About signal analysis?

Question

Is the following description correct?

Time Domain Analysis
x axis (time) against y axis (amplitude)

Frequency Domain Analysis
x axis (frequency) against y axis (amplitude)

Frequency domain analysis = spectrum domain analysis = find out the signal's spectrum?

Answer 1

Your description is correct.

Time domain analysis of a signal deals with how the amplitude of a signal varies with time. You can measure parameters such as the periodic time, frequency and phase of a signal using time domain analysis.

For simple signals (such as single frequency sine/cosine wave signal) time domain analysis is usually enough to obtain most details. However, if the signal is of an arbitrary form (in time domain), then it may be difficult to analyze it in time domain.

This is where the frequency domain analysis comes in. By transforming the time domain signal into frequency domain, the Frequency Vs. Amplitude graph shows what frequencies are contained within the artbitrary shaped time domain signal.

For example, if you have a simple 100 Hz sine wave and you transform it to frequency domain, then you will see a large amplitude only at frequency=100 Hz and almost zero or an extremely small values at all other frequencies. But if you look at the frequency-amplitude graph of a 100Hz Square Wave, then you will notice a large value at 100Hz, plus decreasing amplitudes at 300Hz, 500Hz, 700Hz etc...because a Square wave consists of what is known as the 'Harmonics' of the sine wave at original 100Hz, at odd multiples. i.e 100Hz, 300Hz, 500Hz..etc.

Hope this helps.

Answer 2

It is correct.

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