This video is an introduction to angle modulation which includes frequency and phase modulation. This video discusses a new concept called instantaneous frequency, which is not an immediately obvious concept. However, the instantaneous frequency concept is highly related to angle modulation bandwidth.
The information in this video will help you understand concepts found in "Modern Digital and Analog Communication" by B.P. Lathi and Zhi Ding.
You can purchase this textbook here:
https://www.amazon.com/Digital-Commun...