[time-nuts] iGPS?

Bob Camp kb8tq at n1k.org
Tue May 19 10:51:29 UTC 2015


Hi

The idea is that more sats in more directions = better fixes. The assumption
is that you are in an urban canyon. Most of the sky is blocked and you 
“need” sats in just the right part of the sky. There’s always going to be 
some configuration of buildings that *could* give you a problem.

Bob

> On May 19, 2015, at 12:52 AM, Jim Lux <jimlux at earthlink.net> wrote:
> 
> 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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