Network fundamentals week 3 lessons Transmission Basics Networking is all about signals, the transmission of, receiving of, and manipulation of data signals. Transmission has two meanings: the process of issuing data signals on a medium and the progress of data signals over a medium. On a data network information is transmitted via one of two methods, Analog and Digital. Analog and Digital Signaling An analog system sends information by encoding it as a continuous change in voltage or current. The receiving end then decodes these changes back into usable information. For example, an analog clock represents the sun circling the sky. An analog device converts a pattern, such as light or sound patterns, into electrical signals with similar patterns. The definition of an analog signal can also reveal its shortcomings. Analog signals, because they rely on minute variations in voltage or current, are very susceptible to interference from outside sources. Even a small change in the analog signal from an outside source, such as electromagnetic interference, can cause dramatic changes in the signal and how the signal is interpreted. Digital is defined as, "of, relating to, or using calculation by numerical methods or by discrete units." A better way to describe digital is to contrast it against an analog signal. In a digital signal, numerical values are finite. For example, if we were counting from zero to one, only the two values are represented. In an analog system, everything between zero and one are represented as well. A digital signal is like binary in that it is either on or off - one or zero. Only two states are represented. Using this binary system to transmit data has a tremendous advantage over transmitting the same signal via analog. The signal is not as susceptible to interference from outside sources and can be transmitted over very long distances. The receiving end of the transmission only needs to recognize if there is any signal or no signal transmitted over a given time period. The four fundamental properties of analog signals Both analog and digital signals are generated by electrical current, the pressure of which is measured in volts. (The strength of an electrical signal is directly proportional to its voltage.) • An analog signal, like other waveforms, is characterized by four fundamental properties: amplitude, frequency, wavelength, and phase. Amplitude is a measure of strength of a wave at any given point in time. Frequency is the number of times a signal s amplitude changes over a period and is expressed in hertz (Hz). Wavelength is the distances between corresponding points on a wave s cycle. Phase refers to progress of a wave over time in relationship to a fixed point, kind of like a rating of speed.
- Spring '16
- Kyle Jones
- Networking, Twisted pair, Coaxial cable