Signal:

A signal is defined as any physical or virtual quantity that varies with time or space or any other independent variable or variables. Graphically, the independent variable is represented by horizontal axis or x-axis. And the dependent variable is represented by vertical axis or y-axis.

Mathematically, a signal is a function of one or more than one independent variables.


Characteristics Of Signal:

A signal is defined by its characteristics. It shows the nature of the signal. These characteristics are given below:

Amplitude:

Amplitude is the strength or height of the signal waveform. Visually, it is the height of the waveform from its centerline or x-axis. The y-axis of a signal’s waveform shows the amplitude of a signal. The amplitude of a signal varies with time. For example, the amplitude of a sine wave is the maximum height of the waveform on Y-axis

The signal’s strength is usually measured in decibels db.


Frequency:

Frequency is the rate of repetitions of a signal’s waveform in a second.

Periodic signals repeat its cycle after some time. The number of cycles in a second is known as Frequency. The unit of Frequency is hertz (Hz) and one hertz is equal to one cycle per second. It is measured along the x-axis of the waveform. For example, a sine wave of 5 hertz will complete its 5 cycles in a one second.


Time Period

The time period of a signal is the time in which it completes its one full cycle. The unit of the time period is Second. The time period is denoted by ‘T’ and it is the inverse of frequency. I.e.

T=1/F

For example, a sine wave of time period 10 sec will complete its one full cycle in 10 seconds.

Phase:

The phase of a sinusoidal signal is the shift or offset in its origin or starting

point. The phase shift can be lagging or leading. Usually, the original sinusoidal signals have 0° degree phase and start at 0 amplitude but an offset in phase will shift its starting amplitude to other than 0. An example of 45° phase shift is given below. The signal remains the same but its origin is shifted to 45°.

The phase shift can be from 0° to 360° in degrees or 0 to 2Ï€ in radians. 360° degree or 2Ï€ radians is one complete period.







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