00.20.40.60.811e-171e-151e-131e-111e-91e-71e-50.0010.1extrapolated (dual-Dirac fit)practical measurement flooreye opening 0.43 UIsampling point within the unit interval (UI)bit error rateBathtub curve: measured to 1e-9, extrapolated to 1e-12extrapolated (dual-Dirac fit)measured (1e+11 bits)target BER 1e-12