Seagate ST31000640SSIM manual Receive eye mask, Jitter tolerance masks, Absolute amplitude

9.5.2.1.2Receive eye mask

Figure 16 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

0V -Z1 -Z2

0X1 X2 1-X1 1

1-X2

Normalized time (in UI)

Figure 16. 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.

9.5.2.1.3Jitter tolerance masks

Figure 17 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 in table 18 and X1TOL is half the value for total jitter in table 19, for jitter frequencies above ((bit rate) / 1.667).

Absolute amplitude (in V)

Z2

Z1OP

Z1TOL

0 V

-Z1TOL -Z1OP

-Z2

(additional sinusoidal jitter) / 2

				Outline of eye mask
				before adding
				sinusoidal jitter
				Outline of eye mask
				after adding
				sinusoidal jitter
0 X1OP	X2	1
			1-X1OP
X1TOL		1-X1TOL

Normalized time (in UI)

Figure 17. Receive tolerance eye mask

Barracuda ES.2 SAS Product Manual, Rev. G 61