7.2. 1 Windows function method o One commonly used approximation criterion is to minimize the integral -squared error R2兀 ∫H1(2)-Hl() do Where H(0)=∑hem n=-M7.2.1 Windows function method  One commonly used approximation criterion is to minimize the integral-squared error ( ) ( ) 1 2 2 j j R t d H e H e d       −  = −  ( )   M j j n t t n M H e h n e   − = − =  where