Plastic Fibre Optics

spongebob

I have recently become interested in this technology as it is apparently a lot easier to work with (and cheaper) than Glass Fibre optic which is what is used over long distances. I understand that it can support 1Gb over about 1km .

Has anyone in here used it or come across suppliers or costings or tutorials on the technology ? I'd be interested in hearing your tips and experiences. Unlike glass fibre which is a bitch to join and splice the plastic stuff is apparently almost as easy to work with as CAT V .

It is to do with a notion I have about village cable networks in Ireland .........

M

DMT

Modal dispersion losses are far greater in plastic fibre than in glass fibre. Convertional plastic fibre is step index in nature and has a low bandwidth making it unsuitable for long distance, high bandwidth usage, unlike singlemode or even graded index glass fibre. As such, it is unlikely to be suitable for a village cable system you suggest.

yellum

http://www.firecomms.com/

Talk to these Cork guys maybe ? They're nice people. Had dealings with them before.

Capt'n Midnight

What distances can it run at what speeds ?

I presume it would be good for 10Mb within a new housing estate..

Yes the losses are far higher - but then the distances and speeds are far lower, could use quartz for the junction boxes.

Are plastic cables more pullable ? if there was copper in a conduit already could you use it to pull through plastic ?

bminish

I am meeting a fibre Guy tomorrow evening and I can ask him about it.

I have used multitude plastic fibre for digital audio work it's easy to put plugs on (sharp razor blade and a pliers will do an ok job) however audio doesn't require very high bit rates by today's standards, sp/dif is only 150 KBs.

Singelmode glass probably has a better bend radius than multimode plasic and is a similar price per m, the costly bit of course is fitting the connectors

.Brendan

iwb

Right, time to dispel some of the myths of glass fibre optic cables.
First of all, in our modern world, there are 'quick connect' systems for multimode and singlemode fibre which are relatively low cost and a strand can be terminated in around two minutes.
The process gives you an ST, SC or other common connectors on the end of a fibre strand, ready to plug into a switch.
If you want to do fusion splicing of strands, you can rent a splicer by the day for around €300 and almost anyone could use it after an hours tuition on the unit.
A fusion splice is an amazingly good mating of glass. It is virtually invisible to the equipment and the splicer is practically automatic. Once you put in two very clean, well cleaved pieces of glass, you get a perfect splice a few seconds later.
Fibre optic cables are very resilient. Depending on the construction, they can have a recommended maximum pull for installation of 500lbs. Try to imagine lifting a fairly substantial motorbike, that is a lot of pull. Of course, care does need to be taken to tie the cable properly and so on. Bend radius also needs to be observed but again, the cable is very resilient.
50/125uM multimode has decent bandwidth but unfortunately, it isn't that future proof as it will run Gigabit only to 550Meters and 10Gbit far less than that.
Singlemode on the other hand is very future proof and can run terabits per second for miles. Unfortunately, the trade off is that the equipment costs more.
I haven't worked with plastic fibre but I do know that they hope to replace glass in some instances in future. I don't believe it is ready yet and I also don't think that it is the right solution for your problem Muck.
PM me if you want some more commercial information which I know I shouldn't post here.

spongebob

Thanks for the help guys. I was hoping to hear that fibre joining and termination was becoming less complicated and costly and sure enough that appears to be the consensus.

The 'housing estate' model is kinda what I had in mind Cap'n , if the joining and termination is relatively straightforward then there is no reason why a competent local group cannot install these systems themselves.

A key advantage of fibre (glass or plastic) in Ireland is its resilience in the face of drizzle and rain .....as against copper. It could go down drains for example . It may easily survive being pushed along gullies by sewer rod assemblies .

I will post some more general info once I follow a link or two and work out the logistics per metre and per join / termination

M

rardagh

Hi Muck,

I think you have a very good idea with this. Some issues I think need to be examined more about this include:

1. How do you run this from house to house? Direct buried, Overhead; using blown or standard tubing?
2. My guess is that it appears that the best topology is a star topology, with 10/100 connections to the premises and gige backbone to the interconnect point, what do you think?
3. For single mode I think you are going to require fusion splicing, as in the previous post, you can use barrel joint for multi-mode fiber but for this application you should be using single mode.
4. Would the gov. allow a community group to buy fiber at the price they negotiated for the MANs under some sort of community draw down mechanism?

I like the idea a lot and have seen it successfully deployed in towns like wellington in New Zealand cost effectively. An interesting link is:

http://communityfiber.blogspot.com/

spongebob

Originally posted by rardagh
I think you have a very good idea with this. Some issues I think need to be examined more about this include:

1. How do you run this from house to house? Direct buried, Overhead; using blown or standard tubing?

A la Co-Ax cable I was thinking or simple tubular trunking (the round 1" white stuff) .

2. My guess is that it appears that the best topology is a star topology, with 10/100 connections to the premises and gige backbone to the interconnect point, what do you think?

Yes. A shared Docsis type topology may not be the best idea.

3. For single mode I think you are going to require fusion splicing, as in the previous post, you can use barrel joint for multi-mode fiber but for this application you should be using single mode.

This depends on cost and on ease of installation and maintenance ...which is why I started the thread.

4. Would the gov. allow a community group to buy fiber at the price they negotiated for the MANs under some sort of community draw down mechanism?

Lets hope we have a kinda workable model (like the Group Data Schemes) by the time the next tranche of Community funding is available in 2004

Thanks for the link.

M

iwb

I posted some time ago asking why we couldn't just do ethernet over Cat 6 to a group of houses and backhaul using fibre from there.
My main question was rights of way. Are permits necessary to run cable from house to house (like CATV does) or is it simply a question of getting permission from each home owner?
I foresaw a situation where Cat 6 would be run in both directions from a designated point (possibly someones house but it introduces difficulties) to about 85 meters to allow a few metres inside the last house. That way it would be very cheap to enable any one house, just using a bog standard RJ45 ethenet interface.
The aggregation device would be a relatively inexpensive switch with gigabit fibre uplink.
If fibre wasn't initially an option, FSO or wireless could be used in the interim. It would all be star topology and conform to standard network topology. Everyone would have the potential to communicate on the local network at Gigabit speeds and the cost would be a pittance compared to the rubbish estimates that are out there for 10Mbps to every home and so on.

BigEejit

I found this ages ago, it shows which fibre will do what ... depending on the number of nodes and how far from each other you might find that just buying patch cables would do the job (instead of renting equipment and buying fibre and connectors etc) ...

Capt'n Midnight

Where can you get reels of plastic fibre ?
RS do short lenghts - and almost everyone else is cheaper .

Water flows down hill. All houses have storm drains. They all flow in to the main drain. Not sure on the pipe diameters - but you might be able to roll/float a ball with fishing line on it ... what sort of non toxic sealant (thin cement ?) would you put down to hold the cable down and stop it snagging leaves and other junk in the drains.

Don't the existing copper cables run in conduit - I take it no chance to blow the fibe through them - though the other utilities might get upset.

yellum

This is slightly off-topic but what could be done to push councils to allow space for fibre in all new ducting in estates ?

I assume there are certain criteria that need to be met before you can build a house/housing estate. Are these criteria set locally or on a national level ?