[MLB-WIRELESS] Whats Faster ??

[Mathew McKernan]

----- Original Message ----- 
From: "Donovan Baarda" <abo at minkirri.apana.org.au>
To: "Steve Smithies" <steve42 at gmx.net>
Cc: <melbwireless at wireless.org.au>
Sent: Tuesday, August 12, 2003 10:30 PM
Subject: Re: [MLB-WIRELESS] Whats Faster ??


> On Tue, 2003-08-12 at 16:49, Steve Smithies wrote:
> > MP> I am wondering what is faster for transfering data. ie. Out of
Wireless
> > MP> (2.4Ghz), Copper (Cat5e etc) and Fibre Optic, which signal travels
the
> > MP> fastest from point A to point B ??
> [...]
>
> The reason radio waves travel at the speed of light is; it is light.

Isn't light an electromagnetic wave. And radio waves are electromagnetic
waves?

>
> > As a side note, the actual flow of electrons in copper is much much
> > slower. I've gone and forgotten the formula, but remember at high
> > school calculating that for something carrying like 2 amps through
> > 2mm wire, the electrons were only moving about 6cm/second.
>
> The reason electrical signals "travel" through wire at nearly the speed
> of light is the electron's don't move that fast, the "voltage
> difference" does. With a hose full of water, when you turn on the tap,
> water starts coming out the other end almost immediately, you don't have
> to wait for the water leaving the tap to arrive at the nozzle before
> water starts coming out.
>
> With data signals, the speed of transmission only affects latency. It is
> the "speed of transition" that affects data rates. How fast can you
> change the signal, not how long does it take to get there. Of course you
> need to be able to detect the change in signal at the other end too.

You will find wireless will be slower than the cabled variants due to the
management done on the data being transferred, such as error control etc.
Its a lot different to the average fibre/copper connection. All fibre is, is
conversion of the wavelength of the incoming copper data into light. Simple
as that, just provides a much longer run due to the efficiency and the
output power.

>
> Most of the limitations in data rates are caused by "mooshing" of the
> signal transitions. In wireless this comes in the form of multi-path
> affects, reflections, and background noise. In copper it is mainly
> capacitance, inductance, reflections, and "crosstalk" interference. In
> fiber it is mostly multi-path affects.
>
> These all mean that there is a limit to how fast you can transition your
> signal before the transitions start to get lost at the receiving.
>
> -- 
> Donovan Baarda <abo at minkirri.apana.org.au>
>
>
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-- Mathew McKernan


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