atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Telecom Service & Providers How does this work? (Fiber to copper 101)

OK,

So the AT&T rep sold me on their U-verse service last night. It won't be a huge change for me, other than I can finally get rid of the dish mounted on my deck (local cable is Comcast, a company I really, really don't like, aside from the fact that in my experience, satellite TV is more reliable than cable) so I went with Dish network). Aynway I'll get 4 TV streams, 1 in HD. Could have gotten VoIP, but I have to, and want to, stay with POTS. Internet bandwidth stays the same (6 MB).

Price is about the same as what I'm paying now.

What I don't understand was I remember years ago being told about the upper limit of copper to transmit data. Of couse, this was in the heady days of 28.8 modems, but I clearly remember when the 56K modems came out, being told there was no possible way things could be made to go any faster; that copper had an inherent limit, and 56.6K was about it.

Of course, I've been getting POTS and DSL over copper for years now, but it wasn't until last night that I thought about this.

I can see that the technology on either side of the copper has increased tremendously, but I still don't quite understand how they are now squeezing so much out of the copper. The total length of the run can't be more than 1/2 mile give or take, from my demarc to the telco box in the backyard, and then from there up the street a bit to a piece of equipment they put in when they surrounded my subdivision with fiber.

One other question: Does anyone see a day when they finally bite the bullet and start running fiber to the home? The rep said it's getting to be standard practice in new subdivisions, but they aren't doing it in existing subdivisions because people don't want their yards torn up - I don't buy that argument; they went through it once (albeit many years ago) with POTS, and then again with cable. Is it really just a question of cost, as at the present day people really don't _need_ fiber to the home (I can see that changing in 5 years or so), and so the demand isn't there to cover the costs?

Sorry if this is a question that could be answered via google, just wanted to get your guys input on it.

Thanks
Matt

Verizon is already doing this with their FIOS servive and making a very big push. They are providing voice, internet , and TV on a Fiber ran to your home.

Matt,
The huge increase in bandwidth capacity for Telco copper is simply a reformatted all digital signal.

Going back to dial-up modems over POTS isn’t even really a fair comparison to what is going on with technologies like ADSL, Data or video service. Dial-up uses the Telco network in the same exact manner that a POTS voice call does. As in a modem call goes though the same call set-up process and uses PSTN (public switched telephone network.) The traffic that a modem call is transmitting and receiving may be representing the 1’s and 0’s that make up a digital signal that the two computers uses, BUT it’s formatted in an analog format between modems so it can use the POTS network.

For the world of DDS (digital data service,) ADSL, HDSL (a T1 technology,) ISDN and video (like you’re asking about) for one does not have to be compressed to fit into the PSTN. All these and more are terminated to specialized pieces of equipment that are set-up for the digital signal.

Next, the concept of HOW the signals are formatted down the pipe (copper) have been greatly improved. Telco equipment manufactures have discovered so incredibly slick ways to get more “bang for the buck” so to speak out of the copper, with each of digital pulses, by transmitting both multiple binary digits within a single pulse but also adding quaternary values within just one pulse.

Another thing that has allowed “bandwidth hogs” like Ethernet and/or video to be transmitted over Telco copper is by using IMA (inverse multiplexing.)… Even with applying the slick tricks of restructuring the digital signal, the capacity of ONE pair of copper is maxed out… By using IMA the signal can be broken a part to be transmitted down multiple copper pairs and then reassembled as one whole signal.

My opinion on will Telco’s start running fiber to all existing homes? … Someday yeah in the far off distant future, copper WILL go away… I’d compare it to “knob and tube” electrical wiring…. Today, there’s still very little “knob and tube” wiring out there and it doesn’t get repaired, only replaced. There is SOME truth to people not wanting their yards, drives, streets torn up for the placing of fiber… but what it really comes down to is MONEY! Outside Plant construction is expensive no matter what media is being deployed. As long as more and more bandwidth is being squeezed out of copper and IT WORKS, why bother with it ya know?

Bryan, Anthony -

Excellent - I understand now (well, at the 5000 foot level anyway!) - thanks much for the responses!

As a somewhat off-topic aside, I really feel sorry for Bill Esrey. I think if you look for the definition of "flop", it says: See ION.

But this is exactly what he wanted to do with ION. He got crucified for being 8 years ahead of his time.

But with Sprint now trading below $10 (it was over $50 under his watch).... it looks like he's getting the last laugh. Although I'm sure it tears him up to see what he built up being driven into the ground.

- Matt

Matt -

Welcome back.

I think 56K is still the high end for Analog Data service. But that's got to be able to handle the whole spectrum of Telco outside plant (load coils, bridge taps, repeaters, long distances etc.

You can get higher speeds if you clean the cable up, remove the load coils, repeaters and taps and reduce the distance.

The rule is - the more frequencies (bandwidth, channels, dial tones, etc) you want to put on a copper circuit - the shorter the distance. Increase the number of frequencies - shorten the distance.

With microwave running at 2GHZ we could go 40 miles. At 38GHZ only 1 or 2 miles.

Sam

A great example of the inverse multiplexing that Bryan was mentioning is how we deploy a standard 384KB ISDN BRI Video Conference circuit divided evenly across three separate copper pairs (128KB BRI per pair, then bonded back together to 384KB at the customer's NT1 interface) to utilize existing copper. Just like Bryan mentioned, it fully supports the customer's needs just fine!

Standard computer modem do not necessarily have to have higher base speeds to acheive a higher bit rate. Before the internet and PC/modem craze, telco only ever certified lines to 4800 baud, twice as fast as the fastest commercially available modem. When we hit 9600, 14,400, 28,800, and finally 56K, it was not a higher base speed, it is multiple channels of 2400 baud. Four channels of 2400 got us to an effective bit rate of 9600, etc etc (you do the math)

There are many limits imposed on analog signal, as we have all experienced, and modems are about the biggest hog we can put on the wire. Modems are full time bi-directional communicators, when connected.

Verizon, actually an electrical sub, is currently running fiber duct underground throughout my development. I am on a corner, so I got a christy box set out by the street, and some torn up areas of grass. I am curious how long it takes them to actually pull in the fiber, terminate, and get drops to the houses, more torn up lawns.

As an aside on this old post, I have also heard rumors from people back as far as the NyNeX time frame of the mid 90's about running fiber to the pod and doing copper over the short haul distance to the home. I know that NyNex had a proof of concept setup south of Syracuse, but I lost track of how it was going when BA took over and my contact took early retirement.

Another thing about POTS modems is that the signal as Sam mentioned is in-band, where as DSL uses the full spectrum capability of the wire. The Filter that they have you put on notches out the analog voice band so you don't hear it on the phones in the location. the filter also prevents noise from the phone end from getting into that out of band area that DSL uses.

When I was with GTE they installed two testbeds - one in Ohio and one if Florida.

They ran fiber to the curb (or backyard) and then ran DS-3s on two coaxes to each house.

You got 45mbs of bandwidth for phone, internet and TV.

The only problem they ran into was when they shut down the test, everyone freaked out when they did the disco.


Sam