文档介绍：Chapter 2
Signals and Spectra
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Introduction
Basic signal properties(dc, rms,dBm, and power)
Fourier transform and spectra
Linear systems and linear distortion
Bandlimited signal and sampling
Discrete Fourier transform
Bandwidth of signal
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Properties of signal and Noise (Properties of Physical Waveform)
the waveform has significant nonzero values over posite time interval that is finite
The spectrum of the waveform has significant values over posite frequency interval that is finite
The waveform is a continuous function of time
The waveform has a finite peak value
The waveform has only real values. That is, at any time, it cannot have plex value a+bj, where b is nonzero.
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Properties of signal and Noise
4
Properties of signal and Noise
Time average operator
Periodic waveform with period T0
Time average operator for periodic waveform
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Properties of signal and Noise
Dc value
Instantaneous Power
Average Power
Theorem. If a load is resistive, the average power is :
Where R is value of the resistive load
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Properties of signal and Noise
Rms Value
Periodic waveform with period T0
Time average operator for periodic waveform
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Properties of signal and Noise
Example 2-1(p37)
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Properties of signal and Noise
Average normalized power
total normalized energy
Power waveform ω(t) is a power waveform if and only if the average normalized power P is finite and nonzero (. 0<P<∞)
Energy waveform ω(t) is a energy waveform if and only if the average total normalized energy E is finite and nonzero (. 0<E<∞)
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Properties of signal and Noise
Decibel(dB) this is a base 10 logarithmic measure of power ratios, for a circuit,
In Engineering Practice:
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