OT: Re: How does gigabit ethernet work?

On 11 Feb 1999, Eric Smith wrote: Max writes: 1. They aren't multiple meters long. 2. They actually do have transmission line effects. If you're not careful, there can be enough ringing on the signals (due to lack of proper termination) to cause undesired behavior. If you look at bus signals on a 33 MHz bus with a 100 MHz scope, they look fairly square (unless things are badly designed and/or broken). Now look at those same signals with a 1 GHz scope. The difference is *amazing*. At best, all you can do with high speed stuff is get a good enough *approximation* of the desired digital signal. And the higher the speed the harder it is to make that approximation good enough. When you're talking about "digital" signals above 500 MHz (as would be found on gigabit ethernet twisted pairs), it is very hard to convincingly describe them as digital. Sure, they are enocded from digital bits, and the are decoded back into digital bits at the other end, but what happens inbetween is analog (and basically black magic at that). Eric