02-22-2014 1:43 PM
I have U-verse, TV, Internet and phones. This is all entering my home via a system of copper twisted pairs that was buried some 50 years ago when the area was first developed. Having some 60 years experience in communications electronics (retired electrical engineer) I am having some difficulty grasping how you guys fit all that stuff onto a pair of copper wires that were buried back in the day when 75 baud data was considered state of the art. Is there a book, or a place on the internet, that will provide some technical background on this? Specific data, not the type of stuff that Customer Service folks feed to the non-technical citizenry. Thank you.
(I asked this a week or so ago but never got a response...)
Solved by: Go to Solution.
02-22-2014 3:25 PM
U-verse is fiber optics.
This is my own over simplified non technical explanation. Others feel free to give a more technical explanation.
Depending on where you live it might be fiber optics all the way to where it enters your home (typically new construction) called FTTH or fiber-to-the-home) or more commonly the fiber optics part stops at your local VRAD and your TV/Intenet/Phone travels over copper wire the rest of the way in a loop to the VRAD, a video ready access device.
Unlike traditional all copper cable buried in the ground or on overhead wires, a TV connected to such a fiber optics network doesn't receive all your provider is sending "down the pipe" but waits till you select something on your STB then that signal goes to the VRAD and sends your requested channel along with 3 others back to you. Probably why right now why multiview is limited to just 4 channels.
The first link goes into some length how fiber optics works, the second is a short Youtube video that also explains it without getting to technical. I'm sure there's more detailed technical stuff on the web somewhere, perhaps somebody will share if they came across it. I haven't exactly been looking.
02-22-2014 4:14 PM
billy-xwow did a pretty good job of explaining, I'd just touch on a few points:
1) Fiber to the home is usually abbreviated FTTP (Fiber to the Premises), though I admit FTTH seems better.
2) Sending the fiber to a central device then distributing via copper is called FTTN (fiber to the node).
3) Because of the shorter runs, higher frequencies can be used than when the signal comes all the way from the Central Office.
4) However, just to confuse everyone, AT&T introduced a few years ago a new version of Internet service under the U-verse brand. It still usually comes from the CO (like old ADSL), can be (but rarely is) FTTN, but uses ADSL2+ (instead of the newer, higher bandwidth VDSL2 used in the original U-verse service). This service can be combined with voice, but never with TV. It can be deployed to subscribers a longer distance from the fiber endpoint.
02-22-2014 8:31 PM
02-23-2014 12:05 PM - edited 02-23-2014 12:10 PM
rchadwic - I could be wrong, but I think of the STB (Set Top Box) communicating with a server at some distant location. The connection through the RG (Residential Gateway) to the VRAD back to the server is a pipe, making no decisions/selections. The STB tells the server what channel to select. The server applies that channel to packets sent to the IP address of the STB. Any compression takes place at the server or upstream at the content provider.
You can look into the details of the type of signal used for this communication. And, there may be software to reuse common channels for efficient distribution. The communcation magic takes place at the IP level.
So, there are two answers to your number of channels question -
At&t can support as many channels as they create unique numbers for - currently 10,000. Since the comm pipe does not carry every channel, it is not a limiting factor.
How many channels can a house receive at the same time? - Four. There was a brief deployment of seven. But, they can be any four/seven of the 10,000 available. This seems adequate for most families and inadequate for some.
02-23-2014 6:32 PM
Third... Can I presume that the video data between the VRAD and the STB is in one of the MPEG formats? I had some dealing with this before I retired from Harris Corp a couple years ago; may have to go hat-in-hand back there and ask to borrow a couple textbooks....
Yes, the system works like this:
When you change channels on a set-top-box unit, the STB sends out two requests on the network. First, it sends a request for an IP unicast transmission of the channel. The unicast transmission begins coming to the STB unit within about 1/4 second, which is what gives U-Verse it's fast channel changes compared to cable or satellite. The STB also sends out an IP multicast group join request to the next upstream router (your residential gateway), which forwards that join request to all upstream routers. Within a few seconds, the IP multicast stream of the same channel begins coming into your house and gets received and decrypted by the STB.
The multicast stream is ahead of the unicast stream by about 3-5 seconds, so the STB buffers the multicast stream internally in memory (and also buffers it on the hard disk so that you can get FF/REW on the DVR unit and the STB units via whole-home-DVR). It then seamlessly switches your viewing from the unbuffered unicast stream to the buffered multicast stream about 10-15 seconds after you changed the channel, and then drops the unicast stream.
You'll notice that immediately after you change channels, the trick play (FF/REW) functions are not available. The STB doesn't enable those until the shift to the multicast stream is completed.
The system has several advantages:
The VRAD box near your neighborhood is actually kind of a dumb device. It's main purpose is a media changer, changing from 10 Gb ethernet delivered by fiber over to VDSL delivered on copper. It has no routing functions, and doesn't participate in the multicast group joins/leaves. The next upstream router on the network beyond the residential gateway is in the AT&T central office.
03-02-2014 7:37 PM
Just a nit pock- CWA is Communicatio Workers of America, which encompasses the many variamts of supplying communications. Copper wire to coaxial cables to Fiber Opticd, to whatever the next technolgies, including the wireless edge to 4G LTE
to 5, 6, 7 etc. G, analog to digital multiplexing, fiber rings on and on and on
Not sure what you're trying to say. Communication Workers of America (CWA) is a union that covers many AT&T technical employees, as well as those of other Telephone companies.
03-02-2014 8:03 PM
03-05-2014 3:24 PM
03-06-2014 8:07 PM
The reply function is lacking, it is understandable that there was confusion. I should have said to whom and what I was responding.
Perhaps the site gurus can make it automatic like some community boards do?
Sorry for nitpicking and all the typos frim my tiny keyed iPhone.
Ah... the interface is quite different between the mobile site and the full PC site. You do lose the ability to quote. Even on the PC interface, the non-linear reading listing drives me crazy and I enable it only in desperation when trying to sort through whose reply goes to where.
04-15-2014 9:45 AM
U-verse technician are a joke. They have been coming to install my services for two weeks. They keep reporting in the system that they have been to my house or called and left voice messages but that is not the truth. I've missed a total of 16 hours from work trying to have services installed but that is not the case. I have been told by several respresentatives that I am a valued customer yet I have been treated like an outcast. I want my services installed and I need my internet to perform part of my job duties. I cannot express the frustation that I've expressed behind this matter. I was also informed that my services will be installed on today guranteed. I will keep you all posted.
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