I have tested my FX radar unit against my Sky screen and the radar reads 9 fps faster then the sky screen. I graphed the result and the two graphs mimic each other shot for shot just the radar is 9 fps faster. The ES and SD are the same. The radar unit has a feature that is supposed to allow you to calibrate, within plus or minus 2 percent, but I can't make it work. Anyone have this issue and is there a trick to calibrate it?