Thread: Theory about why GPS performs poorly
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jussik is offline jussik
2008-02-07 , 11:01
Posts: 139 | Thanked: 24 times | Joined on Sep 2005
#93
Originally Posted by ag2 View Post
Interesting. My B 1 is very different, but B 2 is mostly the same. Looks like B 1 may be the ephemeris and B 2 the almanac. Only problem is that 1153 bytes is not enough to hold the 15k bit message. Perhaps this is due to error correction overhead in GPS messages? Another possibility is that only the non-empty part of the almanac is stored.
I assume the data sets could have varying lengths (otherwise writing the length in the header would be weird). That's why I thought having a few examples would be interesting.

Am I missing something? Is there more to A-GPS than I imagine?
We'd still have to RE the data format and probably also the commands that are used to feed the data to the chip (unless gpsdriver does that somehow automatically, which I doubt).