Nortel Networks 450 - Manual (Page 246)

Using the BayStack 450 10/100/1000 Series Switch
B-6 302401-D Rev 00
Worst-Case Power Budget and Penalties
Table B-8 lists the worst-case power budget and penalties for the 1000BASE-LX
models:
Receive sensitivity – 19 dBm
Return loss (minimum) 12 dB
Stressed receive sensitivity 1 , 2 – 14.4 dBm
Receive electrical 3 dB upper cutoff frequency (maximum) 1500 MHz
Vertical eye-closure penalty 3 2.60 dB
1 Measured with conformance test signal at TP3 (see IEEE 802.3, Clause 38.6.11) for BER = 10 –12 at the eye center.
2 Measured with a transmit signal having a 9 dB extinction ratio. If another extinction ratio is used, the stressed receive
sensitivity should be corrected for the extinction ratio penalty.
3 Vertical eye-closure penalty is a test condition for measuring stressed receive sensitivity. It is not a required
characteristic of the receiver.
Note: The link power penalties ( Table B-8 ) are used for link power budget
calculations only. They are not requirements and are not meant to be tested.
Table B-8. Worst-Case 1000BASE-LX Power Budget and Penalties
Parameter 62.5 um MMF 50 um MMF 10 um SMF Unit
Modal bandwidth as measured at
1300 nm (minimum, overfilled launch) 500 400 500 N/A MHz · km
Link power budget 7.5 7.5 7.5 8.0 dB
Operating distance 550 550 550 5000 m
Channel insertion loss 2.35 2.35 2.35 4.57 dB
Link power penalties 3.48 5.08 3.96 3.27 dB
Unallocated margin in link power budget 1.67 0.07 1.19 0.16 dB
Table B-7. 1000BASE-LX Receive Characteristics (continued)
Description Value Units
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