In reply to a post by WWWombat:

A box on the telegraph pole, to one on the house? Without cable? Sounds like wireless. RF rather than IR.

You can use IR on a fibre cable, IR is still a light source, I read some place that you can get 1Gbps over Infrared, so its possible but unlikely.

I am assuming the OP was referring to the new connectorized boxes for FTTP/H, but I thought that they was only at the pole end and not at the home end.

Paul

I thought that the frequencies used on fibre were visible, so checked ... and they turn out to be infrared as standard. The eyes cope with spectrum between 400nm (blue) and 700nm (red). Fibre tends to carry signals at around 850nm, 1300nm and 1550nm.
http://www.thefoa.org/tech/wavelength.htm

However, @creakycopperline seemed to be describing something without a cable, rather than a relatively unknown factoid about fibre.

In reply to a post by WWWombat:

I thought that the frequencies used on fibre were visible, so checked ... and they turn out to be infrared as standard. The eyes cope with spectrum between 400nm (blue) and 700nm (red). Fibre tends to carry signals at around 850nm, 1300nm and 1550nm.
http://www.thefoa.org/tech/wavelength.htm

However, @creakycopperline seemed to be describing something without a cable, rather than a relatively unknown factoid about fibre.

The emitters used on fibre are visible, I was just referring you can use IR Transceivers over fibre cable.

A team including myself 25 or so years back used ADCS and DACS along with some multiplexers and sent 16 channels, 8 consisting of audio, 7 digital data channels and 1 control channel.

And we unrolled a few reels of thick fibre cables (the cheap stuff that didn't like bends LOL), spliced (pair of cutters, eye piece, fine sand paper and washing up liquid LOL, oh the good old days) the ends and joint them together into one huge long fibre cable and we sent the 16 channels from one side of the campus to the other.

It worked rather well we thought, mind you we had to slightly over drive the IR Emitters a little due to the length of the fibre cable.

So we don't need to be able to see the light for it to work, all that needs to see it is the IR Detectors.

That's what I was getting at.

My impression that I got from the OP was it might be using the new connectorized blocks, there was no mention of wireless or using fibre cables, but they did mention IR which led to my reply.

But yeah, without the full information we are all just guessing LOL.

Paul

The singlemode fibres we use for our vehicles at work (subsea ROVs) use between 1470 and 1610nm wavelengths which I believe are in the IR range, generally coming from an 8 channel CWDM at each end so we can have several things talking on the same fibre.

AFAIK we always used 850nm sources on any multimode fibres that used to be used but e have since moved away form them to get better distance and attenuation.

I have always assumed OR would be using something more fancy like DWDMs or similar to get a shedload more channels down the same type of fibre...though that is a TOTAL guess, doesnt really make any odds to me what is used as there is next to naff-all chance of fibre showing up where I live in the near future

I saw that older stuff was nearer 850nm, which I guess is approaching visible red.

BT do use WDM, but I think it has so far been more associated with the core and backhaul fibre, rather than the access network.

In the access network, BT currently use bi-directional GPON which I think is 1310nm and 1490nm, providing 2.5Gbps down.

They have shown demos of multiplexing 10Mbps XGPON and 40Mbps NGPON2 onto the same PON. XGPON uses a different pair of wavelengths. NGPON2, I believe, employs a DWDM set of wavelengths in the 1500-1600nm region.

I think we'll start seeing XGPON in use over the next couple of years, as Openreach start offering gigabit PON services to businesses.NGPON2 will be further off ... but if Openreach start offering gigabit symmetric, then they'll probably have started to use it.

Yes. Sounds probably as if the engineer had seen FTTrN like this, and got excited about it being deployed everywhere whilst not knowing the bigger picture, doesn't it?

FTTrN has been active in places for at least a year and a bit now, it's just (relatively) rare.

Edited by deleted (Sun 15-Jan-17 20:12:53)