GPS module - advice needed

[flotulopex]

Your right mackrackit,

But this cart is only used outside.

BTW, the cart has already an "electonic" speed indicator (looks like a cheap gadget).

The sensor's output must be an open-collector type contact (I might be wrong).

I tried to capture the signal in parallel with the sensor but I must do wrong an the only result I get is to make the signal crash completely (no speed is indicated anymore). I use an OpAmp for this but there is surely a better way...

[mackrackit]

What kind of cart is it? Maybe someone here has some info on it.

Outside yes. But outside there are things like power lines, buildings, mountains...Lots of things to get in the way of the signal.