GPS Spoofing - a satellite pretender

The increased reliance of many everyday activities on GPS technology, and recently the increased use of drones for military and other purposes, are raising the issue of the reliability and accuracy of the GPS signals.

This is not only valid for civilian applications, but now more and more for the electric power industry as well. The requirements for accurate time synchronization by Phasor Measurement Units (PMU) and IEC 61850 Merging Units (MU) demonstrate the increasing dependence of our industry on GPS.

In one of the recent issues of PAC World we talked briefly about the impact of solar storms on the availability of GPS signals. However, the capture of a military drone aircraft in 2011 and the speculations that it was the result of GPS spoofing forces us to look at what are the threats for the protection and control systems and applications that are based on precise time synchronization.


In general terms, Spoofing is a broad-ranging term that essentially means to pretend to be something or someone that you're not.

A GPS spoofing attack is exactly that - a device pretending to be a GPS satellite in an attempt to deceive a GPS receiver. 

It achieves that by broadcasting a slightly more powerful signal than that received from the GPS satellites, structured to resemble a set of normal GPS signals. Depending on the goals of the attack, the spoofed signals are modified in such a way as to cause the receiver to determine its position to be somewhere other than where it actually is, and more important, a location specifically determined by the attacker.

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