Seagate ST336754SS Cheetah 15K.4 SAS Product Manual - Page 73

9.5.2.1.2 Receive eye mask Figure 23 describes the receive eye mask. This eye mask applies to jitter after the application of a single pole high-pass frequency-weighting function that progressively attenuates jitter at 20 dB/decade below a frequency of ((bit rate) / 1.667). Absolute amplitude (in V) Z2 Z1 0 V -Z1 -Z2 0 X1 X2 1-X1 1 1-X2 Normalized time (in UI) Figure 23. Receive eye mask Verifying compliance with the limits represented by the receive eye mask should be done with reverse channel traffic present in order that the effects of crosstalk are taken into account. 9.5.2.1.3 Jitter tolerance masks Figure 24 describes the receive tolerance eye masks and is constructed using the X2 and Z2 values given in table 18. X1OP is half the value for total jitter intable 18 and X1TOL is half the value for total jitter in table 19, for jitter frequencies above ((bit rate) / 1.667). Absolute am plitude (in V) (additional sinusoidal jitter) / 2 Z2 Z1OP Z1TOL 0 V -Z1TOL -Z1OP -Z2 0 X1OP X2 1 1-X1OP X1TOL 1-X1TOL Normalized time (in UI) Outline of eye mask before adding sinusoidal jitter Outline of eye mask after adding sinusoidal jitter Figure 24. Reveive tolerance eye mask Cheetah 15K.4 SAS Product Manual, Rev. B 63