Ultimate GPS Location Wrong

Breakout boards, sensors, other Adafruit kits, etc.

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
User avatar
littledan
 
Posts: 7
Joined: Thu Feb 27, 2014 3:05 pm

Ultimate GPS Location Wrong

Post by littledan »

I have finally had some time to connect up my Ultimate GPS V3 to my Arduino. Using the external antenna, I got a fix really quick and after about 30 seconds or so I fixed to about 10 satellites. Using the example sketches as well as parsing the NMEA sentences manually (which produces identical results), when I put the Lat and Long into Google Earth my "position" is about 30 miles south east of my actual position. Any help would be appreciated as accuracy is supposed to be within 1.8 meters.

User avatar
littledan
 
Posts: 7
Joined: Thu Feb 27, 2014 3:05 pm

Re: Ultimate GPS Location Wrong

Post by littledan »

Okay, so perhaps I am a little bit confused. I downloaded the GPS Tool for windows and that application picked up my location almost exact. I am obviously misunderstanding the data or at least the intention of the GPS Library Sketches. Let me rephrase my question: With the data that is extracted from the NMEA sentences or from Adafruit's parser, what do I need to do with that data in order to identify my position? Are there resources that I am overlooking that would aid in my understanding of how to interpret this data?

Thanks for your help in advance.

User avatar
adafruit_support_mike
 
Posts: 67446
Joined: Thu Feb 11, 2010 2:51 pm

Re: Ultimate GPS Location Wrong

Post by adafruit_support_mike »

There's a note about that in the tutorial.

The latitude and longitude values reported by the GPS module are degrees, minutes, and fractions of a minute. The first two digits after the decimal point will never take values outside the range 00-59. If you treat the number as a straight fraction of a degree, you get a fixed offset that depends on the size of your minutes-to-decimal error.

User avatar
littledan
 
Posts: 7
Joined: Thu Feb 27, 2014 3:05 pm

Re: Ultimate GPS Location Wrong

Post by littledan »

Mike,
I swear I read that thing a dozen times; it wasn't until your post that I actually comprehended it. Thanks for the reply.

User avatar
adafruit_support_mike
 
Posts: 67446
Joined: Thu Feb 11, 2010 2:51 pm

Re: Ultimate GPS Location Wrong

Post by adafruit_support_mike »

Been there..

Technology is full of details that are only obvious *after* someone else points them out. ;-)

Locked
Please be positive and constructive with your questions and comments.

Return to “Other Products from Adafruit”