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Baud In telecommunication and electronics, baud (/ˈbɔːd/; symbol: Bd) is a common measure of the speed of communication over a data channel. Technically speaking, it is the unit for symbol rate or modulation rate in symbols per second or pulses per second. It is the number of distinct symbol changes (signaling events) made to the transmission medium per second in a digitally modulated signal or a line code. Baud Baud was the prevalent measure for data transmission speed until replaced by the term bps (bits per second), to which it closely approximates. If there are only two symbols in the alphabet (typically 0 and 1), then baud and bits per second (bps) are equivalent. Baud Baud is related to gross bit rate or symbol rate expressed as bits per second [...More...]  "Baud" on: Wikipedia Yahoo 

Analog Signal An analog signal is any continuous signal for which the time varying feature (variable) of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. For example, in an analog audio signal, the instantaneous voltage of the signal varies continuously with the pressure of the sound waves. It differs from a digital signal, in which the continuous quantity is a representation of a sequence of discrete values which can only take on one of a finite number of values.[1][2] The term analog signal usually refers to electrical signals; however, mechanical, pneumatic, hydraulic, human speech, and other systems may also convey or be considered analog signals. An analog signal uses some property of the medium to convey the signal's information. For example, an aneroid barometer uses rotary position as the signal to convey pressure information [...More...]  "Analog Signal" on: Wikipedia Yahoo 

Eye Diagram In telecommunication, an eye pattern, also known as an eye diagram, is an oscilloscope display in which a digital signal from a receiver is repetitively sampled and applied to the vertical input, while the data rate is used to trigger the horizontal sweep. It is so called because, for several types of coding, the pattern looks like a series of eyes between a pair of rails. It is a tool for the evaluation of the combined effects of channel noise and intersymbol interference on the performance of a baseband pulsetransmission system. It is the synchronised superposition of all possible realisations of the signal of interest viewed within a particular signaling interval. Several system performance measures can be derived by analyzing the display. If the signals are too long, too short, poorly synchronized with the system clock, too high, too low, too noisy, or too slow to change, or have too much undershoot or overshoot, this can be observed from the eye diagram [...More...]  "Eye Diagram" on: Wikipedia Yahoo 

Nyquist Rate In signal processing, the Nyquist rate, named after Harry Nyquist, is twice the bandwidth of a bandlimited function or a bandlimited channel [...More...]  "Nyquist Rate" on: Wikipedia Yahoo 

Constellation Diagram A constellation diagram is a representation of a signal modulated by a digital modulation scheme such as quadrature amplitude modulation or phaseshift keying.[1] It displays the signal as a twodimensional xyplane scatter diagram in the complex plane at symbol sampling instants. In a more abstract sense, it represents the possible symbols that may be selected by a given modulation scheme as points in the complex plane. Measured constellation diagrams can be used to recognize the type of interference and distortion in a signal.A constellation diagram for Gray encoded 8PSK.By representing a transmitted symbol as a complex number and modulating a cosine and sine carrier signal with the real and imaginary parts (respectively), the symbol can be sent with two carriers on the same frequency. They are often referred to as quadrature carriers. A coherent detector is able to independently demodulate these carriers [...More...]  "Constellation Diagram" on: Wikipedia Yahoo 

Signaltonoise Ratio Signaltonoise ratio Signaltonoise ratio (abbreviated SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio of signal power to the noise power, often expressed in decibels. A ratio higher than 1:1 (greater than 0 dB) indicates more signal than noise. While SNR is commonly quoted for electrical signals, it can be applied to any form of signal for example isotope levels in an ice core or biochemical signaling between cells or financial trading signals. The signaltonoise ratio, the bandwidth, and the channel capacity of a communication channel are connected by the Shannon–Hartley theorem. Signaltonoise ratio Signaltonoise ratio is sometimes used metaphorically to refer to the ratio of useful information to false or irrelevant data in a conversation or exchange [...More...]  "Signaltonoise Ratio" on: Wikipedia Yahoo 

Basic Rate Interface Basic Rate Interface Basic Rate Interface (BRI, 2B+D, 2B1D) or Basic Rate Access is an Integrated Services Digital Network Integrated Services Digital Network (ISDN) configuration intended primarily for use in subscriber lines similar to those that have long been used for voicegrade telephone service. As such, an ISDN BRI connection can use the existing telephone infrastructure at a business. The BRI configuration provides 2 data (bearer) channels (B channels) at 64 kbit/s each and 1 control (delta) channel (D channel) at 16 kbit/s. The B channels are used for voice or user data, and the D channel is used for any combination of data, control/signaling, and X.25 X.25 packet networking. The 2 B channels can be aggregated by channel bonding providing a total data rate of 128 kbit/s [...More...]  "Basic Rate Interface" on: Wikipedia Yahoo 

64QAM Quadrature amplitude modulation Quadrature amplitude modulation (QAM) is both an analog and a digital modulation scheme. It conveys two analog message signals, or two digital bit streams, by changing (modulating) the amplitudes of two carrier waves, using the amplitudeshift keying (ASK) digital modulation scheme or amplitude modulation (AM) analog modulation scheme. The two carrier waves of the same frequency, usually sinusoids, are out of phase with each other by 90° and are thus called quadrature carriers or quadrature components — hence the name of the scheme. The modulated waves are summed, and the final waveform is a combination of both phaseshift keying (PSK) and amplitudeshift keying (ASK), or, in the analog case, of phase modulation (PM) and amplitude modulation. In the digital QAM case, a finite number of at least two phases and at least two amplitudes are used [...More...]  "64QAM" on: Wikipedia Yahoo 

