Long-Term Average Spectrum

A long-term average spectrum (LTAS) is the time-averaged Power Spectrum computed over many FFT frames, used to characterize persistent spectral content and estimate a stable noise floor.

$$\bar{P}[k]=\frac{1}{M}\sum _{m=0}^{M-1}{P}_m[k]$$

• where $P_m[k]$ is the Power Spectrum at frame $m$ and $M$ is the number of frames.

In real-time processing, the LTAS is often maintained as an Exponential Moving Average over successive frames rather than a finite sum.