the disclosed quadrature decoder filtering circuitry for motor control uses one quadrature signal to correct an error in the other quadrature signal , thus allowing a noisy signal due to large dust particles or scratches to be recovered . in some implementations , a system processing for quadrature signals comprises a first circuitry triggered by edges of a first quadrature signal to detect inactivity of a second quadrature signal during consecutive edges of the first quadrature signal . a second circuitry is operable to count the number of consecutive edges of the first quadrature signal during inactivity of the second quadrature signal . a third circuitry is operable to combine transitions of the first quadrature signal with the second quadrature signal during a period of time determined by the count value of the second circuitry .