Communication Test Equipment This section gives a broad overview of the many different types of test instruments available for use with communication equipment. It is assumed that you already know basic test and measurement techniques used with conventional low-frequency test equipment, such as multimeters, signal generators, and oscilloscopes. In your communication work, you will continue … Read more
Infrared Wireless Perhaps the most widespread wireless system uses infrared light for short-distance data communication. The most ubiquitous example is the wireless remote control on virtually all TV sets, DVD players, and most audio CD stereo systems. This standard feature on most consumer electronic products is so common that it is taken for granted. Infrared … Read more
Wireless LAN Wireless LANs are more commonly referred to by their trade name Wi-Fi. The terms Wi-Fi, WLAN, and 802.11 are used interchangeably in this text. Local-area networks (LANs) within a company, government agency, hospital or other organization typically use CAT5 or CAT6 unshielded twisted pair as the transport medium. However, more and more, wireless … Read more
Long Term Evolution ( LTE ) and 4G Cellular Systems Long Term Evolution (LTE) is the wireless cellular technology that is being adopted around the world as the primary cell phone communications service. Multiple 2G and 3G cellular radio methods are heading toward phase-out as carriers build their new LTE networks. It will be years … Read more
Cellular Telephone Systems A cellular radio system provides standard telephone service by two-way radio at remote locations. Cellular radios or telephones were originally installed in cars or trucks, but today most are handheld models. Cellular telephones permit users to link up with the standard telephone system, which permits calls to any part of the world. … Read more
Wavelength-Division Multiplexing WDM : Data is most easily multiplexed on fiber-optic cable by using time-division multiplexing (TDM), as in the T1 system or in the SONET system described later in this chapter. However, developments in optical components make it possible to use frequency- division multiplexing (FDM) on fiber-optic cable (called wavelength-division multiplexing, or WDM), which … Read more
Optical Transmitters and Receivers In an optical communication system, transmission begins with the transmitter, which consists of a carrier generator and a modulator. The carrier is a light beam that is usually modulated by turning it on and off with digital pulses. The basic transmitter is essentially a light source. The receiver is a light … Read more
Optical Principles Optical : Optics is a major field of study in itself and far beyond the scope of this book. Most courses in physics introduce the basic principles of light and optics. We review briefly those principles that relate directly to optical communication systems and components. Light Light, radio waves, and microwaves are all … Read more
Facsimile Facsimile, or fax, is an electronic system for transmitting graphic information by wire or radio. Facsimile is used to send printed material by scanning it and converting it to electronic signals that modulate a carrier to be transmitted over telephone lines. Since modulation is involved, fax transmission can also take place by radio. With … Read more
Telephones The original telephones system was designed for full-duplex analog communication of voice signals. Today, the telephone system is still primarily used for voice, but it employs mostly digital techniques, not only in signal transmission but also in control operations. The telephone system permits any telephone to connect with any other telephone in the world. … Read more