- 産業: Telecommunications
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ATIS is the leading technical planning and standards development organization committed to the rapid development of global, market-driven standards for the information, entertainment and communications industry.
A mathematical artifice consisting of an impulse of infinite amplitude and zero width, and having an area of unity. Note: The unit impulse is useful for the mathematical expression of the impulse response, i.e., the transfer function, of a device. Synonym Dirac delta function.
Industry:Telecommunications
A mathematical expression (algorithm) describing the net result of the effects of a closed (feedback) loop on the input signal to the circuits enclosed by the loop. Note 1: The closed-loop transfer function is measured at the output. Note 2: The output signal waveform can be calculated from the closed-loop transfer function and the input signal waveform.
Industry:Telecommunications
A mathematical formula or algorithm that constitutes or defines an efficient way of formulating computer graphics. Fractal graphics translate the natural curves of an object into mathematical formulas, from which the entire image can later be constructed. Fractals are self-similar in that any piece of the fractal design contains a miniature of the entire design. A fractal is completely described by (a) one piece (layer) of the design, and (b) a sublayer of the design, which sublayer shows how contiguous pieces (layers) fit together. For this reason, fractal patterns (designs) require very little computer storage space. An example of a fractal is a fern leaf design.
Industry:Telecommunications
A mathematical function that describes Boolean operations. 2. A switching function in which the number of possible values of the function and each of its independent variables is two.
Industry:Telecommunications
A mathematical function that maps values from a large (or even very large) domain into a smaller range, and is (a) one-way in that it is computationally infeasible to find any input which maps to any pre-specified output; and (b) collision-free in that it is computationally infeasible to find any two distinct inputs which map to the same output.
Industry:Telecommunications
A mathematical model of a device that changes its internal state and reads from, writes on, and moves a potentially infinite tape, all in accordance with its present state, thereby constituting a model for computer-like behavior.
Industry:Telecommunications
A mathematical or conceptual representation for specifying and proving system security. Examples: Non-interference model, Information Flow model, Bell-LaPadula model.
Industry:Telecommunications
A mathematical proof of consistency between a specification and its implementation.
Industry:Telecommunications
A mathematical statement of the probability that exactly k discrete events will take place during an interval of length t, expressed by where k is a non-negative integer, e is the base of the natural logarithms (e2. 71828,) is the constant rate that the events occur, and t is the expected number of events occurring during an interval of length t.
Industry:Telecommunications
A mathematical statement that describes the transfer characteristics of a system, subsystem, or equipment. 2. The relationship between the input and the output of a system, subsystem, or equipment in terms of the transfer characteristics. Note 1: When the transfer function operates on the input, the output is obtained. Given any two of these three entities, the third can be obtained. Note 2: Examples of simple transfer functions are voltage gains, reflection coefficients, transmission coefficients, and efficiency ratios. An example of a complex transfer function is envelope delay distortion. Note 3: For a negative feedback circuit, the transfer function, T, is given by where eo is the output, ei is the input, G is the forward gain, and H is the backward gain, i.e., the fraction of the output that is fed back and combined with the input in a subtracter. 3. Of an optical fiber, the complex mathematical function that expresses the ratio of the variation, as a function of modulation frequency, of the instantaneous power of the optical signal at the output of the fiber, to the instantaneous power of the optical signal that is launched into the fiber. Note: The optical detectors used in communication applications are square-law devices. Their output current is proportional to the input optical power. Because electrical power is proportional to current, when the optical power input drops by one-half (3 dB,) the electrical power at the output of the detector drops by three-quarters (6 dB. )
Industry:Telecommunications