Ralph Hartley Ralph Vinton Lyon Hartley (November 30, 1888 – May 1, 1970) was an electronics researcher. He invented the Hartley oscillator Hartley oscillator and the Hartley transform, and contributed to the foundations of information theory.Contents1 Biography 2 Awards 3 Publications 4 See also 5 Notes 6 ReferencesBiography[edit] Hartley was born in Sprucemont, Nevada and attended the University of Utah, receiving an A.B. degree in 1909. He became a Rhodes Scholar at St Johns, Oxford University, in 1910 and received a B.A. degree in 1912 and a B.Sc. degree in 1913. He married Florence Vail of Brooklyn on March 21, 1916.[1] The Hartleys had no children. He returned to the United States United States and was employed at the Research Laboratory of the Western Electric Western Electric Company [...More...]  "Ralph Hartley" on: Wikipedia Yahoo 

Logarithm In mathematics, the logarithm is the inverse operation to exponentiation, just as division is the inverse of multiplication. That means the logarithm of a number is the exponent to which another fixed number, the base, must be raised to produce that number. In the most simple case the logarithm counts repeated multiplication of the same factor; e.g., since 1000 = 10 × 10 × 10 = 103, the "logarithm to base 10" of 1000 is 3. More generally, exponentiation allows any positive real number to be raised to any real power, always producing a positive result, so the logarithm can be calculated for any two positive real numbers b and x where b is not equal to 1. The logarithm of x to base b, denoted logb (x) (or logb x when no confusion is possible), is the unique real number y such that by = x. For example, log2 64 = 6, as 64 = 26. The logarithm to base 10 (that is b = 10) is called the common logarithm and has many applications in science and engineering [...More...]  "Logarithm" on: Wikipedia Yahoo 

Metric Prefix A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or fraction of the unit. While all metric prefixes in common use today are decadic, historically there have been a number of binary metric prefixes as well.[1] Each prefix has a unique symbol that is prepended to the unit symbol. The prefix kilo, for example, may be added to gram to indicate multiplication by one thousand: one kilogram is equal to one thousand grams. The prefix milli, likewise, may be added to metre to indicate division by one thousand; one millimetre is equal to one thousandth of a metre. Decimal Decimal multiplicative prefixes have been a feature of all forms of the metric system, with six dating back to the system's introduction in the 1790s. Metric prefixes have even been prepended to nonmetric units [...More...]  "Metric Prefix" on: Wikipedia Yahoo 

Telecommunication Telecommunication Telecommunication is the transmission of signs, signals, messages, words, writings, images and sounds or information of any nature by wire, radio, optical or other electromagnetic systems.[1][2] Telecommunication Telecommunication occurs when the exchange of information between communication participants includes the use of technology. It is transmitted either electrically over physiical media, such as cables, or via electromagnetic radiation.[3][4][5][6][7][8] Such transmission paths are often divided into communication channels which afford the advantages of multiplexing [...More...]  "Telecommunication" on: Wikipedia Yahoo 

8N1 8N1 is a common shorthand notation for a serial port parameter setting or configuration in asynchronous mode, in which there are eight (8) data bits, no (N) parity bit, and one (1) stop bit.[1] As such, 8N1 is the most common configuration for PC serial communications today. The abbreviation is usually given together with the line speed in bits per second, as in 9600/8N1. The speed includes bits for framing (stop bits, parity, etc.) and the effective data rate is lower than the bit transmission rate. For 8N1 encoding, only 80% of the bits are available for data (for every eight bits of data, ten bits are sent over the serial link — one start bit, the eight data bits, and the one stop bit). This mode was also commonplace for the link between modems until the 1990s when Link Access Procedure for Modems (LAPM) became widespread [...More...]  "8N1" on: Wikipedia Yahoo 

Oscilloscope An oscilloscope, previously called an oscillograph,[1][2] and informally known as a scope or oscope, CRO (for cathoderay oscilloscope), or DSO (for the more modern digital storage oscilloscope), is a type of electronic test instrument that allows observation of varying signal voltages, usually as a twodimensional plot of one or more signals as a function of time. Other signals (such as sound or vibration) can be converted to voltages and displayed. Oscilloscopes are used to observe the change of an electrical signal over time, such that voltage and time describe a shape which is continuously graphed against a calibrated scale. The observed waveform can be analyzed for such properties as amplitude, frequency, rise time, time interval, distortion and others. Modern digital instruments may calculate and display these properties directly [...More...]  "Oscilloscope" on: Wikipedia Yahoo 

Digital Data Digital data, in information theory and information systems, are discrete, discontinuous representations of information or works, as contrasted with continuous, or analog signals which behave in a continuous manner, or represent information using a continuous function. Although digital representations are the subject matter of discrete mathematics, the information represented can be either discrete, such as numbers and letters, or it can be continuous, such as sounds, images, and other measurements. The word digital comes from the same source as the words digit and digitus (the Latin Latin word for finger), as fingers are often used for discrete counting [...More...]  "Digital Data" on: Wikipedia Yahoo 

Second The second is the SI base unit SI base unit of time, commonly understood and historically defined as 1/86,400 of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds each. Another intuitive understanding is that it is about the time between beats of a human heart.[nb 1] Mechanical and electric clocks and watches usually have a face with 60 tickmarks representing seconds and minutes, traversed by a second hand and minute hand. Digital clocks and watches often have a twodigit counter that cycles through seconds [...More...]  "Second" on: Wikipedia Yahoo 