GPS Interference from New Cell Service

Readers may remember that back in January there was a ‘mysterious’ report of expected GPS outages by the FAA that were re-broadcast by ICS-CERT because of their potential for interfering with certain timing signals used by some SCADA systems. I never did see a good explanation for the cause of the problem until early this morning when I was looking over the late news from yesterday.

An interesting article over on NextGov.com was discussing a test conducted by LightSquared, a new cell service provider, to see if their cell phone broadcasts interfered with GPS reception on nearby frequencies in areas near the cell towers. Low and behold, in a limited area right near the tower they completely scrambled some GPS receivers and just threw off the accuracy of other receivers. There is still some debate apparently whether the broadcast signal broadcast outside of the allowed spectrum, which borders the frequency allotted for GPS receivers; or if the receivers were too sensitive to signals outside of the allotted GPS spectrum.

I see no mention in this report of whether or not any SCADA devices were tested to see if LightSquared’s signal interfered with the GPS timing signal used by those devices to coordinate timing of actions at multiple, remote locations. From the scope of the tests reported in this article it would seem that the SCADA device would have to be close to the cell phone tower, but I know of two pipe line pumping stations near where I live that appear to have cell towers within the station perimeter.

I am absolutely sure (SARCASM Warning) that the ICS-CERT, PHMSA and TSA Pipeline Security have all been intimately involved in these studies, as have the appropriate vendors and anyone else with an interest at SCADA operations at remote locations. Everyone is too smart and communicates too well for something like this to have fallen through the cracks.