GPS & USB Interface

I've got an RC car that has a Copernicus GPS on it. If I am at my computer looking at the GPS signals coming in everything works great. If I detach the USB cable and instead let it write to the SparkFun OpenLog the GPS rarely gets a signal lock.

I have checked the voltage levels on the GPS and they look normal in both cases (3.3V). I can't figure out why the GPS doesn't work the same in both cases. I don't have the receive tied to the transmit line on the GPS because I figured I only want to receive data.

Any ideas what might cause this?

Got a schematic?

Is the ground wire connected?


When you had the GPS connected to your computer, were you closer to a window or door? My GPS module only works near an open window in my building. Have you tried outdoors?