Missouri has a network of free GPS reference stations for centimeter location accuracy that I am wanting to use for a mower. There is one in north st. louis county that is close enough to me to be usable. I have gotten a log in to their network and can get some information but trying to get corrections in the NTRIP application of RTKLIB just times out. Has anyone used this or could help me with this.
Also, are there others that are interested in a mowers discussion?
I recently bought some “CHEEP” GPS receivers that I found on Amazon for about $10. They have a USB connector, and I was hoping that I could pull the NMEA messages off of the USB/COM port with a serial terminal emulator, or a VB application. I have been reading up a lot about GPS. I DO NOT RECOMEND BUYING CHEEP $10 GPS MODULES FROM AMAZON. They come with NO documentation, and no one seems to have windows drivers available for them.
I’d be VERY interested in hearing more about the GPS ground stations. What kind of receiver do you need? Any special frequency? Where can I learn more about this?
I figured out I have to provide my location in the request for data to get a valid response. Apparently that is used to select the closest reference station. I appear to be getting glonass data now but for some reason not gps.
This is reference station data available over the internet. You still need a GPS receiver and one that can measure timing of the reception from the satellites. This allows compensation for timing errors through the atmosphere and various other errors. Ublox F9P chip is one that can do it. Sparkfun has boards with it for about $220. A decent dual band antenna bumps that up to about $300. But using the correction data from the internet saves having to set up a second unit as a reference station. You also need a wireless link to get the data from the internet source to the rover.
https://gpsweb3.modot.mo.gov/
https://www.sparkfun.com/products/16481
The cheep GPS receivers that I bought say that they contain a UBLOX chip, however, I believe that it is a “Chinese copy” . I did manage to find some free software for reading GPS chips, and it works with these. The software also came with drivers, so I was able to build my own VB app to read the chip.
My whole robot uses “home brew” VB code, so that I can integrate the location data into all of the other apps. The Latitude and Longitude that the GPS chips report, matches (fairly close) to what my cell phone and google maps says is my home location.
[ but not down to the centimeter 
]
The software (for windows) is called “U-Center”