256-fold (or even more) increase in speed on copper wirepossible IMHO
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From: Grant Edwards on 11 Mar 2010 14:53 On 2010-03-11, RalfM <rm(a)invalid.invalid> wrote: > Tim Wescott wrote: >> RalfM wrote: >> >>> but instead of transmitting just 1 bit per cycle use instead say 8 >>> bits per cycle, >>> ie. 8 DC voltage levels much like done with a DAC and ADC. >> >> That's been fiddled with. About the only place that it's really popular >> is over really long stretches of wire. If the wire run is short (e.g. >> USB, IEEE-1394, LVDS), or if it can be well controlled (e.g. lower speed >> Ethernet) then the signaling is usually binary with some sort of BEC, or >> FEC combined with BEC. > > Hmm. I don't understand why restrict yourself to use only binary > signalling Because it's cheap, reliable, and works well. > when it can be done byte-wise (or even more) in the same > time. _You_ claim it can be done. Everybody else seems to have failed and chosen methods like phase/amplitude modulation and various other schemes. > This could dramatically increase the speed, regardless of the > distance. Again, you seem to be making a claim that contradicts what everybody who has worked in the data communication industry has experienced. -- Grant Edwards grant.b.edwards Yow! MMM-MM!! So THIS is at BIO-NEBULATION! gmail.com
From: Grant Edwards on 11 Mar 2010 15:17 On 2010-03-11, RalfM <rm(a)invalid.invalid> wrote: > Grant Edwards wrote: >>>> Think a little bit about how noise picked up by the transmission line >>>> will affect the reading at the receiver. Also consider the case >>>> where the transmitter and receiver have different ground references. >>> >>> I think they can be solved easily [...] >> >> Go ahead. >> >> I'm sure all those engineers at TI, Bell Labs, DEC, Intel, HP, etc. >> were all wrong. > > I think they all thought of only bit-serial transmission, not going > further in the dimension. 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. >> You're going to have a lot of problems with waveforms changing too >> much. Have you ever looked at any eye-plots and and compared what >> comes out of the far end of a cable with what goes in? >> >>> by (a) using a twisted pair cable per direction, much like in >>> Ethernet, and (b) one of the wires would be the common ground and the >>> other obviously the DC level against the ground wire. The only >>> problem I see is to have a DAC and an ADC which can switch fast >>> enough the DC levels. But I remember having seen in the >>> specifications of these chips that they can well do several Mega or >>> even Giga samples per second, so then it should suffice IMO. >> >> Do you think that everybody goes to such measures to avoid DC >> signalling just for fun? > > My understanding is that one can do it better, faster, and cheaper. To what does "one" refer? > For example 1000BASE-T uses 4 pairs (!) of wires, And each of those pairs carries multiple bits per symbol using 5 signalling levels. > 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. Then go off and _do_it_ and quite blathering about it. > If byte-serial works then why not improve it further simply by using > multiple bytes per cycle. Because it's hard enough correctly transmitting a dual-state signal. It becomes exponentially more difficult to transmit mutli-level signals. > Ie. one could transmit even 32-bits in just 1 clock cycle; Dream on. > it all depends only on the max range levels the DAC on the sending > side and the ADC on the receiving side can distinguish. 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. -- Grant Edwards grant.b.edwards Yow! A can of ASPARAGUS, at 73 pigeons, some LIVE ammo, gmail.com and a FROZEN DAQUIRI!!
From: Grant Edwards on 11 Mar 2010 15:18 On 2010-03-11, Vladimir Vassilevsky <nospam(a)nowhere.com> wrote: > Are you Radium the Troll ? 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. -- Grant Edwards grant.b.edwards Yow! Oh my GOD -- the at SUN just fell into YANKEE gmail.com STADIUM!!
From: Grant Edwards on 11 Mar 2010 15:42 On 2010-03-11, RalfM <rm(a)invalid.invalid> wrote: > It is IMO so simple and easy. 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. -- Grant Edwards grant.b.edwards Yow! I was making donuts at and now I'm on a bus! gmail.com
From: Rob Gaddi on 11 Mar 2010 16:06
On Thu, 11 Mar 2010 21:41:25 +0100 RalfM <rm(a)invalid.invalid> wrote: > Grant Edwards wrote: > > > > 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. > > And, what about just 256 levels? Would that be impossible too? > Yes. In the immortal words of Willow Rosenberg, "Bored now." -- Rob Gaddi, Highland Technology Email address is currently out of order |