This is purely for your edification and you need not be worried about it. However for those of you who are curious as to why dialup connections are pretty well forever limited to 56k and why you need different techniques to communicate any faster, I introduce you to Shannon's Law.

Shannon's Law, by the way, works just as well for radio frequency as well as wired communications, which also explains why wireless connections can show effective data transfer rates well below theoretical.

Interestingly enough, it used to be thought that 2400 bits per second was the Shannon's Law limit, but that was before the engineers realized you could overlap the transmitting and receiving "channels" in a modem. The 33.6k Shannon's Law limit for analog communications is with full utilization of sending and receiving frequencies, and the 56k Shannon's Law limit for partial digital communications is also with full utilization.

Have you heard of computers using hydro lines for internet connections?

Canadian Company to Offer High-speed Internet Access Via Hydro Lines

There is a pilot project in the Sault St. Marie area using hydro lines to transmit cable and internet.

[ 09 May 2005: Message edited by: forum observer ]

[ 09 May 2005: Message edited by: forum observer ]

Interestingly enough, the first long distance data communications were designed around an already existing public switched telephone network. Analogue voice transmission req'd a ~4KHz bandwith to carry the audible voice range for sound waves. Until the early 1960's?, voice calls were predominantly what the PSTN was used for. Voice circuits eventually went the way of digitized circuits for long distance transmission from between local exchanges separated by great distances. Still, analogue transmission over copper wires is what most of us use between home and local telephone offices, the long distance carriers found ways to concentrate many voice connections over time division multiplexed transmission lines, or T1(DS1) channelized circuits carrying as many as 24 digital connections, or DS0's. And there is a formula for calculating bit rate for T1 and still adhering to Nyquist's rules of pulse code modulation(digitization of voice as well as data):

24 Channels
x 8 Bits per Byte Sample(Nyquist rate)
_____________
192 Bits
+ 1 Framing Bit(193bits= 1-T1 frame)
_____________
193 Bits
x 8,000 Frames per Second
_____________
1.544 Mbps - North American T1 Std(Europe E1=2.048Mbps with 30 DSO's)

In North America, every sixth(and sometimes more often than that) least significant bit of an 8-bit channelized sample is "robbed" by the bigger picture communication layer called "SS7"(more or less adhered to globally) for various network signaling control, hence the name, robbed bit signalling or ABCD signaling. Of course, with ISDN as an example where digital is end-to-end over two 64kbps bearer channels, one for upstream and the other downstream, the extra 8 bits are not lost to signal control and full 64kbps might be uitilized for data communication bandwith.

I don't know about the state of power line tech, ForumObserver. Think of all the electrical appliances and producing electrical "noise" in the average home. That's got to be a factor. Power companies in Britain were investing billions during the 1990's in this particular area of data comm. Nortel and one other Canadian company were involved, by what I know.

[ 09 May 2005: Message edited by: Fidel ]

Thinking about the impact of powerline communications on society, I’m reminded of Edison who said, in the nineteenth century, ‘I shall make the electric light so cheap that only the rich will be able to burn candles.’ When Edison said that, there were no wires, no generators, and, most importantly, no electric lamps. We at Amperion have a chance to analogously change broadband in a most profound and meaningful way.

That is until the grid system has been monopolized. Remember, "fight privatization." Fight off any government selling Canadian/Prov ownership of Hydro, and make Canada, "a superhighway run by, free social supported conscientious people":?)

[ 09 May 2005: Message edited by: forum observer ]

quote:

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Originally posted by Rufus Polson:
There are apparently problems with power-line information transmission. It gibbles up some radio frequencies, for instance.

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I would have liked to understand the science better here. Do you have something that would speak to this?

Also, when you think of the reach int our homes, without considering extra lines being run, wouldn't it seem likely, that there is not one location that could not be reached? Country or other wise, that would not rely on satellite communications? Cable? Or telephone lines?

Amateur radio enthusiasts the world over seem to be united in their distaste for what BPL does to the airwaves [16, 17]. This interference has historically scuppered BPL trials. A good example of this is the Nor.Web trial that began in 1998 in Manchester[15]. Despite complaints about the interference and warnings from the Radiocommunications Agency [18], the company consistently rubbished criticism and insisted that the roll out would take place. By the end of 1999, the company had been closed down [15]. In Japan, the technology will not be adopted because of the interference problem [10].