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Militart "accidently" jams GPS signals


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Obviously I spelled "Military" wrong. :huh:


Hmmm, an accident or a test?


Jamming Incident


JNC Briefing on Jamming Incident


Why do we need a backup? Here is a classic case in point.


At the JNC in Orlando, we heard from U.S. Coast Guard Captain Matthew Blizard, the commander of the USCG Center of Excellence for Navigation (NAVCEN), including GPS. Captain Blizard detailed a case study that should be a wake-up call for all GPS users and help point out the criticality of augmentations and back-ups for our ubiquitous global utility that we all too often take for granted (GPS World editor-in-chief Alan Cameron briefly mentioned this incident in the March issue).


The quick version of the incident, which is full of irony, goes something like this. The U.S. Navy was conducting a scheduled communications jamming training exercise in the Port of San Diego. Two Navy ships participated in the exercise for approximately two hours. Although it involved communications jamming, GPS agencies such as the GPS Operations Center at Schriever AFB, Colorado (GPSOC) and the USCG NAVCEN were not notified because the intended jamming was not planned in the GPS L-band regime. But jam GPS they did — unintentionally of course — and the jamming continued for approximately two hours.


When the technicians involved could not get their GPS on the second ship (the one being jammed) to initialize, they began to suspect there might be a problem. They suspected ‘they’ were the problem and were inadvertently jamming GPS. They immediately returned to the first ship and shut down the jammer.


However, once the jamming began, it was less than 30 minutes before NAVCEN and the GPSOC and other organizations started receiving calls concerning GPS outages in the San Diego harbor area. The outages affected telephone switches and cellular phone operations and even shut down a hospital’s mobile paging system. General aviation GPS navigation equipment outages were reported, but no commercial airlines were affected, or at least none officially reported any outages. Reports continued to flow in for more than four hours.


The Navy technicians shut down the unintentional jamming signal, but did not report the incident outside of normal channels. Consequently, it took NAVCEN and supporting agencies 72 hours to pinpoint the jamming source.


The irony here is that the SPAWAR Systems Center for the GPS JPO (now GPS Wing) NAVWAR effort is located in San Diego and they routinely run jamming scenarios, simulations, and engage in modeling exactly what happened that day in the San Diego harbor — but reports indicate they were unaware of this incident until after it had occurred.


Captain Blizard accepts that 72 hours to locate a jamming source, intentional or otherwise, is entirely too long. He and his NAVCEN team are working with the GPSOC, the Joint Space Operations Center (JSPOC) at Vandenberg AFB in California, and other agencies to put procedures in place to effectively shrink the timeline to find the source of the jamming to 20 minutes or less. All these players want to ensure that in the future, these incidents are so short-lived that users will not even notice them before they are resolved.


There are lots of lessons learned here, and too many to go into in the space remaining, but this incident clearly emphasizes the vulnerability of our extremely low-power GPS signal to jamming and unintentional interference. It is also clear that we are not yet equipped nor have sufficient procedures in place to pinpoint jamming in a timely manner and take actions to negate it. However, it inspires confidence when you hear Captain Blizzard relate the incident, because you know he is working the solution hard. There was no attempted cover-up, it is all out in the open, warts, ironies and all, and it is clear that the solution is getting plenty of attention.

Edited by Crusso
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