Contrib: Adjusting map position after base station change (#28)

When changing a base station or adjusting the base station, the map position is wrong. In this article i show how to fix that

content/en/docs/contributions/basestation/_index.md

@@ -0,0 +1,32 @@
+---
+title: Adjusting map position after a basestation change
+linkTitle: Basestation location change
+description: >
+  Sometimes you have to change the location of the NTRIP base station or you change to another NTRIP provider. In that
+  case your map will probably shift position and you cannot use the mower anymore because it will not be accurate when
+  mowing.
+---
+
+
+When you use the OM_DATUM_LAT and OM_DATUM_LONG DATUM fields in the mower_config.txt, you can shift the map around.
+
+The procedure if you change the NTRIP base, is to change the DATUM Fields (`OM_DATUM_LAT` for the left and right,
+`OM_DATUM_LONG` for up and down) in the mower_config.txt file. What you basically do when you change the DATUM fields is
+shift the complete map up/down/left/right.
+
+In order to position the map aligned with a fixed point on the map, you can use the docking position of the mower. To do
+this properly, you have to undock the mower via the area recording buttons, drive a little bit around for an accurate
+positioning of the mower and then dock the mower manually using the area recording buttons.
+
+After docking, you see in the web interface that the mower is a bit off the docking position. You adjust the position of
+the map just a bit. To move the map horizontally, you adjust the `OM_DATUM_LAT` a bit and to move the map vertically,
+adjust the `OM_DATUM_LONG`.  (The precision is depending on your position on the globe, but the 7th digit will give you
+about 1cm movement per digit). If you move the map down, the position of the mower will go up on the map and vise versa.
+
+Remember to reload the exports (the easy way is a reboot of the pi if you are patient and lazy) and then drive around
+again a bit via the area recording buttons and dock manually again. In that way, you have a constant correct location
+when adjusting the map position. When you think it is all good, then go ahead, start mowing and let the mower return to
+docking immediately to see if the docking works precisely and the mower docks automatically and properly.
+
+Then start mowing, the mower will do the outline first (normally 4 rounds, check the 4th round very thoroughly, that is
+the round closest to the edge). If all is ok, you are good to go.