[tw1984]

> GPS signals are much higher frequency and very low power and thus don’t work indoors.

With a $20 antenna placed near the window, together with a modern receiver, it is easy to get nanosecond level of precision for GPS systems. Some receivers even have in-door precision specification.

GPS not only work indoors, in terms of timing, it works actually pretty well indoors.

[2rsf]

Why would I need that for? nanosecond accuracy? GPS indoors?

[tw1984]

e.g. to get yourself a stable frequency standard that can be used in all kinds of electronics projects & equipments.