[comp.dcom.telecom] Information Needed on Moderate Range RF LAN

jst@ccnext.ucsf.edu (Joe Stong) (01/11/91)

As usual, I want to do some reasonably inexpensive computer to
computer data connection between two sites that are diagonally across
a street from each other (building to building is about 500 feet). If
any of you gadget freaks out there can refer me to some sort of short
to moderate range RF LAN, send me mail.  Or any interesting solution
involving those short range TV transmit/receive systems for your VCR,
and some inexpensive serial or ethernet to TV channel
modulator/demodulators.

I've only seen one, reasonably low speed solution, an RF modem device
called a "LAWN" ($600 gets you 19,200Baud and 500feet, maybe).

I'd love to climb into the underground utility tunnels and string some
coax, and do ethernet between the buildings, but I haven't a clue as
to who to ask, and what bureaucracy I'd have to go through to do it.
It is a city street.  How do companies like the cable TV folks get the
rights to cut slots in the pavement and insert coax, or string wires
on the poles, or run wire through whoever's underground tunnels?  Who
owns the tunnels and or the poles?

The last time I dealt with a leased line, it was between a couple of
buildings that were about two blocks from each other.  The leased line
was something like 6.5 miles long, because the phone company required
that the line go across town to the phone company and back to the
other building.  This was in order that they could leave a butt set
parked across the line in the phoneco office so that it would short
out the feeble pulse carrier stuff that the short haul modems were
putting out.

It also appears that leased T1 is ordinary pairs, but you get shielded
twisted pair in to your building.  You mean that MOST pairs in the
cable on the street will carry 1.544 MBaud?  ISDN at 128Kbaud must be
trivial on those pairs, then.

Given that MOST of the expense of phone service is probably generated
by the equipment and personnel required to do itemized billing of
calls, and not for the service itself, is there any technical reason
that we couldn't have >128Kbps Internet jacks installed on our home
and office walls for $30 a month, flat rate, by the phone company?
(Instead, we may, after much struggling, get ISDN, which would be
charged packet by packet for point-to-point connections, from which
they can milk more money).  (The rationale for the above rate and cost
is that an existing voice line costs maybe $15 a month for 56Kbaud
plus A/D and D/A conversion and the equipment to log call source and
destination.  I'd expect the cost to be similar for a router that ran
at similar baud rates.)

My short term interest is to find a cheap solution for me.  However,
I'll be delighted if I generate some discussion about the general
philosophy and economics of data connections through the phone
companies.  Send me mail and post, I can't keep up with the volume of
comp.dcom.telecom.


Joe Stong   jst@cca.ucsf.edu