Lally Singh lally.singh at
Fri Jun 6 02:11:22 CEST 2008

On Thu, Jun 5, 2008 at 7:25 PM, Joerg Reisenweber <joerg at> 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: 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

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