Date: Sat, 6 May 2000 10:07:30 -0600 (MDT) From: Nate Williams <nate@yogotech.com> To: Wes Peters <wes@softweyr.com> Cc: Poul-Henning Kamp <phk@critter.freebsd.dk>, Warner Losh <imp@village.org>, hackers@FreeBSD.ORG Subject: Re: GPS heads up Message-ID: <200005061607.KAA17627@nomad.yogotech.com> In-Reply-To: <3913BD91.1803945E@softweyr.com> References: <6827.957594577@critter.freebsd.dk> <3913BD91.1803945E@softweyr.com>
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> > >: With 12-channel chipsets becoming common, new devices are getting quite > > >: good at this. > > > > > >Yes. Most of the data I have is for 6 channel models. > > > > 12-chanel chipsets are overkill if you don't live more or les exactly > > on the equator or one of the poles. Here where I live (56 north) about > > 30% of the sky is never covered by a satelite because of the inclination > > of the satelites being non-zero. > > Get used to them, both Garmin and Trimble are using 12-channel engines > now. Even the cheapo Rockwell chipset is 6 channels, going to 12 by > the time the start putting them into mobile phones next year. There's > a mandate in the USA that all mobile phones have GPS in them by 2003, Actually, the phones don't have to have GPS, but they must be able to get a fix on them good to 100m. I talked to one of the engineers at Qualcomm last year who is working on this, and GPS isn't going to be used because it doesn't work in buildings. And, most of the world's cell-phones are used in buildings. They are doing triangulation and putting GPS units in the cell towers instead, which is far cheaper. Plus, they can get a fix on the phone in 300ms (good to about 25m), which is far faster than a GPS unit can do it. Basically, the phone is 'locked on' as soon as you turn it on and it finds a cell tower. And, apparently they've figured out a way to get a coarse fix on it even where there is only one tower, although when I pressured him, he just smiled and claimed it was a trade secret. Or so I've been told, but I trust the source since he's one of the smartest guys I ever met. :) Nate To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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