2019-11-30

More fun with GPS...

The NMEA sentences from a GPS work on degrees, minutes and fractions. As a format they are horrid - the sign is a separate character N/S, E/W, and the value is fixed length so DDMM.mmmm and DDDMM.mmmm format.

The 4 places for minutes is not that precise, but more than enough for absolute GPS positioning.

But there is an alternative, and it is like the IPv6 of GPS. More precision that you could ever want - ECEF format is X/Y/Z in metres from centre of the Earth to the micrometer!!!

$ECEFPOSVEL,124015.000,3985352.629186,-54462.755461,4962832.255023,-0.008022,0.003776,0.022063

Amazing. So whilst not adding absolute accuracy, it does add some impressive relative precision.


Walking in the road to spell my name, LOL.

5 comments:

  1. Have you tried comparing the accuracy while using the differential GPS method?
    i.e have one unit at a static fixed location and apply it's location error as a fix to the mobile unit.

    ReplyDelete
  2. Oooh I now have to create an ECEF Geocaching puzzle.

    ReplyDelete
  3. I quite agree with you about the horrible NMEA lat/long format, but it's not the case that NMEA limits the precision. There can be as many decimal places as the talker wants to include - it's your GPS which is limiting what you see.

    ReplyDelete

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