OT - BT testing 800Mbps broadband

[Dave Liquorice]

That is variable depending on if you have to dig to install. BT have ducts all over the place so pulling in a new blown fibre tube is not a big deal. I expect the actual costs of fibre, even with the two stage installation will be lower due to the cost of copper. And a "blown fibre tube" isn't neccessarly something akin to a large drinking straw.

They've just pulled in a blown fibre tube here that is very similar to 1" black alkathene pipe with about a 3/4" ID. I hope to catch 'em in the act of blowing the fibre but unless I happen to be passing one of the 2 km points at the right moment I'll miss it.

Other installs of blown fibre have been bright orange "shotgun" stuff cable clipped to walls etc. but I suspect that is the run from the nearest fibre node to the final position. BT boxes generally have 1/2 to 3/4" white tubes comeing up out of ducting

[jrwalliker]

I watched a BT fibre install. There is an adapter box near where the fibre enters the building where the transition is made between black underground tube and the white shotgun tube inside the building. Underground in the nearest manhole there is another transition to the large multi-tube that is used for long runs. This has a ground conductor which has continuity all the way to the exhange which is used for tracing from the surface. The whole underground system is permanently pressurised.

When the fibre* is blown, one operator drives the compressor end and the other sits in the office until suddenly many metres of fibre land on the floor before the feed gets shut off.

One of the fibres is then fusion spliced to an LC tail which plugs into the optical transceiver which is a dual wavelength duplex device.

• Its actually four fibres bundled together. The ends are held together wi th a ferrule which looks a bit like a hollow airgin pellet. There is no pl astic jacket on the fibres, just a coating of slippery glass (probably) bea ds which maybe improve the viscous drag as well as smoothing the passage of the fibre.

I have the first few metres of this fibre as a trophy.

John

[Andy Burns]

Or the other operator sits there saying "no, nothing yet" over the phone, until his colleague gives up, then the next day they send Murphy's to dig-up the car park to find where it all went ...

Yes, it is nowadays, a few years back they were half duplex.

[Dave Liquorice]

Nothing new there lead sheathed and paper insulated cables where also presurised to keep the damp out. Same reason for fibre, the relatively unprotected fibres you saw blown dosn't like damp either.

The fibre itself is very fine, most of what you are handling is a plastic jacket... BTW be careful handling the ends if the fibre itself. If it gets out of the containing jacket it can work it's way into you and being transparent and tiny be a PITF... Did the fibre jointer not have "sharps" bin for the offcuts?

[dennis]

Have you seen it when the get the wrong tube and some unsuspecting person get a couple of km of fibre in their basement?

[The Other Mike]

Surely simplex?

[jrwalliker]

Of course he did - I asked for a sample - and got it - togeher with dire warnings about the sharpness of the fibres.

John

[Dave Liquorice]

That shouldn't happen:

I'd expect unused tubes to be capped to keep wild life and/or water out.

It would be a bit obvious at the recieving end that there was no air coming put of the tube before they start trying to send anything through.

AIUI they blow through a soft plug first to clean/dry the inside and make sure there is more than just an air path.

[jrwalliker]

They certainly didn't do that the time I was watching.

John

[Yendor]

Yep, you should send a pellet first to confirm the correct tube and no blockages.

Also the tube should be capped with an Airstone to allow air out, but stops the fibre when it reaches the end. Then the Airstone is removed and a few metres is fed out slowly.