严厉批评
发表于 2025-3-28 15:37:40
Introductionen used to convey information throughout recorded history, and both Greeks and Romans employed light beacons in the pre-Christian era. A chain of beacons was used by the English in 1588 to warn of the approaching Spanish Armada, and about this time the word ‘signal’ came into general use to denote ‘
Derogate
发表于 2025-3-28 19:57:20
Periodic Signalsf signal theory in terms of time and of frequency. A periodic signal will therefore be considered to be one which repeats itself exactly every . seconds, where . is called the period of the signal waveform; the theoretical treatment of periodic waveforms assumes that this exact repetition is extende
DEI
发表于 2025-3-29 01:02:19
Aperiodic Signalse spectrum of such a signal consists of a number of discrete frequencies and is known as a ‘line’ spectrum. Although the analysis of periodic signals gives results which can be of great practical interest, the great majority of signals are not of this type. Firstly, even signals which repeat themsel
艰苦地移动
发表于 2025-3-29 04:41:47
Sampled-Data Signalsntly. In recent years such signals have come to assume great importance because of developments in digital electronics and computing. Since it is not possible to feed continuous data into a digital (as opposed to analogue) computer, any signal or data input must be represented as a set of numerical
Collar
发表于 2025-3-29 10:55:20
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Gustatory
发表于 2025-3-29 15:16:17
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Interstellar
发表于 2025-3-29 16:12:55
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nonchalance
发表于 2025-3-29 22:59:43
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造反,叛乱
发表于 2025-3-30 02:12:17
Signal Recovery, Detection and Predictiontracting a signal from random noise: it arises to some extent in almost all communication, measurement and recording situations. Another interesting problem is that of predicting the future of a random signal as accurately as possible. Not surprisingly, we shall find the earlier discussions of rando