Fibre optic LNBs the future?

Robbo

Try 200m.

rolfw

Thanks, will be interesting to hear from someone regarding an actual installation.

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richard_s

you can find morehere
_http://www.globalinvacom.com/products/pdfs/FIBREarticleGI.pdf

richard

mkgigs

ive seen the system work a few months ago and yes it works well.You will still have the same problems tho as it converts the feed back into coax.
The idea isnt new really been around for years.Think about it cable run a fibre back bone around the uk sending TV teleco and broadband then convert into copper.Most the faults end up from poor cooper installation tho.
Now people know why i spent time working for cable lol...wanted to see how the network worked.
If global expand on this system no reason why it cant be used to distrubite the broadband in flats etc that the goverment are so eager to give to people. Cable modems work through the coax 1st than back to the local node wud need multi switches with a return path to pass back to the headend unit.End users cud use a modem same as for cable tx at about 25 to 30 mhz for return.

kenny1234

I think it'll def be the way forward, even more so as price should eventually drop- would be so nice to have no loss sat system at home

I also understand no earth bonding required in multiple output IRS systems using fibre optic.

Channel Hopper

There would be no need for satellite links at all if the fibre-optics are rolled out across the UK. One head-end and a system of funnelling switches at the end of the road.

There is a very fine line between "hobby" and "mental illness"

mkgigs

no earth bond of the headend is needed but yes will still be needed on the multiswitches as this is still copper property to property. Think we are still ages away on having a complete fibre system dont think sk....y will be investing in fibre stbs yet due to expense of design etc.
Cost of fibre lnbs etc will quickly drop in price once companys doing the infastructure take up the advantages of a fibre back bone system in buildings and new build estates.
Dont think sk...y will be backing this to much as it makes the system really into cable network and once the multiswitches are about for return path makes it a one fibre for tv teleco and broadband. IRS engineers will need re trainning into the system set up and workings. Ive found enuff evidence to show alot of them have enuff dealing with current IRS networks and service issues.

satelliteman

Yes subscriber feeds still need to be earthed.

satelliteman . ..... A Detailed DiSEqC Motor Installation Set Up Guide > HERE Quick Reference Guide also > HERE Satellites UK site Advertisers . An Installers Choice ...... Follow us on .

rolfw

Don't think Sky carries any relevance on this, they certainly wouldn't use it for standard residential installations and are only interested in what is delivered to the subscriber outlet in IRS systems, most of which will be coax fed on the final leg. Obviously longer term the way to go will be for total fibre infrastructure in IRS systems, but that's another story.

For the purposes of this thread, we are interested in The quality and performance of the LNB and ancillary kit, plus the price compared to a more traditional coax fed system.

I've calculated that ignoring the need for a larger dish size on a 50m run of WF125 five core cable, the fibre option works out slightly more expensive, but raise this to above 50m and the fibre system comes out cheaper, take off the difference in price due to the ability to use a smaller dish and the fibre system wins hands down.

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mkgigs

Of course the fibre feed wins both in performance and cost.Labour will be greatly reduced as well.Real time saved will be on 9-13-17 wire systems and the poor engineer wont have to haul loads of cable drums around always a problem when the lift is broke lol

Turok

hello i plan,to buy now this fibre lnb in flansch version,for my gregory dish from invacom the current price is 200 €
where i can buy around 30 meter fibre optic cable,and how much this would coasts?
how this lnb and the cables are conected?

Robbo

You could try one of the site sponsors, I believe southernsatellite was selling the Fibre optic gear.

DishDick

Hello
I don´t think people here have really thought about this new technology as it stands. I think it is deeply flawed and inefficient.

I will give you an example. Say you wish to distribute a satellite signal to a small estate. Lets use 32 houses as that is what Global/Invacom say is the maximum number of outputs possible from their LNB - so the last outputs on that system (assuming the splitters have no internal loss – impossible but we shall assume for ease) will have 3.125% of the signal coming out of the new LNB. Assume houses in a row and dish at beginning.

With say a televes modular cascading multiswitch system, you would run four cables out of quattrol lnb to first house fit a four output multiswitch, you would then run four cables from that multiswitch to the next house where there would be another multiswitch and so on and so forth to house 32. (OK so I have ingnored amps – keeping simple as I am trying to show cable usage).

