PCM ( Pulse Code Modulation ) | T-Carrier Systems| Duplexing

Pulse-Code Modulation (PCM) PCM : The most popular form of TDM uses pulse-code modulation (PCM) (see Sec. 7-4), in which multiple channels of digital data are transmitted in serial form. Each channel is assigned a time slot in which to transmit one binary word of data. The data streams from the various channels are interleaved … Read more

Digital Codes | Hartley’s Law | ASCII | Asynchronous | Encoding Methods

Digital Codes Digital Codes: Data processed and stored by computers can be numerical (e.g., accounting records, spreadsheets, and stock quotations) or text (e.g., letters, memos, reports, and books). As previously discussed, the signals used to represent computerized data are digital, rather than analog. Even before the advent of computers, digital codes were used to represent … Read more

Multiplexer | Demultiplexer | FDM | TDM | PAM | Applications

Multiplexing Principles Multiplexer: Multiplexing is the process of simultaneously transmitting two or more individual signals over a single communication channel, cable, or wireless. In effect, it increases the number of communication channels so that more information can be transmitted. Often in communication, it is necessary or desirable to transmit more than one voice or data … Read more

Spread Spectrum | Wideband Modulation | Broadband Modem

Wideband Modulation Most modulation methods are designed to be spectrally efficient, i.e., to transmit as many bits per hertz as possible. The goal is to minimize the use of spectrum space and to transmit the highest speed possible in the given bandwidth. However, there is another class of modulation methods that do just the opposite. … Read more

Standing Waves | Matched Lines | Circuit Elements | Stripline | Microstrip

Standing Waves Standing Waves: When a signal is applied to a transmission line, it appears at the other end of the line sometime later because of the propagation delay. If a resistive load equal to the characteristic impedance of a line is connected at the end of the line, the signal is absorbed by the … Read more