Analyzing Signals - Principles of Communication

What is Analyzing Signals?

To analyze a signal, it has to be signified. This representation in communication systems is of two kinds −

  • Frequency domain representation, and
  • Time domain representation.

Think through two signals with 1 kHz and 2 kHz frequencies. Both of them are signified in time and frequency domain as shown in the resulting figure.


Time domain analysis, gives the signal behavior over a definite time period. In the frequency domain, the signal is examined as a mathematical function with respect to the frequency.

Frequency domain demonstration is necessary where the signal processing such as filtering, amplifying and mixing are done.
For example, if a signal such as the resulting is considered, it is understood that noise is present in it.


The frequency of the original signal may be 1 kHz, but the noise of certain frequency, which perverts this signal, is unidentified. Though, when the same signal is signified in the frequency domain, using a spectrum analyzer, it is planned as shown in the resulting figure.

At this time, we can notice few harmonics, which signify the noise presented into the original signal. Therefore, the signal representation helps in analyzing the signals.

Frequency domain analysis helps in making the preferred wave patterns. For instance, the binary bit patterns in a computer, the Lissajous patterns in a CRO, etc. Time domain investigation helps to understand such bit patterns.

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