when i check the GPS Values like speed, lat,lot and so on with a timer i get different values without moving the GPS mouse. Is it a problem of my mouse or is it a generell problem. How can i fix it?
You can check the raw data coming from the GPS.
Instead of passing Serial.InputString to the GPS object save it to a file or a multiline textbox and check the values.
The GPS library just parses the NMEA strings.