Signals and Systems.
You can learn basic ideas about signals in below videos. Check this out.
Signals- Basics
Introduction- https://youtu.be/PB60cyn5K_Y
Classification of Signals-Part1- https://youtu.be/X10gNeEuaI8
Classification of Signals-Part2- https://youtu.be/qHvl0sqWJ4Q
Standard Signals-Part 1-Unit Step,Unit Impulse and Unit Ramp Function
https://youtu.be/dQYQI_lXzVU
Standard Signals-Part 2-Unit Parabolic Function, Exponential Signal and Sinusoidal Signal
https://youtu.be/KLpGvkkpON4
Standard Signals-Part 3-Rectangular ,Triangular,Signum ,Sinc,and Gaussian Function
https://youtu.be/sPfPdSD-4ws
Basic Signal Operations-Part 1- https://youtu.be/yIlZ6aYXorQ
Basic Signal Operations-Part 2- https://youtu.be/8nETnM3OSd8

Basic Engineering_Applied Mechanics#TANGEDCO AE Exam. Iam an IAS academy notes

Maths & Aptitude previous year GATE QUESTIONS. Click the link below

https://drive.google.com/file/d/1LxbiX0E0hOsqpZoxnkq6h0hqcgMX-Znv/view?usp=drivesdk

for gate preparation 👆👆