61–70 of 86 posts
Earlier quoted context omitted.
The crypto for US military GPS uses the same keys worldwide, and rotated ~ weekly. That means if you capture any device which has the crypto keys, then you can spoof military GPS for the rest of the week, allowing you to do lots more damage. Therefore, the military often doesn't even use the keys in their own devices.
How do you know this?
I made this site. Copying a comment I made on HN a few weeks ago: The ADS-B signals that many aircraft broadcast include not just the aircraft's GPS positions, but also a measure of GPS accuracy (strictly speaking, ADS-B doesn't talk about GPS specifically and can handle any sort of navigation technology; I'm sure there are some planes out there reporting positions based on inertial navigation systems, with correspon…
> Kaliningrad in March 2022 I'm around there and my boat plotter (~2005 device) was going berserk in June! Will have to ask other boaters if they had similar experience? Also, how does ADS-B exchange get coverage around antarctic (i.e. Durban to Australia flights)? I thought they rely on RTL-SDR's sprinkled around the land? I know Iridium monitors ADS-B and AIS from space, but at this point they can also monitor jamm…
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> how do you measure your own gps “accuracy”? Because GPS is way cool. First, there is the official site: https://www.gps.gov/systems/gps/performance/accuracy/ I am far from being an expert, but being a flying nerd, that's what I can tell you: The more satellites in sight you have access to, the cooler stuff you can do with GPS. Minimum to establish 2D (on globe projection 2D) location is 3 sats, minimum for altitude…
Friend of mine is doing ocean bottom surveys. He uses pretty decent GPS receiver, but also gets real-time (or applies it later) "correction" data from ground based stations that calculate error caused by atmosphere, which gets him down to 1cm accuracy.
This is trying to measure ionosphere disturbances which affect signal propagation rates via ground reference stations. The real-time model is then calculated and distributed using ground stations and geostationary satellites.
GPS is way, way cool, and it's a pity the extent of its engineering is not better known.
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Id be fairly confident that they would. They also are encoded so that receivers that literally have no idea where they are can train on the received stream. Also don't forget that the receiver needs to hear signal from at least 3 or 4 satellites to be able to triangulate their position and altitude.
The wikipedia page has some info, looks like various CRC and parity checks. Maybe the receiver was just ignoring them, and receiving faulty data. I dunno, it seems to me like that GPS receiver had fairly bad software. If you get packets from a bunch of different satellites but one is way off, it seems like good sense to throw that one away.
Earlier quoted context omitted.
> Kaliningrad in March 2022 I'm around there and my boat plotter (~2005 device) was going berserk in June! Will have to ask other boaters if they had similar experience? Also, how does ADS-B exchange get coverage around antarctic (i.e. Durban to Australia flights)? I thought they rely on RTL-SDR's sprinkled around the land? I know Iridium monitors ADS-B and AIS from space, but at this point they can also monitor jamm…
https://flightaware.com/adsb/coverage/ shows an ADS-B receiver at McMurdo station and at least 2 others in Antarctica.
I made this site. Copying a comment I made on HN a few weeks ago: The ADS-B signals that many aircraft broadcast include not just the aircraft's GPS positions, but also a measure of GPS accuracy (strictly speaking, ADS-B doesn't talk about GPS specifically and can handle any sort of navigation technology; I'm sure there are some planes out there reporting positions based on inertial navigation systems, with correspon…
it seems obvious publishing this might not be fully appreciated by the crowd who jams. has this project generated any complaints?
Since nobody’s asked: How does GPS jamming work?
Basic jamming: Transmit a strong signal on the main GPS frequency (1575.42 MHz). Receivers get saturated and can't hear the real signal. Medium Jamming: Transmit the signal that a receiver would receive at a specific location loudly. GPS receivers will lock onto that signal, and report they are at the location you choose, rather than the real location they're at. Advanced Jamming: Pick a target, such as a VIP plane.…
It seems that progress is being made: https://insidegnss.com/what-is-navigation-message-authentica...
I made this site. Copying a comment I made on HN a few weeks ago: The ADS-B signals that many aircraft broadcast include not just the aircraft's GPS positions, but also a measure of GPS accuracy (strictly speaking, ADS-B doesn't talk about GPS specifically and can handle any sort of navigation technology; I'm sure there are some planes out there reporting positions based on inertial navigation systems, with correspon…
> I sometimes wonder if I would disrupt someone's nascent [systematic interference] business model if I started publishing my maps regularly. it seems obvious publishing this might not be fully appreciated by the crowd who jams. has this project generated any complaints?
Back before I made this site, when I was publishing my maps on twitter, on-demand, I did get DMs like "I'm Ukrainian. Could you make maps for [range of dates] for [region]?" and I had to think through the ethics. Was I OK publishing information that could not-inconceivably get someone killed in a war zone? Was that person really Ukrainian? Did it matter?
I decided that this information is being broadcast for anyone to easily receive, and also that it is self-censoring in a way: aircraft generally don't fly with ADS-B in a war zone, so I don't have data for hot war zones. (But I'm open to revisiting if someone has a different perspective.)
There was a spot I stood on in Japan probably 20 years ago that made my (handheld Garmin) GPS think I was traveling at something like 700mph at some angle across the globe. Once I left the area by maybe 10 feet, everything returned to normal. Went back to the spot, same thing. Always wondered what caused that.
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https://flightaware.com/adsb/coverage/ shows an ADS-B receiver at McMurdo station and at least 2 others in Antarctica.
Whats the range of it tho?
https://www.flightradar24.com/blog/tracking-flights-with-our...