Seagate Cheetah 15K Product Manual page 73

9.5.2.1.2 Receive eye mask
Figure 18 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 X 1 X 2
1-X2
Normalized time (in UI)
Figure 18. 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 19 describes the receive tolerance eye masks and is constructed using the X2 and Z2 values given in
table 31. X1 is half the value for total jitter intable 31 and X1
OP
jitter frequencies above ((bit rate) / 1.667).
Absolute
amplitude
(in V)
Z2
Z1
OP
Z1
TOL
0 V
-Z1
TOL
-Z1
OP
-Z2
0 X1
OP
X1
TOL
Normalized time (in UI)
Figure 19. Receive tolerance eye mask
Cheetah 15K.6 SAS Product Manual, Rev. B
1-X1 1
(additional sinusoidal jitter) / 2
Outline of eye mask
Outline of eye mask
X 2 1
1-X1
OP
1-X1
TOL
is half the value for total jitter in table 32, for
TOL
before adding
sinusoidal jitter
after adding
sinusoidal jitter
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