[ct-user] Networking CT over long distances

Glenn_D_Odonnell gdo@aloft.micro.lucent.com (Glenn_D_Odonnell)
Tue, 9 Sep 1997 10:29:35 -0400

Please pardon my long-delayed echo on this subject.  I'm just now catching
up on my CT mailbox.

We in the Carbon ARC in EPA have done this fiber thing for the past few years
and it works great!  We managed to get a 200 foot spool of multimode fiber
complete with ST connectors so we use the full 200 ft.  You should be able to
run RS-232 data rates for several thousand feet over fiber.

Copper runs of a few hundred feet are reasonable with good cable, but as J.P.
points out, the RF can (and probably will) get in and ruin your data.  I've
successfully run RS-232 over 1000 feet of good copper cable in my professional
life.  This was certainly a cleaner RF environment than your typical multi-op
contest station!  :-)

If you MUST use copper over long hauls, you can try RS-422 converters over
BALANCED twisted pair wiring.  This isn't as good as fiber, but MUCH better
than RS-232.  You should be able to buy fiber and RS-422 components from the
common commercial vendors like Inmac and Black Box, but they're fairly

In my opinion, networking over Ethernet (i.e. the K1TTT solution) is the best
bet moving forward.  Ethernet's various incarnations are very RF tolerant over
copper and (hey, we're all hams here!) ... CHEAP!  Twisted pair Ethernet
(10BaseT) cards are dirt cheap now and some newer PCs are FINALLY including
cards or embedded 10BaseT as standard equipment.  Ethernet will soon be as
ubiquitous as COM ports are today.  By the way, Ethernet also runs over fiber,
albeit more expensive.  Ethernet, with TCP/IP protocols is poised to enable
capabilities we have yet to conceive.  Buckle up, it's going to be quite a
ride as this stuff becomes reality!

Ethernet can also go wireless.  Hey, where did I hear THAT "W" word before?! 

73 de Glenn, K3PP

> J.P. Kleinhaus, W2XX wrote:
> The WECA Field Day effort has been experimenting with networking
> CT over runs >200 feet with varied success.  This year, we finally
> got it all working. The trick was to use fiber optics to make
> the links, using small fiber modems at the serial ports.  The
> outer limits of this system are probably in the neighborhood
> of 250 feet or so.
> Obviously, RF won't do anything to the fiber signals, but you
> need clean output for the sytem to work right.  If you have an
> "RF clean" environment, high power shouldn't be an issue.  If you
> attempt this with regular serial cables, I doubt you'll ever get
> it to work.
> K1TTT has been experimenting with an ethernet TSR for CT that
> allows regular network hardware (ethernet/coax) to run.  I am
> not sure how he is progressing with that project.

Submissions:              ct-user@ve7tcp.ampr.org
Administrative requests:  ct-user-REQUEST@ve7tcp.ampr.org
WWW:                      http://www.ve7tcp.ampr.org/Software/ct
Questions:                owner-ct-user@ve7tcp.ampr.org