compass considerations continued
in [Mac Systems]
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From: Wes Groleau on 3 Apr 2010 00:38 If a small piece of iron is placed near a magnetic compass, the needle will point to the iron. If a large piece of aluminum is placed near a magnetic compass, it has no effect. If a small piece of iron is placed near an iPhone, the compass pointer changes direction but does not necessarily point to the iron. If aluminum is used, sometimes there seems to be no effect, sometimes it does affect it. After sitting in the middle of my living room while I wasted ridiculous amounts of time on this unimportant topic, I noticed that the iPhone was no longer pointing NW but was pointing approximately north. I removed my keys, pens, etc. from my pockets, so the only metal on me was in my mouth, in my pager (right hip), and around my spectacles. I picked up the iPhone, walked to my front door (steel), opened the steel door, walked out, down the driveway, and into the street. Somewhere between my living room and the curb/kerb, the iPhone began pointing due south instead of north. I walked to the center of the street, and walked the whole length of the block, right down the center. Other than the small amount I was wearing, at no time was any metal nearer than seven meters (street lights near the curb--aluminum). One exception--I passed within two meters of a parked van. The pointer wavered some passing the van, but otherwise remained solidly pointing due south for the entire length of the block, almost a hundred meters. When I got to the middle of the intersection, I turned around. The iPhone of course turned with me, and the pointer turned with it-- it did not hold it's geographic direction. As a result, when I had finished my 180-degree rotation, the pointer went the opposite way and was now correct. It remained fixed on north the entire return walk. Then I got the idea of hunting for a reliable source on how the thing works. This seemed reasonable: <http://www.slideshare.net/saldb/how-iphone-3g-s-compass-works-1639451> until the last page showed photos of the Dharma station Apple had built at the north pole to send out a radio signal for the compass to home in on. :-) There was another person besides me stating that the compass doesn't work in Usenet. Maybe we're not the only ones: <http://www.ilounge.com/index.php/backstage/comments/iphone-3gs-compass-flakiness-blame-the-hardware-or-the-os/> I found several folk talking about a problem in some iPhones making _both_ GPS and compass inaccurate, but in mine, the positioning is fine. -- Wes Groleau Women and men's pasts http://Ideas.Lang-Learn.us/barrett?itemid=1484
From: Salmon Egg on 3 Apr 2010 14:14 In article <hp6gnq$clm$1(a)news.eternal-september.org>, Wes Groleau <Groleau+news(a)FreeShell.org> wrote: > If a small piece of iron is placed near a magnetic compass, the needle > will point to the iron. <snip> How do you know that the compass in an iPhone is a magnetic compass? It may be getting its info from GPS. That cab be very wrong if you are not moving. Other than seeing an iPbone, I have no experience with it. Bill -- An old man would be better off never having been born.
From: Wes Groleau on 3 Apr 2010 14:27 On 04-03-2010 14:14, Salmon Egg wrote: > Wes Groleau<Groleau+news(a)FreeShell.org> wrote: >> If a small piece of iron is placed near a magnetic compass, the needle >> will point to the iron. > <snip> > > How do you know that the compass in an iPhone is a magnetic compass? It If you had read what you snipped, you'd realize that I know it ISN'T a magnetic compass. > may be getting its info from GPS. That cab be very wrong if you are not > moving. If you had the misfortune to join this subthread earlier, you'd realize that GPS/not moving was my initial hypothesis on why it doesn't work. I tried it again today in my car. It locked on pointing southwest instead of north as I drove a little over a mile. Moving/not moving isn't the answer. When I got out of the car, it claimed interference for about five seconds, then returned to pointing southwest. It continued to point southwest as I walked about twenty meters from the car to the restaurant. So interference from the metal in the car is not the full explanation either. No big deal. There are it least five other worse things about the iPhone, yet overall, I do not regret buying it. -- Wes Groleau Angry disruption in class http://Ideas.Lang-Learn.us/barrett?itemid=1455
From: Tim Adams on 3 Apr 2010 17:56 In article <hp81b3$shu$1(a)news.eternal-september.org>, Wes Groleau <Groleau+news(a)FreeShell.org> wrote: > On 04-03-2010 14:14, Salmon Egg wrote: > > Wes Groleau<Groleau+news(a)FreeShell.org> wrote: > >> If a small piece of iron is placed near a magnetic compass, the needle > >> will point to the iron. > > <snip> > > > > How do you know that the compass in an iPhone is a magnetic compass? It > > If you had read what you snipped, you'd realize that I know it ISN'T > a magnetic compass. > > > may be getting its info from GPS. That cab be very wrong if you are not > > moving. > > If you had the misfortune to join this subthread earlier, you'd realize > that GPS/not moving was my initial hypothesis on why it doesn't work. > > I tried it again today in my car. It locked on pointing southwest > instead of north as I drove a little over a mile. Moving/not moving > isn't the answer. When I got out of the car, it claimed interference > for about five seconds, then returned to pointing southwest. > > It continued to point southwest as I walked about twenty meters from the > car to the restaurant. So interference from the metal in the car > is not the full explanation either. > > No big deal. There are it least five other worse things about the > iPhone, yet overall, I do not regret buying it. Wes - are you talking about the Compass app that came with the iPhone 3gs or one of the add on compass applications that are available in the app's store? I ask because I have never had the stock application claim interference, ask for my location, or not work as well as a stand along compass in my home or out and about hiking in the woods. I do have a copy of the program CompassApp and it does many of things you speak of, but it's just a crappy app from what I can see, and I do not keep it loaded on my iPhone. Tim -- regarding Snit "You are not flamed because you speak the truth, you are flamed because you are a hideous troll and keep disrupting the newsgroup." Andrew J. Brehm
From: Wes Groleau on 3 Apr 2010 18:26 On 04-03-2010 17:56, Tim Adams wrote: > Wes - are you talking about the Compass app that came with the iPhone 3gs or one > of the add on compass applications that are available in the app's store? Yes. New in the 3GS. From what little I've read on the web, it seems that it works great for some people, but others see behavior like I'm seeing. -- Wes Groleau You be the judge http://Ideas.Lang-Learn.us/WWW?itemid=463
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