Simon Willison’s Weblog

GPSJam (via) John Wiseman’s “Daily maps of GPS interference” —a beautiful interactive globe (powered by Mapbox GL) which you can use to see points of heaviest GPS interference over a 24 hour period, using data collected from commercial airline radios by ADS-B Exchange. “From what I can tell the most common reason for aircraft GPS systems to have degraded accuracy is jamming by military systems. At least, the vast majority of aircraft that I see with bad GPS accuracy are flying near conflict zones where GPS jamming is known to occur.” # 30th July 2022, 7:51 pm

How John Wiseman tracks worldwide GPS interference (via) Part of the ADS-B signals broadcast by commercial aircraft include a measure of GPS accuracy. By collecting global data every day, John is able to generate a map of areas that are experiencing higher than expected GPS interference, which generally corresponds to military jamming technology. He sometimes posts the resulting maps on Twitter—he just picked up increasing jamming activity around Moscow. # 20th July 2022, 11:45 pm

OSM the default map in Haiti. A search and rescue team member in Haiti sends word that digital maps constructed by the OpenStreetMap community are spreading by word of mouth and being loaded on to GPS units on the ground. # 25th January 2010, 9:26 pm

GPS and Relativity (via) GPS satellite clock ticks need an accuracy of 20-30 nanoseconds. The satellites move fast enough that their clocks fall behind by 7 microseconds a day due to time dilation, but orbit high enough that the curvature of spacetime due to the Earth’s mass puts them forward by another 45 microseconds. GPS receivers have to perform relativistic calculations to determine their location! # 11th January 2010, 9:17 am

Augmenting photos—with OSM! “You climbed up a mountain and took a photo ... but it’s 2009! Why doesn’t it have all kind of magic over the top of it.”—Marmota matches your landscape photos to height field data, then overlays data from OpenStreetMap mapped to the contours of the photograph. # 9th June 2009, 11:34 am

Tracking your Cat with GPS. Alex Lee strapped a GPS to his cat. # 6th October 2008, 9:16 pm

New A-GPS service for Nokia phones. Appears to look up your cell ID against a global database to find nearby satellites, dramatically reducing the time needed to get a GPS fix. # 6th August 2007, 11:26 pm

Talking to the internal GPS in my N95 from Python. Thanks to a new LocationRequestor module for Python Series 60. # 6th June 2007, 10:31 am

Mapping the postal network. Image of a GPS trace for a unit that was left on and sent in the post. # 20th December 2006, 12:43 am

Holux GPSlim (GR-236) Review. Matt Biddulph has one of these. They’re awesome. # 7th July 2006, 1:56 pm