the prickhouse security website would be far more impressive if:

1- there were fewer typos on the page
2- they were not making claim to tracking down to 5 meters inside a building. I have a gps receiver working on all 52 channels and anyone who knows anything about gps can tell you it will not work accurately inside a building. In fact most manufacturers state that canopy cover in a forest or the human body can interfere with the signal. It has nothing to do with the receivers, it is the signal used by the sats.