distance between two Espruinos with GPS (about 30m)

My first idee to connect two puck.js wasn't the best. So I decided to get two espruino WiFi with a Ubox Neo M8N GPS Module. So i determine the coordinates send them over Wi-fi and compare it to the other coordinates. So i can get a exact distance between them.

Is this plan possible?

i hope the Wifi will connect over a distance of 30 m, outdoors.

which WiFi is stromger, the WiFi from the Espruino WIFI or a original with ESP8266 ESP 12 Module ?

Does this post provide some insight http://forum.espruino.com/comments/13622029/

Could you elaborate on how much of an 'exact distance' you are expecting to achieve?

I Don't want a exact GPS Position, only a distance between them. I hope i can get a accuracy of 2 m.

You are asking a lot... Yes, GPSs are pretty accurate... but you may need multiple readings and that takes some time... moving things around 'quickly' will not give you much time to have a series of values from the same spot. 30m is already quite a distance for a plain Wifi, and with +/-2m GPS accuracy, this will give you for 30m +/-7%. On a distance of 15m, this then becomes +/-14% (roughly). I do not know what you want to do nor the exact circumstances, such as: do you have line of sight? What are the obstacles? Do you have free sky access? - but that is not a very efficient way to measure distance.

A while back I did some GPS stuff - DIY Marine GPS using enhanced GPS Module, u-blox NEO-6M GPS receiver, and ILI9341 Module controlled 2.8" Color TFT LCD. As you can see from the attached pics, I validated the setup in the car, and made also some comparisons what Google map would tell me about where I was with my device. I can not exactly remember the GPS accuracy, but I think it was not down to 2m.

I found the accuracy to the more like +/- 10m but this was with cheap copies of the neo-m8 off ebay but I did get some really good results (+/- 1m) using the same gps modules with rtklib.

I can't speak to the real accuracy of GPS but I think the Ublox modules are pretty good as long as you give them time to get a bunch of satellites.

The Espruino WiFi uses the ESP12 module as well, and I've tried to keep the PCB area around the aerial pretty clear so you should get about the same range off of that.

As before though, I can't really give you any accurate range figures - you'd just have to do some testing. I think WiFi does tend to use much higher signal strengths though so it should be much better.