Hi Shaid
I just replaced PIN with another PIN detector from receiver linbrary not APD.I was in hurry so i coudnt changed the down sampling from you detector.You can use that too.APD is another PD,if you use that may you get better results but APD are costlier than PIN.So yu have to take care of that.Nut it is no necessary that you will get better results all the time with APD.