Jitter on NEC3500 2.TG

Hi

Could anyone please explain why when i burn with my NEC3500 drive im always gettin the same kind of jitter pattern. A major rise around the 500mb mark.

Is there anyway to resolve this and is it of any concern? If i burn the same media with my BenQ drive i get a much smoother jitter line than the high increase around 500mb which i get from the NEC drive.

I think that the drive is speeding up (write) in this area from 0 to 1GB.