Upgrades To Network Speeds May Have Problems On Older Fibers
Practically every network operator wants to upgrade speeds because it's cheaper than installing more fiber. But sometimes it causes problems, and even worse if it involves mixing fiber types.
Practically every network operator wants to upgrade speeds because it's cheaper than installing more fiber. But sometimes it causes problems, and even worse if it involves mixing fiber types.
Here is another conversation we had this month with FOA Master Instructor Joe Botha of Triple Play Fiber Optics in South Africa.
FOA: We have a question on one of the FOAβs social media sites about problems with fusion spliced G.652 and G.657 fiber. Supposedly the loss of the
FOA: We have a question on one of the FOAβs social media sites about problems with fusion spliced G.652 and G.657 fiber. Supposedly the loss of the
higher speed data?
Joe B: The very same problem is experienced locally, where network providers are struggling with their 40G to 200G transmission, and it has nothing to do with attenuation. Put simply, they are using the wrong fiber, G.652D and G.657.A2 instead of G.655
Joe B: The very same problem is experienced locally, where network providers are struggling with their 40G to 200G transmission, and it has nothing to do with attenuation. Put simply, they are using the wrong fiber, G.652D and G.657.A2 instead of G.655
or G.656 fiber.
The dispersion coefficient for G.652D and G.657.A2 is too high and at 40G, you are unlikely to go much further than 4km, without running errors. It varies from 16.9 to 18.2 ps/nm.km at 1550 nm. It is worth noting that for G.655 and G.656 fiber, it varies from
The dispersion coefficient for G.652D and G.657.A2 is too high and at 40G, you are unlikely to go much further than 4km, without running errors. It varies from 16.9 to 18.2 ps/nm.km at 1550 nm. It is worth noting that for G.655 and G.656 fiber, it varies from
as low as 2.6 to 6.0 ps/nm.km at 1550 nm.
New sophisticated modulation techniques such as dual-polarized quadrature phase-shift keying (DP-QPSK) using coherent detection, yields high quality CD compensation. However, because of the added signal processing time
New sophisticated modulation techniques such as dual-polarized quadrature phase-shift keying (DP-QPSK) using coherent detection, yields high quality CD compensation. However, because of the added signal processing time
(versus simple on-off keying) they require, this can potentially be a poor choice from a latency perspective.
FOA: Since most 40G is 4X10G, this probably applies to 10G too, right?
FOA: Since most 40G is 4X10G, this probably applies to 10G too, right?
Joe B:Yes, 10G (max dispersion = 800 ps/nm) is 16x less sensitive to CD than 40G (max dispersion = 50 ps/nm). G.652 and G.657βs CD coefficient is too high in the C and L-bands, making them not perfectly suited for higher speed data, and of course DWDM. G.652 is perfect for CWDM,
but one is not able to run CWDM on either G.655 & G.656, because of their too high cut-off wavelengths: β€ 1480 nm and β€ 1450 nm respectively.
What the guys often do locally in the Metroβs, is to install hybrid cables. For example, a 24-fiber: Blue tube 01-12 = G.652 and
What the guys often do locally in the Metroβs, is to install hybrid cables. For example, a 24-fiber: Blue tube 01-12 = G.652 and
Orange tube 13-24 = G.655, etc.
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