First-Order Discrete-Time Wave-Variable Conversion Filters

• First-order difference:
  $${\hat v}(n) = y(n) - y(n-1)$$

• First-order ``leaky'' integrator:
  $${\hat y}(n) = v(n) + g {\hat y}(n-1), \quad g<1, g\approx 1$$
  (loss factor $g$ avoids DC build-up)