Improving template with instantaneous amplitude

1. What is instantaneous amplitude?
2. Why is instantaneous frequency important?
3. What type of signal does not have instantaneous change in its amplitude?

What is instantaneous amplitude?

peak amplitude (often shortened to simply ``amplitude''): the nonnegative value of the waveform's peak. instantaneous amplitude: the value of (either positive or negative) at any time .

Why is instantaneous frequency important?

The instantaneous frequency (IF) of a signal is a parame- ter which is often of significant practical importance. In many situations such as seismic, radar, sonar, communications, and biomedical applications, the IF is a good descriptor of some physical phenomenon.

What type of signal does not have instantaneous change in its amplitude?

Phase signals (PSs) are the basic elements of phase or frequency modulation and this shows their importance. They are real signals with constant instantaneous amplitude. They are characterized by a canonical pair [1, ϕ(t)] or by a unique function ϕ(t) such that exp[jϕ(t)] is an AS.