Amplitude tracking

• Tracking linear amplitude by adjusting $\hat{a}$ given correct model phase $\phi(n)$, large frequency $\Omega$ and fixed model amplitude at block boundary $A_0$.
  
  $$e = \sum_n ((A +an) cos(\phi(n)) - (A_0 +\hat{a}n) cos(\phi(n)))^2 = \hbox{Min}$$
  
  

• For optimal $\hat{a}$ amplitude error depends on initial amplitude error and position inside the block.

  
  

  $$\Delta_A(x) \approx \Delta_A(0) (1- \frac{3x}{2})$$