18
TEST & MEASUREMENT
Multimode Ethernet Fibre Type 62.5/125 μm 50/125 μm Applications Fibre Standard TIA 492AAAA
(OM1) TIA 492AAAB
(OM2) TIA 492AAAC
(OM3) TIA 492AAAD
(OM4)
Nominal wavelength (nm) 850 1300 850 1300 850 1300 850 1300
4.0
Application
Parameter
Channel attenuation (dB)
Ethernet 10/100BASE-SX
Ethernet 100BASE-FX
- 4.0 - 4.0 - 4.0 -
300
(984) - 300
(984) - 300
(984) - 300
(984) -
Channel attenuation (dB) - 11.0 - 6.0 - 6.0 - 6.0
Supportable distance m (ft) - 2000
(6560) - 2000
(6560) - 2000
(6560) - 2000
(6560)
2.6
Supportable distance m (ft)
Channel attenuation (dB)
Ethernet 1000BASE-SX
Ethernet 1000BASE-LX
- 3.6 - - - - -
275
(900) - 550
(1804) - Note 1 - Note 1 -
Channel attenuation (dB) - 2.3 - 2.3 - 2.3 - 2.3
Supportable distance m (ft) - 550
(1804) - 550
(1804) - 550
(1804) - 550
(1804)
2.4
Supportable distance m (ft)
Channel attenuation (dB)
Ethernet 10GBASE-S
Ethernet 10GBASE-LX4
Ethernet 10GBASE-LRM
Ethernet 40GBASE-SR4
Ethernet 100GBASE-SR4
Ethernet 100GBASE-SR10
850 nm laser-optimized 50/125 μm
- 2.3 - 2.6 - 2.9 -
33
(108) - 82
(269) - 300
(984) - 400
(1312) -
Channel attenuation (dB) - 2.5 - 2.0 - 2.0 - 2.0
Supportable distance m (ft) - 300
(984) - 300
(984) - 300
(984) - 300
(984)
Channel attenuation (dB) - 1.9 - 1.9 - 1.9 - 1.9
Supportable distance m (ft) - 220
(720) - 220
(720) - 220
(720) - 220
(720)
Channel attenuation (dB) - - - - 1.9 - 1.5 2 -
Supportable distance m (ft) - - - - 100
(328) - 150
(492) -
Channel attenuation (dB) - - - - 1.9 - 1.9 -
- 100
(328) -
Supportable distance m (ft)
Supportable distance m (ft) - - - - 70
(230) Channel attenuation (dB) - - - - 1.9 - 1.5 2 -
Supportable distance m (ft) - - - - 100
(328) - 150
(492) -
Receiver Sensitivity is the weakest (darkest) signal the
receiver can detect and the dynamic range is how much
brighter than the sensitivity specification the light can be
without blinding the receiver. For example, a receiver with
a sensitivity of -30dBm and a dynamic range of 20dB can
detect light within a range of -10 to -30dBm.
The diagram on the right should help to visualise the
scenario. If the transmitter injects light into the fibre at
-20dBm, and the weakest light the receiver can detect is
-30dBm, the difference between the two is 10dB. Meaning
that the system can have at most 10dB of loss before the
signal is too weak for the receiver to detect. But what if the
receiver was paired with a transmitter that output -5dBm of
power? The signal would be too strong and overpower the
receiver. With optical systems, care must be taken to not
overdrive receivers because it will be just as detrimental as
having too little signal. n
0 dBm
-10dBm
-20dBm
-30dBm
Transmitter output
-20 dBm
Receiver sensitivity
-30 dBm
-40dBm
-50dBm
www.networkseuropemagazine.com
Receiver dynamic range 20 dB
It can operate between -10 and -30 dBm