256-fold (or even more) increase in speed on copper wire possible IMHO

levels.

bit cable" :-) or more.

I think they all thought of only bit-serial transmission, not going further in the dimension.

My understanding is that one can do it better, faster, and cheaper. For example 1000BASE-T uses 4 pairs (!) of wires, IMHO a waste of wires and HW. I think one can do it with only 2 pairs if one just uses "byte-serial" transmission instead of bit-serial. If byte-serial works then why not improve it further simply by using multiple bytes per cycle. Ie. one could transmit even 32-bits in just 1 clock cycle; it all depends only on the max range levels the DAC on the sending side and the ADC on the receiving side can distinguish.

Reply to
RalfM
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Are you Radium the Troll ?

VLV

Reply to
Vladimir Vassilevsky

Then you're deluded. They thought up all sorts of methods that aren't bit-serial. Modems, Ethernet, and disk drives all use transmission schemes that aren't bit-serial.

To what does "one" refer?

And each of those pairs carries multiple bits per symbol using 5 signalling levels.

Then go off and _do_it_ and quite blathering about it.

Because it's hard enough correctly transmitting a dual-state signal. It becomes exponentially more difficult to transmit mutli-level signals.

Dream on.

You seem to have forgotten there's a cable between the two. A cable with capacitance, inductance, resistance, and a _lot_ of noise coupled onto it.

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Grant Edwards               grant.b.edwards        Yow! A can of ASPARAGUS,
                                  at               73 pigeons, some LIVE ammo,
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Reply to
Grant Edwards

I've decided that he's definitely a troll.

Nobody with more than five firing neurons would think they could send

4 billion different DC levels down a cable and correctly discriminate them at the far end.
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Grant Edwards               grant.b.edwards        Yow! Oh my GOD -- the
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Reply to
Grant Edwards

Perhaps his brother?

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Tim Wescott
Control system and signal processing consulting
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Reply to
Tim Wescott

It is IMO so simple and easy. Let's say we use a 5.12V DC source, then we divide this by 256 and get 20 mV DC range for each of the 256 codes in a byte. Now tell me where is the problem to transmit the output of such a DAC over a twisted pair wire and use the reverse process on the other side by using an ADC?

For full-duplex one of course would need 2 pairs of twisted wires. It all depends on the speed of the DAC and the ADC, and they are IMO sufficiently fast. For example 1 Gbps means 125 MB/s. Then a byte could be sent in 8 ns. Ie. the DAC and ADC would need to have a sampling rate of 125 MSps, and I think this is easily possible with todays chips.

My preliminary calcs indicate that one even could get 1000 GBps and more with this method, ie. at least 10 times more than the draft 100 GBps Ethnernet.

Reply to
RalfM

And, what about just 256 levels? Would that be impossible too?

Reply to
RalfM

Congratulations for hooking as many people as you did.

This has been a very nicely done troll, but you tipped your hat when you started making claims like it would be simple to use 2**32 distinct signalling levels.

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Grant Edwards               grant.b.edwards        Yow! I was making donuts
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Reply to
Grant Edwards

1.2 nV range per code. Is this impossible with todays technology? But 32 bit was just an example. Let's stay at 8 bit.
Reply to
RalfM

You have _no_ idea. None at all. Really.

You're basically calling 100+ years' worth of study in electrical signal transmission theory worthless, purely on the basis of what _you_ "think they all thought". Well, think again.

Better yet, stop writing for a while and use the saved time to read up on the subject before you embarrass yourself any further. For starters let me suggest you look up, and _understand_ all of the following transmission standards:

56kbit/s analog modem over POTS ADSL/SDSL technologies QAM-256 modulation used for digital cable TV Gigabit Ethernet

That understanding lacks both completeness and correctness in rather critical amounts.

You've been investing an awful lot of bandwidth here into proving that the 'H' in that 'IMHO' is a lie.

Reply to
Hans-Bernhard Bröker

Of course true, but 256 levels should IMO be within reach with todays chips...

Reply to
RalfM

The problem is that what comes out of the cable is quite different than what you put into the cable, especially at high signaling rates.

You are forgetting the most important part; the cable in between. Twisted or not nasty things happen to the signal, and I'm not just talking about noise. Consider what the frequency response, impedance, inductance, capacity...etc of the cable would do to the signal. Of course if the termination is less than perfect you would have to consider reflections as well.

Ignoring the fact that you would also need to devise a way to extract a clock from the signal you send over the cable, it would even with a very short cable it would be at best very unreliable.

Only in your fantasy, reality is quite a bit more complicated. Just take

100 meters of cable and actually try your method with signaling rate 1 MB/s. To maximize your learning experience hook up a scope.
Reply to
Dombo

Yes. In the immortal words of Willow Rosenberg, "Bored now."

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Rob Gaddi, Highland Technology
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Reply to
Rob Gaddi

Ummm, Ethernet isn't DC.....

Be a bit tough to get those DC voltages through the isolation magnetics, wouldn't it?

Reply to
WangoTango

Wrong. I have my own unchewed ideas:-)

That's analog. I'm interessted in digital technologies.

A waste of bandwidth by splitting it into 2 or 3 channels instead of transmitting everything equally in digital packets, incl. voice, by using a priority code in a header frame field. But this is already above the wire level. Im talking of the low-level wire level.

I have the feeling the computer network engineers can learn much from the digitial cable TV engineers as the latter seem to have much faster transmission speeds (just imagine trasmitting about 1000 (!) cable TV channels over just 1 coax cable!). I wonder why the same underlying technology is not used with computer networks to make much faster network transmissions possible over plain old copper wire.

Reply to
RalfM

To all the people who have dicussed this topic:

Imagine Satellite TV: it is possible to get more than 1000 TV channels via the dish. Now this is a huge data rate and data quantity that gets received by the dish and made available in the receiver. Now, what do you think: is a satellite link faster than a cable link? I think a cable should allow more capacity and reliability than air transmission. But then why don't we see such transmission rates in computer networks?...

Reply to
RalfM

A few months ago, Circuit Cellar Ink ran a lovely article by Robert Lacoste that showed what happens when a signal hits off-impedances in a transmission line. ISTR in one of his examples you could see the reflections from the co-ax connectors. I can't seem to find that issue, but in the December 2009 issue the same author has written "Digital Modulation Demystified." Imagine that!

Mel.

Reply to
Mel

go look up the Shannon=96Hartley theorem

-Lasse

Reply to
langwadt

transmission.

Which is digital encoded as analog (frequencies, phase and amplitude) as you cannot transmit DC levels even by satellite.

Probably do this and have tried building networks like this, for computer networks it can get expensive, for the amount you actually use where by on computer does not need to tune into one of many channels. The nearest analogy to that is WLAN.

Multiple channels over one piece of copper has been done, before it is/was the basis of telephone trunk lines.

Do some basic research as you do not understand how things currently work.

Like others I consider you a troll.

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Paul Carpenter          | paul@pcserviceselectronics.co.uk
    PC Services
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Reply to
Paul Carpenter

Down a few inches of cable between a DAC and ADC well tuned, in a shielded box, preferably with its own battery supply, driving the signal at least +/-10V signalling levels.

Forgetting all other aspects, get 100m of cable, lay it out on the ground (to avoid coil effects), put a DC level in one end and put a receiver circuit on the other end and try putting a 5V triangle wave in.

On the receiver place an ADC on the far end and using same clock feed it into a DAC, and scope the signal from the DAC and see how many missing codes and lack of amplitude you have.

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Paul Carpenter          | paul@pcserviceselectronics.co.uk
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Reply to
Paul Carpenter

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