Path: utzoo!attcan!uunet!super!udel!gatech!uflorida!mailrus!ames!pasteur!ucbvax!DSUNX1.DSRD.ORNL.GOV!wnn From: wnn@DSUNX1.DSRD.ORNL.GOV (W. N. Naegeli) Newsgroups: comp.protocols.appletalk Subject: Re: AppleTalk noise problems Message-ID: <8809262222.AA00284@dsunx1> Date: 26 Sep 88 22:22:24 GMT Sender: uucp@super.ORG Organization: The Internet Lines: 22 The Tops Repeater will not help you with noise. It is only useful in situations where signal strength is insufficient to be picked up by all nodes on a network with a large effective length. The repeater is simply an amplifier and as such, it unfortunately also amplifies noise. If noise is really your problem you may be worse off with a Tops Repeater. By contrast, the Farallon StarController does not merely amplify the signal but has its own receivers and transmitters and reconstitutes the signal. It will effectively deal with both noise and weak signals, but its cost is fairly steep if you need only two of its twelve ports. I understand that the Farallon NetRelay that has recently been announced with a list price of $500, but is not yet shipping, if I am right, essentially is a similar solution but has only two (or three?) ports and cannot be controlled through network management software like the StarController. It may just be what you need. An ohmmeter can reveal the grossest of network problems, but it cannot detect noise or reflections. With the ohmmeter you can test for continuity and whether network resistance is in the tolerable range. With a Voltmeter you can also test for shorting to other (telephone) circuits and induced currents (both AC and DC measurements should be zero when all devices are disconnected from the net). To detect and pinpoint noise and reflections however, you need more advanced instruments, such as storage scopes with high resolution for timing signals and reflections.