Global Positioning System

Poster showing how GPS works
Surveillance

How GPS Works

October 4, 2019 covertadmin Comments Off on How GPS Works

GPS is a constellation of 24 or more satellites flying 20,350 km above the surface of the Earth. Each one circles the planet twice a day in one of six orbits to provide continuous, worldwide coverage. 1. GPS satellites broadcast radio signals providing their locations, status, and precise time (t1) from on-board atomic clocks. 2. The GPS radio signals travel through space at the speed of light (c), more than 299,792 km/second. 3. A GPS device receives the radio signals, noting their exact time of arrival (t2), and uses these to calculate its distance from each satellite in view. To calculate its distance from a satellite, a GPS device applies this formula to the satellite’s signal: distance = rate x time, where rate is (c) and time is how long the signal traveled through space. The signal’s travel time is the difference between the time broadcast by the satellite (t1) and the time the signal is received (t2). 4. Once a GPS device knows its distance from at least four satellites, it can use geometry to determine its location on [Read More…]

A handheld GPS receiver
Surveillance

GPS Spoofing

February 5, 2021 covertadmin Comments Off on GPS Spoofing

The Global Positioning System (or GPS) is a satellite navigation system that uses satellites to provide autonomous geo-spatial positioning. This technology is everywhere – it’s in your car, your smartphone, your watch, your fitness tracker, handheld GPS receivers, and more. But did you know that these satellite signals can be jammed – or even worse – deceived using something called GPS spoofing? Let’s take a look at this interesting topic of discussion. What we’re going to review here applies to any of the popular satnav systems – that includes GPS (the US satnav), Galileo GNSS (or Galileo Global Navigation Satellite System – the European version), and Russia’s GLONASS system. How does GPS work? There are multiple GPS satellites in orbit around the earth. Special chips can be included in nearly any electronic device that can read signals transmitted from the satellites. And combined with a bit of math – the device can determine your position with great accuracy as long as it can receive signals from at least 4 of the satellites overhead. Sound expensive? Yep – it is. (At [Read More…]