through digital lines, the local loop being the only element that kept the similar structure.
History Towards the end of the sixties and early seventies telecommunications is limited to communication by voice (via telephone) and written communication (by wire). Both services had different characteristics, so they have different networks for the transmission of information. But with the advancement of technology in the seventies came computers, and the problem of data communication between computers. This problem has been one of the causes of the evolution from analog transmissions to the switched telephone network to digital transmission of ISDN through the ROI (integrated digital network). Due to the wide spread of telephone networks, which provided service to nearly all the population in Western thought is in its use for data communication between computers. The transmission is the same as a normal phone call: ‘One of the computers had to dial the number of the destination computer. ‘At that point, a telephone communication line established between the two. ‘When the target computer received the ring due to “down” (up the call). ‘And then when computers could start to “talk” (transmit data). While the duration of ‘llamada , there was a direct connection between two computers (the line was devoted exclusively to such communication). For all intents and purposes, at that time, the behavior was the same as if you had a cable that directly join the two computers. However, there was a problem for communication between computers through traditional telephone networks. The problem was that the computers that handle data are digital, ie, to represent the ones and zeros, while the telephone network is designed to carry analog data, the information is represented by continuous functions. To solve this problem were designed devices whose mission was to “translate” the digital data to analog data (when the computer sends data to the telephone network, thus, could be transmitted through it) and analog to digital (computer where the data received from the telephone network). These devices are named after modem (modulator-demodulator). Another problem presented by the telephone network for communication between computers was that it was designed to transmit analog data in a limited frequency, which naturally included most of the sounds emitted by the human voice. This limitation supposed frequencies a significant transmission of digital data as the data to analog conversion should take place within that range of frequencies, which limits the speed of transmission, ie the number of data could be sent over the telephone network in a unit time. Analog signals also had other problems, which include the following: ‘The noise that is introduced into the links, whose removal was difficult. An example of noise in the telephone network is the interference or cross lines that occur at times. ‘The storage and processing of analog signals require complicated techniques and sophisticated equipment, and therefore expensive.These difficulties, among others, make that analogue technology is not the most suitable for an exchange of data, and resulted, apart from a network specializing in data communication between computers, the digitization of telephone networks, which still continues today to provide better service to users.
Ver video: 
The network minitrack was the first American network created for tracking satellites. Began operations in 1957. Tracheae was used for the flights of spacecraft Sputnik, Vanguard, Explorer, and other programs created during the early years of the conquest of space. Minitrack was the predecessor of network tracing