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[DPRG] Any recommendations on GPS Modules?

Subject: [DPRG] Any recommendations on GPS Modules?
From: Randy M. Dumse rmd at newmicros.com
Date: Mon Jul 2 20:12:05 CDT 2012

I haven't looked at the GPS modules much since we settled on the
EM-406 with SirF III. About 2--6 era. I could get GPS ina
basement and in a concrete parking garage. I was impressed. I
guess the SiRF IV are perhaps more incredible, came out last
fall as I recall. I haven't used one.
GPS modules are terrible for the most part. Almost all do 1
update per second and spit out 5 lines of NMEA standard junk at
4800 or 9600 baud. It's long, full of data you don't want. You
have to read two or three lines of it to get the few pieces you
want. Some lines have (trying to remember) 18 fields, comma
separated. It takes too much time and CPU power to do all the
parsing. Ridiculous, IMHO. 
Some more advanced units do 5 updatea a second. Too much data
too fast. You can dedicate a whole micro to reading and decoding
the information. Here's the really ridiculous part. The CPU in
the GPS has to be something like at least an ARM 7 to be fast
enough to run the GPS and encode all that crap in the format you
don't want. So you've probably got a more capable CPU in your
GPS than in the brain of your robot. Weird. And that advanced
CPU probably takes more current to run compared to your regular
micro. Unless you go PC type CPU. Then your power numbers are
wacked and you probably won't notice the GPS. 
I haven't found a reasonable proprietary format either. It would
be nice if you could just get it to spit out a fix in some
binary format. The proprietary format usually has seven or
eitght fields in it too. YMMV.
Good luck and erply if you find anything better than the mess I
am describing.


From: dprglist-bounces at dprg.org
[mailto:dprglist-bounces at dprg.org] On Behalf Of paradug
Sent: Friday, June 29, 2012 9:50 AM
To: dprglist
Subject: [DPRG] Any recommendations on GPS Modules?

Thinking towards Roborama2012B in November, I was wondering if
anyone had any recommendations for GPS modules? Cost, fast
coordinate acquisition rate, ease of use, antenna effectiveness,
and interface methods are aspects that I would expect to
influence the purchase selection decision. I am interested in
other folks experiences and suggestions.
 I have an Garmin foretrex and Garmin GPS 60 that I sometimes
use while hiking or geo-caching. Both units have data ports. I
was wondering if their antenna would be more effective than the
ceramic plate antenna that most modules have ( the foretrex
might have a ceramic plate antenna (?)). I suspect that their
coordinate acquisition rate is slow, but using one of these
might be the answer.  
Doug P.  

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