Fourier time series analysis helps in decomposing a complex signal into its constituent frequencies, allowing for better understanding of the signal's frequency content. This analysis is fundamental in areas like signal filtering, spectral analysis, and noise reduction in signal processing. It also aids in identifying and isolating specific frequency components within a signal.
Fourier series analysis is useful in signal processing as, by conversion from one domain to the other, you can apply filters to a signal using software, instead of hardware. As an example, you can build a low pass filter by converting to frequency domain, chopping off the high frequency components, and then back converting to time domain. The sky is the limit in terms of what you can do with fourier series analysis.
Fourier analysis Frequency-domain graphs
An aperiodic signal cannot be represented using fourier series because the definition of fourier series is the summation of one or more (possibly infinite) sine wave to represent a periodicsignal. Since an aperiodic signal is not periodic, the fourier series does not apply to it. You can come close, and you can even make the summation mostly indistinguishable from the aperiodic signal, but the math does not work.
The Fourier series can be used to represent any periodic signal using a summation of sines and cosines of different frequencies and amplitudes. Since sines and cosines are periodic, they must form another periodic signal. Thus, the Fourier series is period in nature. The Fourier series is expanded then, to the complex plane, and can be applied to non-periodic signals. This gave rise to the Fourier transform, which represents a signal in the frequency-domain. See links.
The fourier transform is used in analog signal processing in order to convert from time domain to frequency domain and back. By doing this, it is easier to implement filters, shifters, compression, etc.
A Fourier series is a set of harmonics at frequencies f, 2f, 3f etc. that represents a repetitive function of time that has a period of 1/f. A Fourier transform is a continuous linear function. The spectrum of a signal is the Fourier transform of its waveform. The waveform and spectrum are a Fourier transform pair.
Spectral analysis of a repetitive waveform into a harmonic series can be done by Fourier analyis. This idea is generalised in the Fourier transform which converts any function of time expressed as a into a transform function of frequency. The time function is generally real while the transform function, also known as a the spectrum, is generally complex. A function and its Fourier transform are known as a Fourier transform pair, and the original function is the inverse transform of the spectrum.
Albert A. Gerlach has written: 'Role of the sectionalized Fourier transform in high-speed coherence processing' -- subject(s): Digital techniques, Fourier transform spectroscopy, Signal processing 'Theory and applications of statistical wave-period processing' -- subject(s): Radar, Random noise theory, Signal theory (Telecommunication), Sonar
Every periodic signal can be decomposed to a sum (finite or infinite) of sines and cosines according to fourier analysis.
A huge practical application of trig is Fourier series. Fourier series says you can represent any periodic function as a sum of infinite sines and cosines. By constructively/destructively overlapping different frequencies with specific amplitudes, you can mimic a function, or signal, or different types of boundary conditions. With more terms, aka more frequencies, you get closer and closer to the actual function. Fourier series is the only way to solve some types of differential equations. In digital signal processing, fourier series is extremely important because it gives the option of changing a time domain signal into a frequency domain signal. This allows you to manipulate signals in ways one couldn't imagine. Its used in filters, compression, data transmission, etc. The end results affect cell phones, televisions, any kind of digital filter, etc...
Spectral disturbance refers to irregularities or variations in the frequency composition of a signal or phenomenon. In the context of data analysis or signal processing, it often indicates anomalies, interference, or noise that can affect the reliability or accuracy of measurements or observations. Spectral disturbance can be identified through spectral analysis techniques such as Fourier transforms.
The Fourier series is important because it allows one to model periodic signals as a sum of distinct harmonic components. In other words, representing signals in this way allows one to see the harmonics in a signal distinctly, which makes it easy to see what frequencies the signal contains in order to filter/manipulate particular frequency components.