Converters: There are many ways to convert digital codes to proportional analog voltages. However, the most popular methods are the R-2R, string, and weighted current source converters. These are available in integrated-circuit form and are also integrated into other larger systems on a chip (SoC). R-2R Converter The R-2R converter consists of four major sections, … Read more
Typical Receiver Circuits IF Amplifiers : This section focuses on RF and IF amplifiers, AGC and AFC circuits, and other special circuits found in receivers. RF Input Amplifiers The most critical part of a communication receiver is the front end, which usually consists of the RF amplifier, mixer, and related tuned circuits and is sometimes … Read more
VHF Aircraft Communication Circuit Receiver:- Most modern receivers are in IC form. Virtually all of the circuitry can be incorporated in a single chip. Some external discrete components are still needed but are minimal. These may include coils, bypass, and tuning capacitors, antennas, crystals, filters, and in the case of audio, a power amplifier, and … Read more
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
Modem Concepts and Methods FSK | PSK | DPSK : Binary signals are switched dc pulses, so how do such signals get transmitted over telephone lines, cable TV, coaxial cables, twisted-pair cables, or wireless links? Binary pulses can be transported over short cables even at very high data rates. The transformers, capacitors, and other ac … Read more
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
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
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
Protocols Protocols are rules and procedures used to ensure compatibility between the sender and receiver of serial digital data regardless of the hardware and software being used. They are used to identify the start and end of a message, identify the sender and the receiver, state the number of bytes to be transmitted, state a … Read more
Ethernet LANs One of the oldest and by far the most widely used of all LANs is Ethernet. Ethernet, which was developed by Xerox Corporation at Palo Alto Research Center in the 1970s, was based on the Aloha wide-area satellite network implemented at the University of Hawaii in the late 1960s. In 1980, Xerox joined … Read more