cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
Highlighted
Contributor
311 Views
Message 11 of 31

Re: Jargon And The Real Picture

So the physical aspect of fibre optics line engineering is a simpler technology?  Light pulses down a tube, go or they don't go, it's the computing at the exchange end that requires specialisation?  For the majority of us the customer end hasn't changed...has it?  It's still copper wire...the 'modulator/de-modulator' still modulates and de-modulates.

 

This 'profiling' of the customer's line is really a control mechanism...it allows bt to eek out the bandwidth across the maximum number of customers by 'adjusting' what each customer gets, regardless of what they're paying for!!  Otherwise, why does the download speed vary over a period of days?  (accepting the daily 'busy period'...5pm - 10pm)

0 Ratings
Highlighted
Expert
293 Views
Message 12 of 31

Re: Jargon And The Real Picture

My speeds have never altered at any time of the day but on a cab that is near capacity this wouldn't surprise me because VDSL2 is massively susceptible to cross talk, the more connections in a cab the more it is effected and the bigger the variations when people are using it.

 

Profiling doesn't alter your speed to suit busy periods, profiling is set to keep your line at a set speed with the minimum of errors. Profiling is in place to keep your line stable and not to vary the speed and your profile wont change unless you have a massive amount of errors in a very short time which would destabilize your line.

0 Ratings
Highlighted
Contributor
280 Views
Message 13 of 31

Re: Jargon And The Real Picture

I'm confused then...I understood that a fibre optics cable is capable of carrying thousands of individual lines?  In the early days when fibre was first mentioned, the talk was of thousands of lines on a single cable...in fact 60k lines was quoted!  If that's anywhere near accurate a) why the problem with loading?  b) if there is an interference (crosstalk) problem with VDSL, it's been around a while, why no remedy?  These are simplistic questions...I know, but reasonable to ask.  If those of us who are interested (I was in networking with a high st name company, but a while ago) knew a bit more about how fibre works, we might be more understanding and patient.

0 Ratings
Highlighted
Moderator-Retired
271 Views
Message 14 of 31

Re: Jargon And The Real Picture

Maybe 60k telephone lines at a stretch, certainly not 60k broadband connections running at ~40Mb (not to mention upload) with plans to double this speed! 😛

Dean
BTCare Community Mod

If you like a post, or want to say thanks for a helpful answer, please click on the Ratings star on the left-hand side of the post.

If someone answers your question correctly please let other members know by clicking on ’Mark as Accepted Solution’.
0 Ratings
Highlighted
Contributor
264 Views
Message 15 of 31

Re: Jargon And The Real Picture

Ah...of course, I was forgetting!  Evenso, what is a FO cable's capacity in Bps?  Are there options on cable size or do they 'bundle' them?  How many run to a cabinet?  Given the physical nature and low capacity of copper lines, an old style cabinet can't contain many lines by comparison.  There was a lot of cable laying along the A4 several years ago...our cabinet is on the junction of our lane and the A4.  BT weren't laying FO cable that far back, were they?

0 Ratings
Highlighted
Expert
261 Views
Message 16 of 31

Re: Jargon And The Real Picture

A regular sized FTTC cab can carry 288 connection, the half sized ones carry 140 odd connections.

 

I'll be honest i do not understand the documents i have seen on crosstalk, it might as well be in french. I think it is to do with how high the frequencies are that are involved but an engineer would be the best person to ask.

0 Ratings
Highlighted
Moderator-Retired
258 Views
Message 17 of 31

Re: Jargon And The Real Picture


@tecmic wrote:

Ah...of course, I was forgetting!  Evenso, what is a FO cable's capacity in Bps?  Are there options on cable size or do they 'bundle' them?  How many run to a cabinet?  Given the physical nature and low capacity of copper lines, an old style cabinet can't contain many lines by comparison.  There was a lot of cable laying along the A4 several years ago...our cabinet is on the junction of our lane and the A4.  BT weren't laying FO cable that far back, were they?


TPON was a common technology in the 90s which could've been what the fibre cables were for. It played havoc when broadband was introduced mind you so has been done away with nearly everywhere.

 

Oh, and the capacity more or less depends on the signal frequencies/technology being used; bear in mind that CAT6 is only copper but can still handle 10Gb+ speeds via Ethernet.

Dean
BTCare Community Mod

If you like a post, or want to say thanks for a helpful answer, please click on the Ratings star on the left-hand side of the post.

If someone answers your question correctly please let other members know by clicking on ’Mark as Accepted Solution’.
0 Ratings
Highlighted
Contributor
248 Views
Message 18 of 31

Re: Jargon And The Real Picture


@DeanM wrote:

@tecmic wrote:

Ah...of course, I was forgetting!  Evenso, what is a FO cable's capacity in Bps?  Are there options on cable size or do they 'bundle' them?  How many run to a cabinet?  Given the physical nature and low capacity of copper lines, an old style cabinet can't contain many lines by comparison.  There was a lot of cable laying along the A4 several years ago...our cabinet is on the junction of our lane and the A4.  BT weren't laying FO cable that far back, were they?


TPON was a common technology in the 90s which could've been what the fibre cables were for. It played havoc when broadband was introduced mind you so has been done away with nearly everywhere.

 

Oh, and the capacity more or less depends on the signal frequencies/technology being used; bear in mind that CAT6 is only copper but can still handle 10Gb+ speeds via Ethernet.


I don't know what TPON is and I wasn't referring to cable laying that far back!  Maybe only 3-4 years ago.

 

Copper can handle 10Gb ?  You surely don't mean the pair to my house...what is CAT6?  Ethernet is not long distance comms, is it?  

0 Ratings
Highlighted
Aspiring Expert
243 Views
Message 19 of 31

Re: Jargon And The Real Picture

cat6 explained http://en.wikipedia.org/wiki/Category_6_cable  could be confusing to a layman. 

ethernet explained http://en.wikipedia.org/wiki/Ethernet  

---------------------------------------------------------------------------------------------
free your computer, use opensource
i'm a linux user & very happy about it
0 Ratings
Highlighted
Contributor
235 Views
Message 20 of 31

Re: Jargon And The Real Picture

Right!   So, as assumed, CAT6 is short distance (Ethernet) communications...10Gb = 180ft.  So we're still left with getting the signal from the cab to the house, which could be and usually is, hundreds of metres or more...back with a twisted pair?  If it's copper (mine was part aluminium but that's been replaced) it can support quite a few megs download!  I believe bt are going to offer 80meg download, later?

 

So, what can we expect, if we don't live next to an exchange or dont have access to a direct cable service...fibre to the house?  That won't be cheap!

0 Ratings