Acknowledgment signals can be divided into energy signals and power signals according to their strengths. Power signals can be divided into periodic signals and aperiodic signals according to whether they are periodic or not. The energy signal is finite in amplitude and duration, its energy is finite, and its average power (over an infinite amount of time) is zero. The duration of the power signal is infinite, so its energy is infinite.
The properties of a certain signal can be studied in both the frequency domain and the time domain.
There are four kinds of signal properties in the frequency domain: spectrum, spectral density, energy spectral density and power spectral density. The waveform of the periodic power signal can be represented by the Fourier series, and the items of the series constitute the discrete spectrum of the signal, and its unit is V. The waveform of the energy signal can be represented by the Fourier transform, and the function obtained by the waveform transformation is The spectral density of a signal, its unit is V/Hz. As long as the impulse function is introduced, we can also find its spectral density for a power signal. The energy spectral density is the distribution of the energy of the energy signal in the frequency domain, and its unit is J/Hz. The power spectral density is the distribution of the power of the power signal in the frequency domain, and its unit is W/Hz.
It is known that the characteristics of the signal in the time domain mainly include the autocorrelation function and cross-correlation function. The autocorrelation function reflects the degree of correlation between the values of a signal at different times. The autocorrelation function R(0) of the energy signal is equal to the energy of the signal; and the autocorrelation function R(0) of the power signal is equal to the average power of the signal. The cross-correlation function reflects the degree of correlation between the two signals, which is independent of time and only related to the time difference, and the cross-correlation function is related to the order in which the two signals are multiplied. The autocorrelation function of the energy signal and its energy spectral density constitute a pair of Fourier transforms. The autocorrelation function of the periodic power signal and its power spectral density form a pair of Fourier transforms. The cross-correlation function of the energy signal and its cross-energy spectral density constitute a pair of Fourier transforms. The periodic power signal’s cross-correlation function and its cross-power spectrum make up a pair of Fourier transforms.
The confirmed signal is roughly the above brief introduction. I hope this article can help you to increase your knowledge. Besides this article if you’re looking for a good optical fiber communication equipment manufacturer company you may consider about us.
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