[geeks] Synchronus Serial

[Ken Hansen]

See below...

----- Original Message -----
From: "Brian Hechinger" <wonko at arkham.ws>
To: <geeks at sunhelp.org>
Sent: Tuesday, July 31, 2001 9:48 PM
Subject: Re: [geeks] Synchronus Serial


> On Tue, Jul 31, 2001 at 09:32:24PM -0400, Ken Hansen wrote:
> > 3-400 mines is a *huge* distance in radio terms...
>
> hmmmm.  what is a "reasonable" distance to be able to expect nice
performance? LOS?

I, Cringely had a column or to about an 11 mile 802.11b link using expensive
antennas ($275) - he later found out about easy to make alternative that
cost an order of magnatude less ($25)...

Reliable communication over 300 miles would require special antennas
(beam/directional with *mucho* gain), and large power (to drill through any
sun spots/"skip").

Anyone know how far phone company microwave towers are from each other?

> > VHF/UHF require line-of-sight - hard at that distance to be sure.
>
> they do?  i didn't think so.  i could very well be wrong though. :)

Yes, their freq. "punch through" the ionosphere, lower freq. reflect (or
"skip") off the ionosphere...

> > HF would limit speed of data (bandwidth concerns) I suspect...

Not sure, but if you are going to run 10 Mb/s over a radio link, you will
need more than a 10 KHz "channel" - how much spectrum (bandwidth) does
10Base2 use on a piece of coax?

A TV signal requires 6 MHz, and sends less than 10 Mb/s information (I
think)...

> what is the theoretical upper limit?

not sure...

Ken



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