Is there a step by step process to convert sets of raw satellite data to traditional GPS lat/long points or a website that takes the data and processes it?

Example of the raw satellite data:


Have looked thru the following:




What is the approximate error of the Pythagorean Theorem vs. Haversine Formula in measuring distances on a sphere at various scales?

  • 1
    Welcome to GIS SE. As a new user, please take the Tour, which explains how our "Focused question / Best answer" model operates. We are not a tutorial site. In order to be answered, questions need to show an appropriate level of research, and an attempt to solve the problem. All questions should specify the GIS software in use. – Vince Jun 15 '18 at 4:00
  • What've looked at so far was taking the raw satellite data and trying to find how a GPS converts them to coords. How to calc: quora.com/… courses.psu.edu/aersp/aersp055_r81/satellites/gps_details.html I just haven't come up with the right "take these data elements from the satellite message and put it into this formula", etc. – David Levine Jun 15 '18 at 13:47
  • Please Edit the question to provide clarifications. It's not fair to those who would answer to need to sift through comments for critical information. – Vince Jun 15 '18 at 18:11

It looks like a NMEA message.

gpsworld.com has some details about how the NMEA messages are structured:

To understand the NMEA message structure, let’s examine the popular $GPGGA message. This particular message was output from an RTK GPS receiver:

$GPGGA,181908.00,3404.7041778,N,07044.3966270, W,4,13,1.00,495.144,M,29.200,M,0.10,0000*40

All NMEA messages start with the $ character, and each data field is separated by a comma.

GP represent that it is a GPS position (GL would denote GLONASS).

181908.00 is the time stamp: UTC time in hours, minutes and seconds.

3404.7041778 is the latitude in the DDMM.MMMMM format. Decimal places are variable.

N denotes north latitude.

07044.3966270 is the longitude in the DDDMM.MMMMM format. Decimal places are variable.

W denotes west longitude.


It goes on. But based on that info, I would say the time = 18:04:45.0811520511 UTC; latitude = 27° 1' N; longitude = 93° 49' W; and altitude = 20162.9 km.

That site also has an Excel workbook for converting the coordinates from DDDMM.MMMMM into other formats.

I'm not aware of any sites or software that process those NMEA strings (though there might be some). That said, armed with an understanding of the message components, there should be lots of ways to go about processing the data yourself.

One option would be to use Excel to separate the string into columns and then create formulas for the coordinate conversion based on that workbook.

  • Thanks. The lat/long/distance are what was received by the GPS from the satellite. They are not the lat/long position of the GPS but of the satellite location at the time the message was sent. Seems I can't ask a "tutorial" type question here so I'll close this out. Thanks for the response. – David Levine Jun 15 '18 at 13:42
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    @DavidLevine You're mistaken. They are the position of the GPS unit (more or less) that has been calculated by the GPS unit using at least 3 satellite signals. – mkennedy Jun 15 '18 at 15:20
  • @DavidLevine There are other NMEA sentences that contain the satellite positions. – mkennedy Jun 15 '18 at 15:28

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