To understand the reason for blackouts, you need to know the basics of GPS navigation. You might have experienced your GPS device not working at some particular locations. But, when you change the location, it starts working again (although it takes some time to restart). The major reason behind this is that the GNSS satellites send in the information in form of radio signals.
Radio signals do not have powerful penetration strength. This means that the radio signals sent by GNSS satellites are not able to get through any concrete building, a solid Iron Gate, deep tunnels, or sometimes even in the elevator. This is why your GPS device cannot receive the signals when any obstruction comes between the satellite and the GPS device. These obstructions can be either in space (objects in space like rocks, dust clouds, and other similar obstacles), in Earth’s atmosphere (mostly dust particles and flying objects including airplanes), and, finally, on the surface (skyscrapers, monuments, or anything else that stops the signal from moving ahead).
In addition, the radio signals lose strength as they travel. Although the GNSS sends radio signals strong enough to reach your device, they have to pass through the vacuum (space) and different layers of Earth’s atmosphere. Depending upon your location, the GNSS signals may fade out. For example, if you are deep inside the ocean, you may find low strength signals that may make it difficult for the receiver inside your GPS machine to receive them, and your GPS device therefore shows you nothing.
Even with the above mentioned problems, GPS are being used for a variety of purposes: location, navigation, mapping, tracking, and timing. Other than the normal people; the military, mining, shuttles, and many more sectors are shifting their operations to GPS-based devices. The following section shows why GPS is so successful even with the lingering possibility of GPS Satellite Blackout.
Tip: It is always better to check the type of receiver inside your GPS device. A cheap receiver will give you more problems than a powerful GNSS receiver.