GPS soft baseband processing
Al Johnson
openmoko at mazikeen.demon.co.uk
Sun Sep 7 12:19:44 CEST 2008
On Sunday 07 September 2008, Andy Green wrote:
> Somebody in the thread at some point said:
> | On 9/7/08, Flemming Richter Mikkelsen <quatrox at gmail.com> wrote:
> |> "Our automatic geotagging technology solves these
> |> problems. A fragment of RAW GPS RF data is captured
> |> in 0.2 seconds and then stored alongside the digital image
> |> and the processing is performed later on a PC. Because
> |> we separate the GPS capture from the GPS processing,
> |> our technology maintains the traditional "instamatic" user
> |> experience we are all used to and then pulls consumers
> |> to experience a far more interesting way to search and
> |> share photographs later."
> |
> | Interesting.
> | Around 1995 I used about the same technique to sync spectrometer
> | data to an external authoritative timesource ( in that case the DCF77
> | signal encoded into 10ms dataframes ) time recovery could achieve
> | better than 100us
>
> It sounds like a fine technique, but it pushes the whole issue into
> license of the host CPU software then. They don't seem to mention if
> they provide it or it is liberally licensed, etc.
There appear to be several open source GPS projects around, including a few
that do correlation in software.
http://sourceforge.net/project/showfiles.php?group_id=91538&package_id=271229
http://gnuradio.org/trac/wiki/GlobalPositioningSystem
http://gnuradio.org/trac/wiki/GlobalNavigationSatelliteSystem
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