… Because they [satellite positioning systems] rely on signals from satellites transmitting from an altitude of around 20,000 kilometres (12,400 miles), the signals are very weak, making them vulnerable to accidental or deliberate interference. This can take the form of natural interference, as a result of solar activity, for example; accidental man-made interference due to signal reflection or faulty transmitter equipment; and deliberate jamming of the satellite signal by transmitters that drown it out by broadcasting their own signal on the same frequency.

British police began finding jamming equipment in the possession of criminals about three years ago. This was not surprising, because evidence from satnavs and vehicle-tracking devices had already been used in several successful prosecutions. In July 2010 two men were jailed for a total of 16 years after they admitted being members of a gang that stole 40 lorries and their loads with a total value of £6m ($9.6m). They had used GPS jammers to prevent the vehicles being tracked after the thefts. In Germany, meanwhile, some lorry drivers have used jammers to evade the country’s GPS-based road-tolling system.

“If you do an internet search on GPS jammers, you get over 300,000 hits, with many of these linking to sites offering them for sale,” says Jim Hammond of the intelligent transport systems working group at Britain’s Association of Chief Police Officers (ACPO). “I’d suggest you don’t get that level of hits for products that nobody buys.” ACPO and Britain’s communications regulator, Ofcom, are urging the government to make it easier to prosecute people who use and sell jammers, and to make their possession a criminal act.

Geografias do Mar - Projeto de videoinstalação “Geografias do Mar # Travessia”

Geografias do Mar # Travessia é uma videoinstalação composta por vídeos produzidos a partir da Travessia Mar Grande-Salvador e de imagens-satélite. A obra aborda as experimentações do mar vivenciadas por nadadores, barqueiros e tripulantes de pequenas embarcações.

Três monitores dispostos lado a lado exibem diferentes vídeos. O primeiro apresenta a navegação através da rota de GPS gerada pela equipe de filmagem no dia da Travessia Mar Grande-Salvador. O áudio deste vídeo foi elaborado a partir de entrevistas realizadas com os maratonistas neste mesmo dia, após a competição. O segundo monitor exibe três vídeos com imagens gravadas durante o percurso da travessia, com captura de som ambiente e/ou trilha sonora. Já o terceiro monitor mostra imagens de simulação da variação de calor no Oceano Atlântico

Crisis Mappers from around the world have been working around the clock to create maps and other tools for relief workers in Haiti. The earthquake caused tremendous damage to the road network and updated maps are necessary to enable food and volunteers to traverse the island.

The volunteer-driven Open Street Map project has become a central data source for the Crisis Mappers. It is regarded by many as the most up-to-date map of the area. It combines UN damage assessment, digitized imagery, Public Domain Topos and other base data. In the wake of the tragedy Google quickly released Haiti data gathered from its MapMaker programDigitalGlobe has made itssatellite imagery of Haiti freely available as well (as did GeoEye).

Shortly there will be a free iPhone app with maps of Haiti coming to the App Store. Andrew Johnson and Jeffrey Johnson (no relation) have adapted an existing iPhone app (www.gaiagps.com) to provide offline maps to for relief workers. It combines Digital Globe (1m resolution), GeoEye (.5m resolution updated on 1/13), and OpenStreetMap (constantly being updated).

This version of Gaia GPS is intended to aid disaster relief for the Haitian earthquake. The app can be used to download maps and satellite imagery of the earthquake area, including up-to-date overlays of disaster sites, hospitals, and other relevant waypoints. The map data is provided by Digital Globe, GeoEye, OpenStreetMap, and the maps are hosted by the New York Public Library. 

The app also provides other features that might be relevant to disaster relief efforts: 

1) Recording of GPS tracks, waypoints, and geo-tagged photos 
2) Import/export GPX tracks and photos 
3) Guidance to waypoints and along tracks.

Walking the Edit

Walking the Edit

Under the media, the city

Equipped with an iPhone that records your trajectory with the help of a GPS, you hear along the way the soundtrack of the film that you are walking … As you progress, media previously placed in the territory are called up into your film: the form of the trajectory becomes the form of the film. Once the walk is complete, you can find your film on an internet site, choose to share it with the other users and watch their films.

This website is still under developpment: only 20% of the functionnalities are implemented - it gives only a “mechanical” idea of the potential of the concept.

The movies that are presented do not match our minimal expectation:

- there is no overlapping of the choosen media over the recorded trajectory
- there is no relation between the recorded speed and the lenght of the media
- there is no thematic continuation.

We hope that we can correct those bugs and recalculate the movies according to our artistic expectations.

Prácticas cartográficas: de los oligopolios a los sistemas abiertos

Siguiendo con el artículo sobre GPS hackers,

En la práctica cartográfica digital, tanto en los mapas como en el software de análisis (los GIS, sistemas de información geográfica, y programas similares) se han creado monopolios u oligopolios (en el software el monopolio de ESRI con ArcGis; en los mapas los oligopolios de Nokia y TomTom). El resultado son acceso restringido (por coste y limitaciones legales y de formatos), costes muy elevados y usos restringidos a expertos asociados a instituciones y empresas.

La combinación de iniciativas abiertas de comunidades de usuarios (en mapas OpenStreetMap; en software algunos proyectos de software libre, aunque en este caso su impacto ha sido mucho más limitado) y de empresas (Google con Maps y Earth o Garmin dejando que sus gadgets funcionen con OpenStreetMap) han permitido la popularización de las prácticas cartográficas (desde el uso de mapas digitales, GPS y software para navegación a la creación de cartografías ciudadanas), el abaratamiento radical de estas herramientas y la mejora de la calidad de los sistemas.

Los oligopolios basados en sistemas cerrados han provocado una geografía convencional ligada a los intereses de las instituciones que controlan los datos y herramientas. Los sistemas abiertos han permitido el desarrollo de una cartografía ciudadana y de una geografía experimental que critica las visiones convencionales e inmovilistas y permite la creatividad en el análisis y la resolución de problemas.

GPS Hackers Blaze Own Trails With Crowdsourced Maps | Gadget Lab | Wired.com
… The key to these map hacks is OpenStreetMap. Founded in 2004, OSM is to maps what Wikipedia is to encyclopedias. The site offers maps that can be edited, customized and loaded on to devices for free. Want to go whitewater rafting but need to know where the rapids are? There’s a map for that. Or to know all the interesting points along the river Nile? There’s a map for that. And it’s all based on the OpenStreetMap data…
Getting OpenStreetMap is easier on some devices than others. In Garmin systems, it’s as simple as taking one of the available maps and dropping it into a folder on the device …

GPS Hackers Blaze Own Trails With Crowdsourced Maps | Gadget Lab | Wired.com

… The key to these map hacks is OpenStreetMap. Founded in 2004, OSM is to maps what Wikipedia is to encyclopedias. The site offers maps that can be edited, customized and loaded on to devices for free. Want to go whitewater rafting but need to know where the rapids are? There’s a map for that. Or to know all the interesting points along the river Nile? There’s a map for that. And it’s all based on the OpenStreetMap data…

Getting OpenStreetMap is easier on some devices than others. In Garmin systems, it’s as simple as taking one of the available maps and dropping it into a folder on the device …