FIRDisplay


    Introduction

    FIRDisplay allows a quick inspection of the result of applying a FIR Filter to a given waveform. FIR stands for finite impulse response. What this means is that the response to a unit impulse is finite in duration. It is a linear filter which means FIR stands for finite impulse response. What this means is that the response to a unit impulse is finite in duration. More precisely, the FIR filter has its response y(t) given by
    y(t) = N
    å
    i = 0 
    		 bi ×x( t - i)
    where the bi's are the impulse response cofficients.

    This application was implemented using the FIRFilter class

    Below we see an unit impulse input at t=2

    FIR_Unit.jpg

    Next we see the response with the coefficients 1.0, 0.8. 0.6, 0.4. 0.2, that is b0=1.0, b1=0.8, etc.

    FIR_UnitResponse.jpg

    Note at t=2, the we first encounter the impulse and our response is b0=1.0. Next, at t=3, the impulse is now one unit back in time and hence b1=0.8 is applied to the unit value to obtain 0.8 at t=3. Etc.

    Next, for the fun we have an imput of the word "three"

    FIR_three.jpg

    and applying the above filter we obtain

    FIR_threeResponse.jpg

    Note, the noise has been modulateD.