[time-nuts] iGPS?

[DaveH]

Have you seen the orbit of the Sirius satellites? 

http://www.tiger-usa.com/satellite_animation.htm

Dave


> -----Original Message-----
> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf 
> Of Jim Lux
> Sent: Monday, May 18, 2015 21:52
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] iGPS?
> 
> On 5/18/15 7:59 PM, Chris Albertson wrote:
> > Yes GPS can do better than 50M but we are talking about a single fix
> > from a cell phone in a moving car not a survey receiver.  .  The
> > displayed location is better because the phone applies a 
> filter to the
> > location data.  Some thing like a Kalman filter.   I doubt 
> the iPhone
> > can get within 10M from a moving car.
> >
> > As for Iridium being an expensive for pay service.  But that is
> > because most users SEND data.  This new service is 
> broadcast and costs
> > do not depend on the number of users.   Apple has sold 130,000,000
> > phones already just in this half of 2015.  A one time 
> payment of about
> > $1 per phone might cover the costs.
> 
> Why iridium?  Why not Sirius or XM or DBS. Unless you want something 
> world wide, as opposed to "populated areas served by 
> broadcast radio and 
> TV"
> 
> Heck, you could probably buy transponder time on a C-band 
> satellite and 
> radiate a GPS assist signal (that's what WAAS is, after all)
> >
> >>> hmmmmm..I do believe the marketing boys have been playing with the
> >>> numbers. You would have to start
> >>> from a >50 M error to get them to make much sense based 
> on what they are
> >>> doing.
> >
> 
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