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jrd22 · 03-03-2010, 09:28

It might be a good time to start reviewing dead reckoning, set and drift, etc. This article from the BBC makes it sound like it's a question of when, not if, the GPS system will be hacked or disabled.

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"Sat-nav systems under growing threat from 'jammers'

By Jason Palmer
Science and technology reporter, BBC News

"Society will only get ever more dependent on sat-nav systems

"Technology that depends on satellite-navigation signals is increasingly threatened by attack from widely available equipment, experts say.

"While 'jamming' sat-nav equipment with noise signals is on the rise, more sophisticated methods allow hackers even to program what receivers display.
At risk are not only sat-nav users, but also critical national infrastructure. "

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To read the entire article, go to:

http://news.bbc.co.uk/2/hi/science/nature/8533157.stm

Red Mantis · 03-03-2010, 09:40

Next thing you know, BBC will have an article about how a substance called "rum" is messing with the accuracy of our eyeballs, and how shady purveyors of this substance tend to set up shop around marinas.

Is nothing safe any more?

fishwife · 03-03-2010, 12:39

Technology that depends on satellite-navigation signals is increasingly threatened by attack from widely available equipment, experts say.

Full story here BBC News - Sat-nav systems under growing threat from 'jammers'

P.

Hiracer · 03-03-2010, 12:43

"Each satellite in a sat-nav constellation is putting out less power than a car headlight, illuminating more than a third of the Earth's surface at a distance of more than 20,000 km."

"What that means, and what has brought this group of policy-makers, academics and industry figures together, is that the signals can be easily swamped by equipment back on Earth."

Interesting stuff.

bastonjock · 03-03-2010, 13:22

I use a sat nav based tracker system in my 20 ton truck,i can see the apeal to criminals who would want to jam the tracker system in order to steal the goods being carried.This would also apply to a great many other things such as Armoured trucks etc

I cant see these jamming devices working way out in the north sea etc,but what if you use it to jam the GPS signals at the entrance to a buisy shipping port? that could cause mayhem

its all back to the electronics versus the paper charts argument

Viking Sailor · 03-03-2010, 20:12

Although the GPS signals are very weak they are very resistant to jamming. In fact all of the satellites transmit on the same frequency without interfering with each other. The technique used is know as spread-spectrum coding. Each of the satellite signals are bi-phase modulated using one of 64 "Gold" codes. These codes are unique in that they do not interfere with each other. Additionally, the navigational information transmitted by the satellite is formatted in a way that it must match information transmitted by the other satellites.

The GPS receiver must match the code used by the satellite in order to receive the its signal. This matching process make the satellites signal stronger and any interfering signal weaker. Further, if the received signal is not correctly formatted and does not have the correct navigational information is will be ignored. It also takes a minimum of 3 satellites before the receiver will even try to compute a fix.

These characteristics make it nearly impossible to spoof or jam the GPS system. I am aware of only two ways to disable the system short of blowing something up. These involve the use of a signal on the GPS frequency that is so strong that it desensitize the receiver, or the transmission of a very strong random noise signal that buries the GPS signal. Both of these methods are very local and targeted. They are not useful over a wide area. Also, receiver will detect these forms of jamming and warn the operator.