## Momentary frequency

Purpose

Description

Tips

Macro Synopsis

Modules

Related Functions

References

### Purpose

Momentary frequency

### Description

"Momentary frequency" belongs to the group of adaptive estimators and
computes the momentary frequency of the input signal x by counting
zero-crossings.

Parameters are:

- Adaptation time
`tm` for the mean estimator
- Adaptation time
`tf` for the frequency estimator

Both parameters are in x-axis units.

### Tips

The parameters for the adaptation times of the estimators determine the adaptation speed and the robustness of the estimation procedure. Lower values result in higher adaptation speeds but then the estimated quantity varies around the true value with high variance. Higher values result in lower adaptation speeds, but then the quantity to be estimated converges more smoothly to the true value in the case of stationary signals. For a momentary frequency analysis of narrow-band signals a time derivation of the Instantaneous phase usually yields better results due to its time resolution.

### Macro Synopsis

`y = MomFreq(x,tm,tf);`

signal x,y;

float tm,tf;

### Modules

Filter

### Related Functions

Momentary ARMA bandpower, Momentary ARMA coherence,
ARMA dependence, Momentary ARMA spectrum,
Momentary bandpower, Momentary mean, Momentary power.

### References

Haykin [41], Grieszbach et al. [43]