Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!decwrl!sun!pitstop!sundc!seismo!uunet!munnari!otc!metro!basser!natmlab!ditsyda!megadata!ed
From: ed@megadata.oz (Ed Rapsevicius)
Newsgroups: comp.dcom.lans
Subject: Token Bus carrier band modem - help
Message-ID: <331@megadata.oz>
Date: 6 Feb 89 01:44:53 GMT
Organization: Megadata P/L, North Ryde, Sydney, Aust.
Lines: 20

Help! We are using the Motorola MC68824 Token Bus Controller
with the Siemens SAB82511 token bus modem, and we have a
series of diagnostics running such as internal loopback, and
external loopback through the medium transformer. However
we seem to have two problems:

    1) We cannot acheive a reasonable Silence threshold, even
       though we have a double sided PCB with a large ground
       plane around the main components. We are getting a
       threshold of around 20 dBmV instead of 4.

    2) A modem will receive its own transmission correctly,
       but doesn't receive another modem's transmission.
       The best we can do is a bad signal status.

If someone has successfully designed in this chip set, can
they perhaps mail some of their experiences to us.

Ed Rapsevicius (ed@megadata.oz, ed@megadata.oz.au)
Megadata P/L, North Ryde, Sydney Australia.
D