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Frequency Modulation
In telecommunications and signal processing, frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. In analog frequency modulation, such as FM radio
FM radio
broadcasting of an audio signal representing voice or music, the instantaneous frequency deviation, the difference between the frequency of the carrier and its center frequency, is proportional to the modulating signal. Digital data can be encoded and transmitted via FM by shifting the carrier's frequency among a predefined set of frequencies representing digits - for example one frequency can represent a binary 1 and a second can represent binary 0. This modulation technique is known as frequency-shift keying (FSK)
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Differential Manchester Encoding
Differential Manchester encoding
Differential Manchester encoding
is a line code in which data and clock signals are combined to form a single 2-level self-synchronizing data stream. In various specific applications, this line code is also called by various other names, including Biphase Mark Code (CC), Frequency Modulation (FM), F2F (frequency/double frequency), Aiken Biphase, and Conditioned diphase.[1] It is a differential encoding, using the presence or absence of transitions to indicate logical value
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Line Code
Some signals are more prone to error than others when conveyed over a communication channel as the physics of the communication or storage medium constrains the repertoire of signals that can be used reliably.[1] The repertoire of signals is usually called a constrained code in data storage systems. In telecommunication, a line code is a code chosen for use within a communications system for transmitting a digital signal down a transmission line. Line or constrained coding generates the repertoire of allowed digital signals to be transported, with a waveform or set of allowed waveforms that is appropriate for the specific properties of the physical channel and of the receiving equipment
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Fax Modem
A fax modem enables a computer to transmit and receive documents as faxes on a telephone line. A fax modem is like a data modem but is designed to transmit and receive documents to and from a fax machine or another fax modem. Some, but not all, fax modems do double duty as data modems. As with other modems, fax modems can be internal or external. Internal fax modems are often called fax boards. In the early 1990s small business PCs commonly had a PC-based fax/modem card and fax software (typically Win Fax
Fax
Pro). Largely replaced by email, PC-based faxing with a fax/modem declined at the turn of the century. Where faxing from a PC is required there are a number of Internet-based faxing alternatives
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Binary Number
In mathematics and digital electronics, a binary number is a number expressed in the base-2 numeral system or binary numeral system, which uses only two symbols: typically 0 (zero) and 1 (one). The base-2 numeral system is a positional notation with a radix of 2. Each digit is referred to as a bit
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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
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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
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Information
Information
Information
is any entity or form that resolves uncertainty or provides the answer to a question of some kind. It is thus related to data and knowledge, as data represents values attributed to parameters, and knowledge signifies understanding of real things or abstract concepts.[1] As it regards data, the information's existence is not necessarily coupled to an observer (it exists beyond an event horizon, for example), while in the case of knowledge, the information requires a cognitive observer.[citation needed] Information
Information
is conveyed either as the content of a message or through direct or indirect observation
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Signal Processing
Signal
Signal
processing concerns the analysis, synthesis, and modification of signals, which are broadly defined as functions conveying "information about the behavior or attributes of some phenomenon",[1] such as sound, images, and biological measurements.[2] For example, signal processing techniques are used to improve signal transmission fidelity, storage efficiency, and subjective quality, and to emphasize or detect components of interest in a measured signal.[3]Contents1 History 2 Application fields 3 Typical devices 4 Mathematical methods applied 5 Categories5.1 Analog signal processing 5.2 Continuous-time signal processing 5.3 Discrete-time signal
Discrete-time signal
processing 5.4 Digital signal processing 5.5 Nonlinear signal processing6 See also 7 Notes and references 8 External linksHistory[edit] According to Alan V. Oppenheim and Ronald W
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General Electric
General Electric
General Electric
(GE) is an American multinational conglomerate incorporated in New York[5] and headquartered in Boston, Massachusetts.[2] As of 2016, the company operates through the following segments: aviation, current, digital, energy connections, global research, healthcare, lighting, oil and gas, power, renewable energy, transportation, and capital which cater to the needs of financial services, medical devices, life sciences, pharmaceutical, automotive, software development and engineering industries.[6] In 2017, GE ranked among the Fortune 500
Fortune 500
as the thirteenth-largest firm in the U.S
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Radio Frequency Interference
Electromagnetic interference
Electromagnetic interference
(EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction.[1] The disturbance may degrade the performance of the circuit or even stop it from functioning. In the case of a data path, these effects can range from an increase in error rate to a total loss of the data.[2] Both man-made and natural sources generate changing electrical currents and voltages that can cause EMI: ignition systems, cellular network of mobile phones, lightning, solar flares, and auroras (Northern/Southern Lights)
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Delta-sigma Modulation
Delta-sigma (ΔΣ; or sigma-delta, ΣΔ) modulation is a method for encoding analog signals into digital signals as found in an analog-to-digital converter (ADC). It is also used to convert high bit-count, low-frequency digital signals into lower bit-count, higher-frequency digital signals as part of the process to convert digital signals into analog as part of a digital-to-analog converter (DAC). In a conventional ADC, an analog signal is sampled with a sampling frequency and subsequently quantized in a multi-level quantizer into a digital signal. This process introduces quantization error noise. The first step in a delta-sigma modulation is delta modulation. In delta modulation the change in the signal (its delta) is encoded, rather than the absolute value. The result is a stream of pulses, as opposed to a stream of numbers as is the case with pulse code modulation (PCM)
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Pulse-width Modulation
Pulse-width modulation
Pulse-width modulation
(PWM), or pulse-duration modulation (PDM), is a modulation technique used to encode a message into a pulsing signal. Although this modulation technique can be used to encode information for transmission, its main use is to allow the control of the power supplied to electrical devices, especially to inertial[definition needed] loads such as motors. In addition, PWM is one of the two principal algorithms used in photovoltaic solar battery chargers,[1] the other being maximum power point tracking. The average value of voltage (and current) fed to the load is controlled by turning the switch between supply and load on and off at a fast rate
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Pulse-code Modulation
Pulse-code modulation
Pulse-code modulation
(PCM) is a method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications
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Pulse-amplitude Modulation
Pulse-amplitude modulation
Pulse-amplitude modulation
(PAM), is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulse. It is an analog pulse modulation scheme in which the amplitudes of a train of carrier pulses are varied according to the sample value of the message signal
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Polar Modulation
Polar modulation is analogous to quadrature modulation in the same way that polar coordinates are analogous to Cartesian coordinates. Quadrature modulation makes use of Cartesian coordinates, x and y. When considering quadrature modulation, the x axis is called the I (in-phase) axis, and the y axis is called the Q (quadrature) axis. Polar modulation makes use of polar coordinates, r (amplitude) and Θ (phase). The quadrature modulator approach to digital radio transmission requires a linear RF power amplifier
RF power amplifier
which creates a design conflict between improving power efficiency or maintaining amplifier linearity. Compromising linearity causes degraded signal quality, usually by adjacent channel degradation, which can be a fundamental factor in limiting network performance and capacity
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