From ascen@world.std.com Tue Jan 24 13:20:49 1995 Return-Path: Received: from mx4.u.washington.edu by stein2.u.washington.edu (5.65+UW94.10/UW-NDC Revision: 2.32 ) id AA02931; Tue, 24 Jan 95 13:20:49 -0800 Received: from hitl-new.hitl.washington.edu by mx4.u.washington.edu (5.65+UW94.10/UW-NDC Revision: 2.31 ) id AA01025; Tue, 24 Jan 95 13:20:48 -0800 Received: by hitl.hitl.washington.edu; id AA16926; Tue, 24 Jan 1995 13:16:55 -0800 Received: from uucp2.UU.NET by relay3.UU.NET with SMTP id QQyacr04092; Tue, 24 Jan 1995 16:20:54 -0500 Received: from world.UUCP by uucp2.UU.NET with UUCP/RMAIL ; Tue, 24 Jan 1995 16:20:47 -0500 Received: by world.std.com (5.65c/Spike-2.0) id AA13125; Tue, 24 Jan 1995 16:19:26 -0500 Newsgroups: sci.virtual-worlds Path: ascen From: ascen@world.std.com (Ascension Technology) Subject: Re: TECH: Tracker Technology Questions Message-Id: Organization: The World Public Access UNIX, Brookline, MA X-Newsreader: TIN [version 1.2 PL2] References: <3fmj3g$d56@nntp1.u.washington.edu> <3g19pg$8pq@nntp1.u.washington.edu> Date: Tue, 24 Jan 1995 21:19:24 GMT Lines: 50 Apparently-To: uunet!sci-virtual-worlds@uunet.uu.net Status: OR : Other than a black hole, I can not imagine too many ways to fool the pitch : & roll sensors. The Yaw sensor can be affected by strong magnetic fields : (at the NY Meckler show, we ran into a problem trying to run it within ten : feet of an Ascension Bird). Strong magnetic fields at 10 feet from an Ascension standard range transmitter? If the field was strong (compared to background noise) we would have the range to 10 feet. We wish we could get a strong signal out to 10 feet, but the transmitter required would be huge, as would the electrical bill. Our standard range transmitter running full power has a magnetic field strength of less then 1/16 Earth's magnetic field at 3 feet (it's specified range limit). 1/16th earth's magnetic field is 37.5 milligauss, and dropping fast. At 10 feet I expect the 'noise' to be less then the noise from your computers power supply, or CRT. The ERT puts out more power, but none was used at the NY Meckler show. Are you sure the interference was not from your own electronics? :^ Do you 'calibrate' your system on startup? The Earths magnetic field vector changes as one moves around on the surface of the earth. I don't have the charts with me at this moment, but if I recall correctly around the US the vector changes a few degrees. And building's magnetic effect. It is not uncommon to have the metal substructure to introduce a distorting magnetic effect. What do you do about these effects? Drop me some email, I would like to talk technical with you. Email ascension@world.std.com. or call (802) 860-6440. Regards, Steve Work Technical Support Ascension Technology Corp