We can know the instantaneous frequency from the time-frequency plane directly if the image is clear enough.

The instantaneous frequency of the carrier is directly proportional to the instantaneous value of the input signal.

When the input signal is a chirp function, the instantaneous frequency is a linear function.

Asymptotic wavelet and Gabor analysis: extraction of instantaneous frequencies.

In analog applications, the instantaneous frequency of the carrier is directly proportional to the instantaneous value of the input signal.

Angle modulation is the proper term for modulation by changing the instantaneous frequency or phase of the carrier signal.

The time derivative of the unwrapped instantaneous phase is called the instantaneous frequency:

Having obtained the intrinsic mode function components, the instantaneous frequency can be computed using the Hilbert Transform.

In a linear chirp, the instantaneous frequency varies linearly with time:

This type of modulation employs sinusoidal waveforms whose instantaneous frequency increases or decreases linearly over time.