On the new system, yes one feed comes out of LNB to house one. Now we need to work out the most efficient way to split the signal. If we try to minimise fibre usage by using a two way splitter feeding one output to the new fibre to coaxial converter (I will abbreviate FCC) and the other output to house two and repeat this we will reach 3.125% of original signal by house five . No good.

To get 32 outputs we have to split the feed at house one with a two way splitter, one cable continues its run, the other one is split with a four way splitter, three of these feeds continue their run, the remaining feed is split by another four way splitter. Three of these feeds (sub Sub Sub feed) continue their run and the remaining feed goes to a four way FCC. So now we have 1 + 3 + 3 i.e. seven cables continuing to house two. One of the sub sub sub feeds goes to a four way FCC, then the six remaining cables go to house three, again one sub sub sub feed goes to a four way FCC five feeds go to house four, this continues until the first set of sub sub sub feeds are used then a sub sub feed will need to be connected to a four way splitter and so on and so forth.
Now these FCC are about three times the price of a standard Televes cascading modular multiswitch, and the LNB is at least three times the price of a standard quattro LNB. Now think of the cost of these fibre optic cables (pre-terminated is expensive). Ok so there is little signal loss with fibre and you save a little on amps. I can only think this system would be cost effective if you had a circular estate with the dish in the middle and used and eight way initial splitter. A spiders web kind of design.

I think the system would have worked if they had a daisy chainable system. Had a laser amplifier in each FCC (so negligible signal loss) and just run another thin cable for low voltage power for the amp ( I take credit for this idea and am happy to accept royalty cheques!!) So only two cables power and signal.

Pity I had been looking forward to fitting a fibre optic system, but after working out the practicalities (or otherwise) of the system it is not cost effective or time effective.

Thoughts anyone?

satelliteman

The obvious design advantage is very little attenuation over an extremely long trunk.

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Channel Hopper

There is no real reason why the fibre-optic system cannot have a parallel output, with all four outputs of the LNB combined at the head end and then driven simultaneously down one piece of cable.

Switching can be done at the remote end via a simple optical changer, not unlike the old downconverter/upconverter BSB systems mentioned in the Technology section.

There is a very fine line between "hobby" and "mental illness"

DishDick

Hi

Satelliteman I did say"Ok so there is little signal loss with fibre and you save a little on amps." but what I was saying is that you are using much more lenghts of fibre than with coax. With coax the max number of parallel cables between multi switches is 4, there is up to 7 with fibre, and its not cheap when bought pre-terminated.

Channel Hopper, all four outputs of the LNB are combined and sent down the fibre. The problem comes when you splt the signal. If you want one cable to run down the estate and you split into two the max signal you get is 50% out of each , so if you feed one fibre to coax converter from the first split it has 50% of signal, 50% goes to next output, but if you split again into 2, 25% of the original signal goes to the fibre to coax converter and 25% towards next converter ie (based on % of original LNB strenght)

100%

1st split 50% to Converter, 50% towards next house (which will have to be split again)

2nd split 25% to Converter, 25% towards next house

3rd Split 12.5% to Converter, 12.5% towards next house

4th split 6.35% to Converter, 6.25% towards next house

5th split 3.125% to Converter, 3.125% towards next house

6th split - signal too low.

Then the way I said

100%

First split 2 way 50% each


One feed left is left unsplit so 50% output, the other is split into 4, 12.5% to each, and each of those split into 4, 3.125% each. One 3.124% output feeds one converter, seven feeds totalling 96.875% go toward house two.

Second house, one feed 3.125% goes to converter six feeds totalling 93.75% go towards house three. you can see even at this point over 70% more signal is going to house three using this method than the single cable (but using six cables not one). These fibre to coax converters do not have a through put and have to fed directly from splitters. Look at the Global/Invacom PDF.

Thats the problem, If the signal converters had a throughput with minimal loss (due to built in amplification, yes we could have one fibre going from house to house.

Channel Hopper

Then the most common failure would be that any problem (accidental disconnection for example) in one property would mean a loss for many others.


