Fundamental Period of Periodic Signal | Sum of Periodic signals | 1.7

How to calculate fundamental period of a continuous time periodic signal, and how to check whether sum of 2 periodic signals results in a periodic signal, if yes, then what would be the resultant fundamental period, also what is a periodic extension, and a discussion on the single line spectra are the topics addressed in this video.


Following info from
https://en.wikibooks.org/wiki/Signals..., Date accessed 28 Nov,, 2020 is useful


Continuous Signal
A continuous signal is a "smooth" signal, where the signal is defined over a certain range. For example, a sine function is a continuous signal, as is an exponential function or a constant function. A portion of a sine signal over a range of time 0 to 6 seconds is also continuous. Examples of functions that are not continuous would be any discrete signal, where the value of the signal is only defined at certain intervals.


Periodic Signals
A signal is a periodic signal if it completes a pattern within a measurable time frame, called a period and repeats that pattern over identical subsequent periods. The completion of a full pattern is called a cycle. A period is defined as the amount of time (expressed in seconds) required to complete one full cycle. The duration of a period represented by T, may be different for each signal but it is constant for any given periodic signal.


Period

The period is the smallest value of T satisfying g(t + T) = g(t) for all t. The period is defined so because if g(t + T) = g(t) for all t, it can be verified that g(t + T') = g(t) for all t where T' = 2T, 3T, 4T, ... In essence, it's the smallest amount of time it takes for the function to repeat itself. If the period of a function is finite, the function is called "periodic". Functions that never repeat themselves have an infinite period, and are known as "aperiodic functions".

The period of a periodic waveform will be denoted with a capital T. The period is measured in seconds.