Unlike CDMA, GPS will not work inside buildings. To receive GPS signals the antenna must have a view of the sky. The best location is on a roof-top with the antenna in view of a maximum amount of sky. However, our GPS products have the ability to operate in a single-satellite mode. This lets you avoid the trouble and expense of a rooftop installation by allowing you to mount the antenna in a window of your building with only a partial view of the sky.