Re: Wireless CU-SeeMe

John D. Balogh, +1 814 863 1252 (JohnBalogh@psu.edu)
Wed, 08 Mar 1995 08:16:58 -0500


>At 19:03 3/7/95, David Watson wrote:
>>In a recent post some one commented that they were getting 2mb/s on a radio
>>link and I was impressed. Looked to the site listed by Micheal Sattler,
>>http://www.metricom.com, and drew the following down. How was 2mb/s
>>achieved?
>
>Certainly not over a Metricom modem, which does 100 kbps one-way or 56 kpbs
>for SLIP/PPP kind of connection. You may be referring to Patrick Stigley's
>posting. Pat?

Or mine...
We're using KarlNet stuff here at Penn State. 2Mbps is achieved with
the ISM band from 902-928MHz and direct-sequnce spread-spectrum.
Actually 2M out of 26MHz of bandwidth isn't all that hard; almost like
getting 300bps out of 3,500Hz of bandwidth on a phone line. :-)
There is another version of the WaveLan board that runs in the 2GHz
ISM band (if there are too many 900MHz portable phone weenies near
your site this helps).

The raw boards to do this are avilable from DEC and NCR. The chipset
on the board is NCR/AT&T Global Information Systems. There is a socket
for a DES encryption chip and KarlNet adds an additional level beyond
that in their ethernet/RF bridge/router product (as well as SNMP).
Directional antenna are $50 - $200 (depending on gain and configuration).
You can get more info from <sales@karlnet.com> (no involvement here,
just a satisfied user :-).

We like the ethernet solution because then we arn't strapped to a
particular bus (the WaveLan cards are only available in PC/ISA bus),
so connecting a MAC means dropping an Asante ethernet board in
and plugging a cross-over 10baseT cable between the MAC and the RF box.
Only the "home" users with SGI-Indy or Sun-SparcClassic boxes actually
tax the link to near its limit.

Hope this helps.

-
Name/Rank/Serial#: John Balogh, Systems Engineer, JohnBalogh@PSU.EDU
Employer: Penn State University, Office of Telecommunications
Phone: +1 814 863 1252 Fax: +1 814 863 4092
SNAILmail: 101 TELECOM, UNIV. PARK, PA 16802-5800, USA
WWW: http://jdb.psu.edu/john.html