> Hello guys,
> I just got the $15 ethernet cards working between my linux and
> win-95 computers. They can be configured to be ne2000 clones and work
> very well in this mode.
>
> These are 10K2 devices and I suspect the details of the waveform
> that they generate into the coax links is well known. So why can't we
> use the ethernet card as our TNC and build data radios that have 10 MHz
> bandwidth?
>
> In other words cash in on the diskless generation?
I think the main problem of using ethernet cards over radio
is the high bandwidth of the radio channel that would be required.
As an ethernet card transfers 10 Mbit per second and uses Manchester
coding as far as I know, I suppose at least 10 MHz (probably
more) bandwidth would be necessary for a radio transmission. This would be
possible in microwave bands only where enough frequency space is
available for a single channel -- in Europe nothing beyond 10 GHz.
These high frequencies require that the antennas can directly "see"
each other, which is not possible in most cases, except between
two stations which are both placed at an exposed location. Another
problem is that this kind of links are point-to-point links due
to the high frequencies; they could perhaps be used as a
backbone for digipeater networks, but not for multi-user access
to a digipeater.
73 de Andreas
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Andreas * DG3KQ * Aachen, Germany * JO30BS
e-Mail: nnyu.ganc@demos.net