4 ms·

And LORAN. But it may make a come-back. GPS signals are just incredibly weak so it takes next to nothing to drown them out, easier still if you are above the r

And LORAN. But it may make a come-back. GPS signals are just incredibly weak so it takes next to nothing to drown them out, easier still if you are above the receiver.

toomuchtodo 1mo ago
I would be curious on and interested in guidance from a GNSS expert on what the risk profile is when you're using jam resistant frequencies with a multi GNSS constellation chipset (GPS, Galileo, BeiDou), WAAS (GNSS corrections received via satellite), and when close enough to airports that support it, LAAS (GNSS corrections broadcast from airports). Follow up questions would be what countermeasures are available to bolster GNSS reliability during critical phases of flight (takeoff and landing), as well as how cellular tower networks could be used as distributed sensor fabrics for constantly monitoring for and triangulate GNSS jamming using SDR (or perhaps start with a handful of GNSS reference monitoring stations at major airports for this monitoring). https://news.ycombinator.com/item?id=49186101 https://news.ycombinator.com/item?id=49186101 https://news.ycombinator.com/item?id=49184484 https://news.ycombinator.com/item?id=49184484 GPSJam: Daily maps of possible GPS interference - https://news.ycombinator.com/item?id=37868106 https://news.ycombinator.com/item?id=37868106 - October 2023 (89 comments) GPSJam: Daily Maps of GPS Interference - https://news.ycombinator.com/item?id=32245346 https://news.ycombinator.com/item?id=32245346 - July 2022 (82 comments) https://en.wikipedia.org/wiki/Transmitter_hunting https://en.wikipedia.org/wiki/Transmitter_hunting | https://en.wikipedia.org/wiki/Pseudo-range_multilateration https://en.wikipedia.org/wiki/Pseudo-range_multilateration | https://www.arrl.org/direction-finding https://www.arrl.org/direction-finding https://geodesy.noaa.gov/CORS/ https://geodesy.noaa.gov/CORS/ | https://arcg.is/18fWq8 https://arcg.is/18fWq8
- leonidasrup 1mo ago
  Because GPS and other GNSS have only a very weak signal strength there are no jam resistant frequencies, you can jam them all very efficiently, or you can jam them very efficiently in selective way (jam BeiDou, but not GPS). GPS was jammed even as early as Iraq war. "Coalition troops also got a glimpse of GPS’s greatest weakness during the Gulf War. Iraqi forces installed jammers, for example, on top of landmarks such as Saddam Hussein’s palaces to prevent them from being hit, Mastalir says. This helped the military realize early on that it would have to further develop its laser-guided munitions and other weapons that acquire targets when GPS is unavailable" https://web.archive.org/web/20160208233555/http://www.scientificamerican.com/article/gps-and-the-world-s-first-space-war/ https://web.archive.org/web/20160208233555/http://www.scient...
  - jacquesm 1mo ago
    A lot of work is being done to make GPS more jam resistant, and - just as important - more spoof resistant. The latest batch of satellites has a whole raft of countermeasures to help a receiver to identify whether the received signal is genuine or whether it was spoofed. Receivers too can do a lot to detect spoofing by just observing the signal (for instance: unrealistic power levels on reception, impossible response to vehicle movement and others besides), but quite a few of those are unrealistic or too expensive for regular (non military) applications. Jam resistant frequencies do not exist as you already mentioned, from a physics perspective. But GP might mean this to refer to the new M-Code signal, and these are sent out on different frequency offsets from the main carrier, so effectively different frequencies.
    - leonidasrup 1mo ago
      Jam resistance and spoof resistantance are very different. What work is done to make GPS more jam resistant?
      - toomuchtodo 1mo ago
        https://gps.stanford.edu/research/current-and-continuing-gpspnt-research/cyber-safety-transportation/jamming-resitance https://gps.stanford.edu/research/current-and-continuing-gps... Single element antennas, adaptive antennas, beam steering antennas. Basically attempting to pull good RF while avoiding bad RF. (this has been applied in the Russo-Ukrainian war in modified Starlink equipment) GPS antenna mods make Starlink terminal immune to jammers - https://news.ycombinator.com/item?id=39616417 https://news.ycombinator.com/item?id=39616417 - March 2024 (72 comments) https://olegkutkov.me/2023/11/07/connecting-external-gps-antenna-to-the-starlink-terminal/ https://olegkutkov.me/2023/11/07/connecting-external-gps-ant...
        dingaling 1mo ago
        The Russian response to directional antennas is to mount GPS jammers on satellites https://www.gpsworld.com/todd-humphreys-russian-satellites-a-cause-of-gnss-jamming-across-europe/ https://www.gpsworld.com/todd-humphreys-russian-satellites-a...