The coax would be at the remote end, it is the multiple connections at the head end - either using an active fibre splitter or having an optical LNB with multiple fibre outputs (an octo for example, each output carrying the full signal) - that would be the most convenient device to use in such a system.

There is a very fine line between "hobby" and "mental illness"

DishDick

Hi Channel Hopper,

"Then the most common failure would be that any problem (accidental disconnection for example) in one property would mean a loss for many others."

I have been involved with two very large systems using this method and ther has never been any problem like this. Due to the distances involved and the duplication caused by the way the fibre system is designed to replace one system with fibre will cost @ one thousand five hundred pounds more than if we could loop through. And the same again extra for the proposed expansion. Three thousand extra pounds worth of fibre optic. Thats on top of 2.5K for the converters ect for existing set up and 2.5 - 3k for proposed larger set up i.e total cost - direct material only 8 thousand 500 pounds. Bugger that - keep coax system!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!

Channel Hopper

You are talking initial costs of replacement though.

If you ripped out the cable, the copper could be sold, reducing the initial outlay.

Unless we are talking at crossed purposes of course.

There is a very fine line between "hobby" and "mental illness"

rolfw

I guess that there are always going to be exceptions to any rule and it may be that linear developments of houses as you have outlined above require different solutions.

Having said that, the vast number of installations (certainly in the UK) will not be of that type and the fibre solution will save both time and money.

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PaulR

It's horses for courses isn't it?

The good thing is that there is a viable alternative that is better in a few situations. The fact that it doesn't suit every application doesn't means it's no good at all and should be wiped from existance any more than the traditional way has had it and should die away completely!

PaulR As I get older I find myself thinking about the hereafter - I go into a room and then wonder what I'm here after.

DishDick

A few replies -

Channel Hopper, yes we are talking about initial costs 8.5k of them (not incluing any labour or making good costs). Alot of money to anyone. And I don´t think any money got from scrap copper would make much of a dent, if lucky a couple of hundred pounds.

rolfw, it doesnt have to be linear houses. Think of a block of flats, its exactly the same. Lots of extra cable usage (fibre) over a cascading system.

PaulR - Not very impressed with your response. Thought this was a discussion forum. Question posed by thread was "Fibre optic LNBs the Future?" Now I stated my viewpoint and gave examples to explain and justify that view point. I also gave a possible solution to the problems I foresaw. Can you give me a detailed example where in a large building or complex fibre is cheaper or easier to fit?

Topper

No you are wrong it is a self help forum for satellite enthusiasts/hobbyists, not a soapbox platform for someone who want to ram their opinions down other people's throats. You need to respect other members and their opinions. As it happens I agree with PaulR's opinion and it is horses for courses. All installations are different and some installations require expensive equipment to ensure they operate efficiently and effectively. Nobody on here has to provide such justifications to you especially members of the moderating staff

As it happens PaulR's post was in defence of fibre equipment stating that it is good there is a viable alternative so why the attitude?

War does not determine who is right, it determines who is left!

Formerly toppervte33h
whose six pack has turned into a keg

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DishDick

Forum is defined as "a public meeting or assembly for open discussion". And for clarity discussion is defined as " an extended communication (often interactive) dealing with some particular topic ".

Now then I don´t think I have rammed my opinions down other peoples throats as you put it. I thought logically about this system as I was very keen to buy one. But having mapped out the system, I saw what I thought to be a flaw and gave my reasoning. If you look at my first post I asked for any thoughts, incase I had made a mistake or there was a suitable work around. PaulR didn´t appear happy at me knocking a new system but did not give me any kind of counter argument (I use argument in the non-agressive form). It would be nce as part of an adult discussion if people would explain their points of view, moderator or not.

rolfw

I've thought about a block of flats, as have the designers of the system, I've also costed single and linked blocks of flats, not only can it be less expensive, but also means a smaller dish can be used, or perhaps remove the need for an IF amp.

You appear to be assuming a fibre only system, but in real terms this will at present not be the case and as time passes, splitters and taps will I'm sure be developed to cater for all permutations enabling fibre only systems with great savings in cable and labour.

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