ARLA/CLUSTER: Interferencias provocadas pelo Sol nos GPS´s

[João Costa > CT1FBF]

GPS: Solar Flares and Jamming

BBC Radio 4 describes how easy it is to jam GPS and that even solar
flares can affect the navigation system

Among those interviewed in the show is Professor Catherine Mitchell of
the University of Bath who describes the impact of Solar Flares on GPS
systems.

The BBC description of the show says:

We all rely on GPS - the Global Positioning System network of
satellites - whether we want to or not.

>From shipping to taxis to mobile phones, the goods we consume and the
technology with which we run our lives depend upon a low-power, weak
and vulnerable signal beamed from a few tonnes of electronics orbiting
above our heads.

This dependence is a new Achilles' heel for the world's financial,
commercial and military establishments. From North Korea's concerted
disruption of the South's maritime and airborne fleet, to white van
drivers' evading the boss's scrutiny over lunch, this signal is easy
to jam, with disastrous consequences.

Some people are looking at alternatives. Quentin Cooper meets the
scientists and engineers developing alternative, resilient, navigation
systems.

Listen online to the BBC show Finding a way: The future of navigation
http://www.bbc.co.uk/programmes/b038yq98

Just a few milliwatts from an oscillator in a high location can knock
out GPS out over a wide area. Research work is currently underway to
develop methods of jamming GPS in such a way that those affected are
not aware, e.g, no loss of GPS alarm, and making them believe they are
in a completely different location. Some pioneering work in this field
is being done by researchers at the University of Texas, see

GPS Spoofing experiment knocks ship off course
http://www.southgatearc.org/news/august2013/
gps_spoofing_experiment_knocks_ship_off_course.htm

Ofcom regularly announce details of Jamming Exercises being carried
out in the UK, see
http://stakeholders.ofcom.org.uk/spectrum/gps-jamming-exercises/

The Galileo GPS system under development may prove slightly harder to
jam using simple equipment. It will transmit a wideband signal across
bands of frequencies such as 1260-1300 MHz. This may prove to be more
robust that the US GPS, however, in an article Peter Blair G3LTF
suggests that some amateur radio transmissions in 1260-1300 MHz could
affect Galileo GPS receivers several kilometres away.

Read Peter G3LTF's article on Galileo at
http://www.southgatearc.org/articles/galileo.htm