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Knowing the "Now" of Our Earth Through GNSS

Software engineer John Wiseman of Los Angeles, USA has created the "Daily maps of GPS interference" on GPSJam. As this labeling implies, the maps published here show day-to-day interference activities to GNSS on a global scale. Many forms of GPS interference exist; Wiseman's maps show instances of "jamming," which is achieved through large-scale output of interfering waves.
GPSJam divides the earth's surface into hexagonal cells roughly the size as Sado Island in Niigata Prefecture, Japan, (which is 855 square kilometers / 330 square miles in size), and color-codes each cell in one of three colors to indicate reduced GPS positioning precision. Information is updated once per day based on Coordinated Universal Time (UTC), and past data can be viewed as far back as February 14, 2022.
The system utilizes Automatic Dependent Surveillance–Broadcast (ADS-B) signals emitted by aircraft in order to estimate interference levels. These standard-based signals are broadcast by each aircraft individually to communicate information such as identification number, position and speed, which facilitates safer and more efficient aircraft operations. ADS-B signals can be received by anyone who has the proper equipment.
As a relatively familiar example to many readers, Flightradar24, ADS-B Exchange and AirNav RadarBox are some aircraft tracking websites that collect ADS-B signal data from all over the world and visualize them.
ADS-B signal data has a parameter called "integrity," which refers to the reliability and precision of its positioning information, and GPSJam utilizes this parameter as an index for estimating jamming levels and creating its maps.

The Devious Approach of Spoofing—Or "Impersonation"

Jamming, which is a primitive and heavy-handed method, targets broadcasters and other telecommunications services. When it comes to GNSS, however, a more devious approach exists: spoofing, which is a kind of "signal impersonation."
Generally speaking, information on GNSS signals, which is based on civil specifications, is open to public, meaning it is possible to generate fake GNSS signal which people expect to receive at a certain place and time. However, this is much more difficult than jamming, as positioning calculations in the receiver system use signals from multiple satellites. Therefore, spoofing can only be accomplished if the spoofer has sufficiently sophisticated software and computer and broadcasting equipment that enables to generate consistent signal with the real GNSS system.
Additionally, anti-spoofing measures are employed by signal receivers, algorithms that detects multiple frequencies and discrepancies are becoming more sophisticated, and research and deployment of directional antennas are progressing. Generally speaking, spoofers work almost the same way as GNSS signal simulators, utilized for development and assessment of receiver, meaning that the more sophisticated the simulators become, the greater the potential of anti-interference measures in receivers.
Wiseman is currently developing an algorithm for future implementation in GPSJam to estimate signal transmission sources for purposes of identifying spoofing occurrences (through means such as detection of sudden position hopping and so forth). However, he explains, "Unless there are more planes in the air, it will be impossible to find the interfering waves."

The Possibility of Visualizing Peace on Thematic Globes

GPSJam's default start position is centered on Ukraine. The nation, which declared independence in 1991 under its yellow-and-blue flag, displays no green, yellow or red cells on the site's map; rather, there is a marked absence of data altogether. No ADS-B signal emitting planes are flying through Ukrainian airspace at the moment, meaning no data is available on which to base estimates. If one turns back the clock to around February 24, 2022 or so, when the conflict between Russia and Ukraine broke out, it's easy to see the process of data block disappearance as aircraft signals drop out.
As of the end of 2023, yellow and red cells indicating signal interference can be observed in the area extending from western Russia to the three Baltic states, in the region stretching from Turkey to Israel, near the India–Pakistan border, near the border between the United States and Mexico, and in certain other locations. It's easy to spot the problems with GNSS interference in Europe by viewing these maps.
Interference detection measures, which represent the first major countermeasures needed in such a situation, have already been deployed to a significant degree using existing equipment and on a global scale, which is quite impressive when you think about it. It's unlikely that red and yellow cells will all turn green again at the snap of a finger amid the ongoing crises in the abovementioned areas, and there is no telling when data-absent regions will receive coverage again. This thematic globe provide informations about warfare and conflict risk through GNSS signal interference. I hope this will be an indicator that shows where peace prevails and are kept as green areas. At least, that's my simple and somewhat sentimental view.