Frequenrate
Frequenrate is a metric used in signal analysis to describe how quickly the frequency content of a signal changes over time. Denoted FR(t), it is the time derivative of the instantaneous frequency f_inst(t). The concept combines the idea of frequency with a rate of change and is typically expressed in units of hertz per second (Hz/s).
For a signal s(t) with an analytic representation s_a(t) = A(t) e^{i φ(t)} obtained via the Hilbert transform,
Interpretation and use: A signal with a constant frequency has FR = 0. If the frequency changes
Limitations: Accurate estimation of FR depends on reliable phase unwrapping and noise suppression; numerical differentiation can