A little inside information by an Employee.

[Escapee]

Originally Posted by gadge

sorry to but in bit of topic is it true tvdrive has been delayed? seems to be a bit up in the air at the moment.

I had to google that to find out what it was.

Perhaps someone working for tw/ntl will know a bit more.

[Virgin Mary]

Originally Posted by Escapee

I doubt if the bandwidth would be available, I know they used to run comms over the rails but I'm not really that clued up on it. Many years ago I knew a guy working on comms for BR, I think the technology then was a LF or HF signal. I also remember seeing some of this old equipment available at a radio rally aroundb that time. (thats how the discussion started)

It was a long time ago so perhaps I am confused and they were for use on overhead electrics. Any for of communication down the rails will be a problem, you have to consider loosing connections at points, and corrosion if not on a continuous welded section of track.

Also remember that the signal levels would need to be very high if using LF/HF in the same manner as ADSL, because the railway lines are not twisted pair With twisted pair the crossing of the wires cancels out any unbalanced signal. ie: interference picked up on the line by using the push-push effect. (I'm sure you could Google for an explanation)

BT's lines were designed for audio signals, getting good balance at HF frequencies (that ADSL uses) is not an easy task. The old Rediffusion HF cable TV systems used balanced twisted pairs desugned for the job, but they still had problems with balance and interference.
The use of digital technology these days goes some way to mask the inherent problem of using twisted pairs for broadband communications. Twisted pair in itself is not a bad thing, it has a higher velocity ratio than coax, and has less loss/km. The real problem is maintaining good balance at all the joints, the use of chock block type connections ruins the balance.
Whilst a network can be efficiently maintained for audio or low speed data (voice) using it for broadband is far different. ADSL technology masks the problems with error correction, so its very much like trying to make a silk purse out of a sows ear.

Using the railway lines would only offer one ADSL line shared between all the users on that track, even if it did work satisfactory.

Many thanks Escapee.

I have noticed that the rails are no longer disjointed, they put a thick wire and connect disjointed lines/pints on the side, no idea why.

Why can't they apply the short-wave idea used on the powerlines?

[Escapee]

Originally Posted by Lobster Ring

Many thanks Escapee.

I have noticed that the rails are no longer disjointed, they put a thick wire and connect disjointed lines/pints on the side, no idea why.

Why can't they apply the short-wave idea used on the powerlines?

I guess they could, but I think it would be limited bandwidth.

I think the comms they used on the rails long ago was just audio for communicating with the train drivers, this was multiplexed upto a higher frequency possibly to get extra channels and also to put it outside the human hearing range.

I'm not sure how their automatic signal system works, perhaps someone may know if its done via RF telemetry or some other method?

I'm not sure how they got around the fundamental problem of wooden sleepers being good insulators in the hot summer months, and fairly good conductors in the wet months. I couldn't see the system working for anything more than carrying audio or low speed data. I dont know how much of the rail network is now continuously welded rail ie: no joints, fish plates etc. But some of that used to use concrete sleepers, all this low frequency stuff below the HF band is not really an area I have ever got involved with. Putting LF/HF signals down the mains and relying on transformers and some capacitors to offer a high resistance to 50Hz is something I dont go near.

I would say putting LF/HF etc down a railway line wouldn't work, but apparently it does. I guess it was a matter of using what was available as a cheap implementation for communications, just the same as ADSL is.

PS: I wonder how they managed with comms when a train was on the line, ie: shorting the two lines together via the axle. I guess it could work because the frequency used wouldn't see it as a short unlike 50Hz or DC.

[Richy99]

Originally Posted by zinglebarb

so whats the timescale on this 21C? I knew this was on the cards but this is gonna take ages surely?

and looks like cardiff will be one of the first ones to get it, july 2007 for my local exchange

[jaypeemac76]

Originally Posted by murfitUK

What's the point in boasting about having cables capable of 100MB/s when my 4Meg service won't go above dial-up speed for 8 or 9 hours each day?

And BT's claim of 8MB being applicable to 7% of the UK... isn't ntl making similar false claims by advertising UPTO 4Meg when the network is obviously not capable of delivering. Might as well advertise a service upto 1 billion trillion gazillion MB/s and then when the complaints come in say "Ah, we didn't promise you would get that speed, we said upto..." which is the reason ntl complained about another service provider's adverts. Pot & kettle?

I've got the samew problem mate, except i'm supposed to be on 10 meg bb

[Stuart]

Originally Posted by gadge

sorry to but in bit of topic is it true tvdrive has been delayed? seems to be a bit up in the air at the moment.

That is very off topic, and we have a thread dedicated to that (and indeed, a forum dedicated to the TV drive). Look at http://www.cableforum.co.uk/board/sh...php?t=33604693

[Elrond24]

Originally Posted by Escapee

I guess they could, but I think it would be limited bandwidth.

I'm not sure how their automatic signal system works, perhaps someone may know if its done via RF telemetry or some other method?


PS: I wonder how they managed with comms when a train was on the line, ie: shorting the two lines together via the axle. I guess it could work because the frequency used wouldn't see it as a short unlike 50Hz or DC.

Hi thought I'd butt'in I am not an S&T Engineer but can say the railway is bad environment any comms no matter how sophisticated.

