Oops. Cancel what I said below. We are talking at cross purposes. You are of course correct. Joe -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Joe McCauley Sent: 13 May 2003 15:10 To: PICLIST@MITVMA.MIT.EDU Subject: Re: [OT]: Underwater navigation The premise behind this was probably to mark the boat position as a waypoint before entering the water. The GPS would then be able to give a bearing to that point from the current position which would be updated as the diver moved. No actual movement would be required to get the bearing to the waypoint from the current position. See my previous post for reasons not to use this type of method. Joe -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Sean H. Breheny Sent: 13 May 2003 15:00 To: PICLIST@MITVMA.MIT.EDU Subject: Re: [OT]: Underwater navigation I have no actual experience with GPS receivers so perhaps this is just showing my ignorance, but how does it indicate direction? Sure, it knows that you need to go, say, Northwest to get to your destination since it knows where you are and where the destination is, but since it doesn't know the orientation that you are holding the GPS receiver in, it can't give you an arrow telling you which direction to move in. You would have to move first so that it could give you a new position and determine the direction that you moved. In other words, since GPS cannot tell orientation but only position, and a point doesn't have a direction to it, only a vector, it would seem to me that it needs some movement in order to tell you whether you are moving in the right direction. Sean At 09:09 AM 5/13/2003 -0400, you wrote: >I stand corrected - Direction it gives, speed requires movement. > > > Given two points (boat's location when you left it and swimmer's > > current antenna position), bearing and distance information do not > > require movement. If your GPS requires movement before it shows > > you this information, they you should get another GPS. > > > > Speed requires some minimum amount of movement before the data > > is usable. But I get a reasonable speed readout while walking > > with my Garmin handheld. > >-- >http://www.piclist.com hint: The list server can filter out subtopics >(like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics