I have a 18 km link of single mode pirelli fibre. over the last 6 > months I
> have lost approx 3 dbm over the length. I am running a harmonic
> lightwave
> laser with diital transport streams.
> While testing the link with an OTDR the trace shows a lot more
> attenuation
> than 4 years ago. It used to be on average 0.45 db/km but now its > 0.65.
> The trace shows a normal launch but a steeper slope ( more
> attenuation) and
> a very noisy trace even when done from both ends as though there were a
> laser souce on the opposite end to my OTDR. I checked the splice joints > and
> they were waterlogged possibly from day one.
> The local expert said that the fibre is porous and will absorb water, > or
> any polutants in the water washed in off the road could have a
> chemical
> reaction with the fibre and change its chemical structure. he also said > that
> as the cladding may have deteriorated then licght from an adjacent > fibre in
> the same tube would crossover to my fibre.
> is any of it true as he has recommended replacing the entire 18 km
> Abraham
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