From: email@example.com (Paul Kearney) Date: 13 Mar 2000 09:56:46 -0800 Organization: Ireland On-Line Customer References: 1 Followups: 1
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Ed McBride <firstname.lastname@example.org> wrote: ::But I keep hearing that people take off in an airplane, fly across ::country, and know where they are within a foot or so. The only ::explanation I can come up with is that these airplanes must be ::"re-zeroing" rather often. The INS/IRS systems on Boeing Aircraft (assume very similar on others) use the DME(radio ground stations) to confirm and update their position as they travel. Now with GPS - the NAV systems can be updated even when out in the Atlantic/Pacific where DME may not be available. Which i suppose is ''re-zeroing'' itself. The B737 Flight Managment Computer uses DME/DME cross-bearings to confirm its location when it knows that it has 2 DME's to work with. But... your machine wont have this luxury... i take it that youre talking 3-D for your own project and therefore counting stepper-motor pulses on a known diameter wheel to indicate position change from known-origin would be useless ?? good luck with the project anyhow. paul.