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Ultimate GPS track values very erratic
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Ultimate GPS track values very erratic

by just_croaker on Mon Aug 02, 2021 10:14 pm

I'm kind of new to a lot of this, but I'm an old IT guy and wanted to play a bit. I hooked up an Ultimate GPS Breakout to a Pi 4. It's connected with the USB to TTL Serial cable you recommend in your tutorial. I found some Python code and everything seemed to be working fine, but the code was only outputting latitude and longitude. I modified the code to output track data, and the values I'm seeing vary widely. I let it run for an hour, nothing changed. I attached an external active antenna, no change. I took it outside, no change. The values I'm seeing are valid values for compass heading, but swing plus or minus 60 degrees or more. Any clues??

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Re: Ultimate GPS track values very erratic

by adafruit_support_bill on Tue Aug 03, 2021 5:40 am

GPS does not measure heading directly. It calculates it from the recent history of changes in location. Since standard GPS resolution is on the order of meters, and noise in the system can result in random small changes in location, heading values for stationary or slowly moving units will be erratic.

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