GPS <--> AGPS

[Lally Singh]

On Thu, Jun 5, 2008 at 7:25 PM, Joerg Reisenweber <joerg at openmoko.org> wrote:
> Am Do  5. Juni 2008 schrieb Lally Singh:
>> AFAIK, the AGPS allows you to upload additional information into the
>> onboard correlator (the CPU that does the actual location calculations
>> for GPS) to enhance the accuracy over what you get with simple
>> satellite triangulation.
>
> It's about reducing TTFF, not increasing accuracy [1]. Basically you tell the
> receiver which sats it should expect, so it doesn't have to check all
> possible "channels" and "download" the data from sat (AFAIK). See ephem and
> alm in uBlox paper.
>
> [1] Increasing accuracy is differential-GPS, where you have a reference
> receiver at known position, so you can tell pos of 2nd relative to ref in
> sub-meter accuracy.
>
> Also see: http://wiki.openmoko.org/wiki/Hardware:AGPS which I found just after
> typing the above.

Ah, my mistake.  I was hoping for more than just an almanac/ephem
upload.  I'm a lot less excited now.

-- 
H. Lally Singh
Ph.D. Candidate, Computer Science
Virginia Tech