And LORAN. But it may make a come-back. GPS signals are just incredibly weak so it takes next to nothing to drown them out, easier still if you are above the receiver.

toomuchtodo 1mo ago

I would be curious on and interested in guidance from a GNSS expert on what the risk profile is when you're using jam resistant frequencies with a multi GNSS constellation chipset (GPS, Galileo, BeiDou), WAAS (GNSS corrections received via satellite), and when close enough to airports that support it, LAAS (GNSS corrections broadcast from airports). Follow up questions would be what countermeasures are available to bolster GNSS reliability during critical phases of flight (takeoff and landing), as well as how cellular tower networks could be used as distributed sensor fabrics for constantly monitoring for and triangulate GNSS jamming using SDR (or perhaps start with a handful of GNSS reference monitoring stations at major airports for this monitoring). https://news.ycombinator.com/item?id=49186101 https://news.ycombinator.com/item?id=49186101 https://news.ycombinator.com/item?id=49184484 https://news.ycombinator.com/item?id=49184484 GPSJam: Daily maps of possible GPS interference - https://news.ycombinator.com/item?id=37868106 https://news.ycombinator.com/item?id=37868106 - October 2023 (89 comments) GPSJam: Daily Maps of GPS Interference - https://news.ycombinator.com/item?id=32245346 https://news.ycombinator.com/item?id=32245346 - July 2022 (82 comments) https://en.wikipedia.org/wiki/Transmitter_hunting https://en.wikipedia.org/wiki/Transmitter_hunting | https://en.wikipedia.org/wiki/Pseudo-range_multilateration https://en.wikipedia.org/wiki/Pseudo-range_multilateration | https://www.arrl.org/direction-finding https://www.arrl.org/direction-finding https://geodesy.noaa.gov/CORS/ https://geodesy.noaa.gov/CORS/ | https://arcg.is/18fWq8 https://arcg.is/18fWq8

leonidasrup 1mo ago
Because GPS and other GNSS have only a very weak signal strength there are no jam resistant frequencies, you can jam them all very efficiently, or you can jam them very efficiently in selective way (jam BeiDou, but not GPS). GPS was jammed even as early as Iraq war. "Coalition troops also got a glimpse of GPS’s greatest weakness during the Gulf War. Iraqi forces installed jammers, for example, on top of landmarks such as Saddam Hussein’s palaces to prevent them from being hit, Mastalir says. This helped the military realize early on that it would have to further develop its laser-guided munitions and other weapons that acquire targets when GPS is unavailable" https://web.archive.org/web/20160208233555/http://www.scientificamerican.com/article/gps-and-the-world-s-first-space-war/ https://web.archive.org/web/20160208233555/http://www.scient...
- jacquesm 1mo ago
  A lot of work is being done to make GPS more jam resistant, and - just as important - more spoof resistant. The latest batch of satellites has a whole raft of countermeasures to help a receiver to identify whether the received signal is genuine or whether it was spoofed. Receivers too can do a lot to detect spoofing by just observing the signal (for instance: unrealistic power levels on reception, impossible response to vehicle movement and others besides), but quite a few of those are unrealistic or too expensive for regular (non military) applications. Jam resistant frequencies do not exist as you already mentioned, from a physics perspective. But GP might mean this to refer to the new M-Code signal, and these are sent out on different frequency offsets from the main carrier, so effectively different frequencies.
  - leonidasrup 1mo ago
    Jam resistance and spoof resistantance are very different. What work is done to make GPS more jam resistant?
    - toomuchtodo 1mo ago
      https://gps.stanford.edu/research/current-and-continuing-gpspnt-research/cyber-safety-transportation/jamming-resitance https://gps.stanford.edu/research/current-and-continuing-gps... Single element antennas, adaptive antennas, beam steering antennas. Basically attempting to pull good RF while avoiding bad RF. (this has been applied in the Russo-Ukrainian war in modified Starlink equipment) GPS antenna mods make Starlink terminal immune to jammers - https://news.ycombinator.com/item?id=39616417 https://news.ycombinator.com/item?id=39616417 - March 2024 (72 comments) https://olegkutkov.me/2023/11/07/connecting-external-gps-antenna-to-the-starlink-terminal/ https://olegkutkov.me/2023/11/07/connecting-external-gps-ant...
      - dingaling 1mo ago
        The Russian response to directional antennas is to mount GPS jammers on satellites https://www.gpsworld.com/todd-humphreys-russian-satellites-a-cause-of-gnss-jamming-across-europe/ https://www.gpsworld.com/todd-humphreys-russian-satellites-a...