Re: DSL - How much can really fit in an old 1mm copper wire?

I just got an offer from a company who wants me to switch ISP. They’ll give me 24MB down, 1 MB up and HDTV, all through my phone connection. According to them, I’ll be able to play games online, talk on the phone and watch TV at the same time.

My apt. building is from the late 50’s and the copper wires for the phones are from that same time. I’m aware that electrons are very small, as compared to a one mm wire, but still… A few years ago, supposedly optic fibres was the only way we were gonna get true high speed broad band. And if they can fit HDTV, why can’t they increase the upload rate?

Hereya go!

It is not so much that you need to get many electrons through it (you don’t need high current). You need to be able to change the voltage rapidly at one end of the wire by changing it rapidly at the other end. This depends a lot on the capacitance of the insulation, and on how long the wire is.

But I don’t know what the limit is or exactly how to predict or measure it.

The ordinary telephone system is artificially bandwidth limited at about 3.4 kHz, however the lines themselves are capable of transmitting much higher frequencies.

According to several sites accessed by searching Google for “telephone lines+DSL” it is entirely possible to have DSL + TV + voice all at once.

Gotta call BS on this one (not you…the vendor). Do you have a link to their offerings?

IIRC DSL maxes out at around 8 mbps down and like 1 mbps up (not 100% certain but somewhere in there). Those speeds are assuming you are practically on top of the nearest central office. The farther away you go the slower it gets. So, 24 mbps down is just wrong unless they use some kind of multiplexing DSL and drag 3 or more lines to your house to do this. Never heard of that being done with DSL but I suppose it is technically possible.

I’d look at the small print closely.

I work for a telephone company (not one of the bells) that is currently providing digital TV over the existing copper lines. We can deliver three streams of video, 1.5M down and 512K up and analog voice service on 12mbs ADSL2+ equipment.

One of the projects I am currently working on is a strategic plan to provide the ever increasing bandwidth demand. At this time, the only way we can deliver the bandwidth needed for 24M data, and HDTV video is with Fiber To The Premise (FTTP).

Are you sure they will provide this service over copper, or is there a FTTP project going on in your area?

If they are doing this with copper, please let me know how they are doing it because I would be a hero at work with that kind of information.

Yahoo! BB provides SD DTV cable via DSL (Japanese link) in Tokyo, although IMO not very successfully. There are constant drop-outs that pixelate the picture horribly, and the screen blanks frequently enough to make programs nearly unwatchable. Of course, my experience is anecdotal, as I’ve only known a few people who had the service. However, it’s telling that everyone I’ve spoken to who has taken Y!BB up on their free offer has declined to retain it afterwards, despite the very high price of cable there.

Yahoo! BB also offers a 50 Mbps down, 3 Mbps up ADSL service (another Japanese link). Seems at odds with what the technical references claim about ADSL (note that Yahoo! requires you to have an NTT phone line, so it’s clearly conventional ADSL).

It is rumored that the relatively slow upload you see with most (all?) DSL is a marketing decision aimed to discourage hosting on DSL, not a technical issue.

I’ve got to question the rumor. My telephone co., Verizon, offers its own DSL and I use it. It is more likely done in order to preserve bandwidth space at higher pulse rates for TV and other utilities.

I don’t know what the bandwidth of regular 'ol telephone cable is. But whatever it is, there is a limit on the maximum amount of digital data that can be transmitted.

The link is in Swedish, and I have no idea how it works. The fine print says that the speed of the VDSL (not ADSL), will vary depending on distance from the phone station, but since I live very close, I’m guranteed 8 MB down, which I can verify, using a handy little tool that checks bandwidth.

I read the link to howstuffworks, but it didn’t really tell me anything new. In fact, it raised more questions, as it seemed to imply that there is in fact an upper limit on the DSL technology. How they’re gonna squeeze in live feed digital tv, then is beyond me.
If it does work, and gives good picture, I might contemplate switching.

I live in an old building and was offered DSL a while ago, but the hitch was that it’s unusable if the building’s intercom goes over the phone line. So if your building’s intercom goes through your telephone you should let the DSL provider know about it. It could be a deal breaker.

Patient with broken wrist to Doctor: “After this has healed will I be able to play piano”

Doctor: “Yeah, sure”

Patient: “That’s amazing”

Doctor: “Not really, it’s just a broken wrist”

Patient: “But you see, I couldn’t play piano before.”