Cleaning GPS Telemetry

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Cleaning GPS Telemetry

Postby SpaceManMat » Mon Apr 08, 2019 7:28 pm

I've noticed data issues in my GPS telemetry data and I've also seen Google Earth incorrectly process them as well. So I came up with some VB scripting in Excel that will help clean up bad NMEA sentences.

Usage is pretty simple, in the Control worksheet enter the file location, name and extension. The complete file name is shown below along with the name of the clean version. Then press the Clean File button. The input file is then read and checked for valid NMEA sentences, all valid sentences are written to the NMEA worksheet along with the line number on which the sentence was originally located. The results are then written out to the new file.
GPS File Cleaner.jpg

You can compare the new file with the original using a text compare program such as Notepad++
GPS File Cleaner Compare.gif

The above example is typical of my GPS tracker under boost, you can see the following corrections:
Lines 181 and 186 where removed because they are not valid (some data lost mid sentence)
Lines 185 and 200 start with one sentence that was truncated with no end of line termination, the next sentence was then added to the same line. In this case the first partial sentence is discarded but the second sentence is kept as it is valid.
Line 199 is removed as the start of the sentence is missing.

Hope people found this helpful.
GPS File
(50.75 KiB) Downloaded 141 times
QRS: 124
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

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