My experience lies in Power Transmission, but the basis of signal telecommunication is that on Overhead Power Tranmission DC signaling is used and on DC Transmission AC signaling.

Bad - in that our rectifier,s induce 300 hz into all adjacent copper cable's, our HT cable surges (be it for our network or the REC), induce upward of 1,500v, mother nature via Lightning strikes at or close to running rails destroy most front ends, TOC induce further interference via chopper ccts in their trains, every night especialy in the London area track ccts(running rails) are disturbed due to engineering. I will not go on !!

The greatest disapointment that Network Rail cannot extend their existing Fibre optic system nationwide for commerial use.

[Escapee]

Originally Posted by Elrond24

Hi thought I'd butt'in I am not an S&T Engineer but can say the railway is bad environment any comms no matter how sophisticated.

My experience lies in Power Transmission, but the basis of signal telecommunication is that on Overhead Power Tranmission DC signaling is used and on DC Transmission AC signaling.

Bad - in that our rectifier,s induce 300 hz into all adjacent copper cable's, our HT cable surges (be it for our network or the REC), induce upward of 1,500v, mother nature via Lightning strikes at or close to running rails destroy most front ends, TOC induce further interference via chopper ccts in their trains, every night especialy in the London area track ccts(running rails) are disturbed due to engineering. I will not go on !!

The greatest disapointment that Network Rail cannot extend their existing Fibre optic system nationwide for commerial use.

So the signaling data is at 300Hz?

I remember many years ago that ntl actually came to an agreement with Network Rail or whoever it was at the time, to use the railway fibre/comms ducts in the South Wales valley's. As far as I'm aware they never actually made anything of this agreement, dont quote me but I think the agreement involved ntl using the ducts to run or upgrade the existing fibre routes and offer dark fibres for Network Rail to use. I dont remember the exact details, but had the information at the time from someone involved in the discussion.

The deal was struck (if it was ever signed) at a time when ntl in South Wales were called ntl but were in fact CableTel, It was around the period that CableTel bought ntl but before they bought any of the CWC/Comcasts/Diamond mob etc.

If they had never gone out and bought these companies we would probably of still seen the same end result, ie. One cable company. I do believe though we would of seen more areas, especially profitable ones serviced with cable.
I believe that CableTel/ntl buying up most of the opposition early on had a big impact on the overall availability of cable in the UK.

[Elrond24]

Originally Posted by Escapee

So the signaling data is at 300Hz?

I remember many years ago that ntl actually came to an agreement with Network Rail or whoever it was at the time, to use the railway fibre/comms ducts in the South Wales valley's. As far as I'm aware they never actually made anything of this agreement, dont quote me but I think the agreement involved ntl using the ducts to run or upgrade the existing fibre routes and offer dark fibres for Network Rail to use. I dont remember the exact details, but had the information at the time from someone involved in the discussion.

The deal was struck (if it was ever signed) at a time when ntl in South Wales were called ntl but were in fact CableTel, It was around the period that CableTel bought ntl but before they bought any of the CWC/Comcasts/Diamond mob etc.

I believe that CableTel/ntl buying up most of the opposition early on had a big impact on the overall availability of cable in the UK.

As I say I'm into Power Tx, Wessex Southern, DC 750v, 3rd rail.
Our S/stn are every 3 miles our rect. put our 300Hz, S&T use various Freq.
It was an small example of the the unfriendly electronic environment.

Deal must have been in the Railtrack days, kept being told against our licence to sell cable space, but diversity of routes with a massive handling capability (overground)must have be a money maker, if we still had a in-house IT group.

It been a good xmas, no bodies/fatalities, odd car turning left on X-ing, and no tripping so far this shift .

[clavox11]

As for the prices, NTL.Telewest give you free Line Rental (with CableTV packages), Free Weekend Calls to all Local & National UK home telephones - Our call package prices are dropping, we are the first company in Europe to offer "Quad-Play" - visit the websites, compare the prices, and you will see, NTL.Telewest works out cheaper, and you will be able to get it all on the one bill, so it's convenient too.
But why should I take on ANY wired phone service when I can have in some cases free line rental and in others pay the measly sum of 1.99 a month and have free calls every week day night and all weeked using VOIP.
Secondly I feel that I for one (and there are many other customers )cannot now beleive a single word any member of BY staff says anymore ,when one high ranking staff member was asked by a customer if there was any plans to impose capping,throttling,traffic shaping,call it what you will on customers and the aswer was a definite NO and two days after this it was announced that TRAFFIC SHAPING ( robbing customes of bandwidth they had paid for )was taking place in the Northwest of England.
I am on a 4Mb connection and for the last two months my speed has dropped from around 480Kb/sec to less than 200Kb/sec EVERY DAY and I hardly download anything .
It isn't the loss of speed that is bothering me it is the fact that I am paying for a 4Mb UNLIMITED service and only getting less than half of that for around 8 hours pr day .Yes I know that speed can drop due to network congestion and other matters compleatly out of TWNTL's control and this is covered in the T&C's but the delibrate curtailing of a customers speed by the company isn't .

[etccarmageddon]

NTL charge £11 for phone line rental - it isn't free.