"Jack Erbes" wrote in message
...
I'm a little confused about this. There are numerous explanations of
the NMEA sentences on the net, examples are Peter Bennet and Glenn
Baddeley's web sites:

http://vancouver-webpages.com/peter/nmeafaq.txt
http://home.mira.net/~gnb/gps/nmea.html

Those seem to contain most or all the NMEA 0183 information that anyone
would want. If you paid NMEA's sort of costly membership fee and
acquired their not too cheap specs, what more would be gained by doing
that?

Those sites contain only a part of the existing NMEA sentences and are
pre-V3.0. So if you can live with this info, no problem. But if you want to
develop software that gets the most out of modern equipment, it would be
wise the have the latest version available. For instance, on the sites you
mention, none of the descriptions of the GPRMC sentence show you the mode
indicator field which tells you if the fix is valid or not.

The standard expands as new equipment comes on the market. A nice example is
AIS. This required the definition of a whole new set of sentences, covered
from V3.0 and upwards.

Do you have to be a NMEA member to use the standard in firmware? Or
software?

No. Anyone can buy the standard from NMEA. But members get a discount.

Meindert