91–100 of 243 posts
I saw some rumblings (can't find an article) that there's interest in restarting LORAN to provide an alternative to GPS for this reason.
The Wikipedia page says that China has deployed an eLoran network but I can't tell if used for navigation or just high-precision timing.
Earlier quoted context omitted.
Celestial navigation requires an accurate clock and an almanac that needs to be updated. It is completely impractical for non-military applications.
Is that really that impractical? With a quick calculation 50 ms time offset would mean about 20 meter difference. You can get that accuracy with NTP over residential internet and a better TCXO could hold that for a day. You could sync clocks and download the almanac at each airport. The almanac could be digitally signed and NTP has an option for authentication, too. That's about 10 USD of hardware (plus what you need…
[0] https://www.righto.com/2026/04/B-52-star-tracker-angle-compu...
Earlier quoted context omitted.
That's near orders of magnitude more than reality. The only number that matters is the number of satellites that are in communication line of site. A satellite on the other side of the world doesn't help you.
I wonder how many are in view? gps is 31 total satellites 12,000 miles up starlink is 10,000 satellites at ~ 300 miles. (and what orbit?) EDIT: I found this: -- starlink: "In any given place there are 3-4 Starlink satellites visible at a time" https://news.ycombinator.com/item?id=42445512 :) in december 2024, there were 4,000 starlink satellites in orbit so starlink is ~ 8 at all times? -- GPS: This 24-slot arrangeme…
Our RTK base station (a Ublox ZED-F9P receiver, with a cheap patch antenna on the roof) can currently see 45 GNSS satellites.
I wish there were cheap Bluetooth jammers to prevent speakers from playing when hiking
Earlier quoted context omitted.
I'm not going to argue that as it's always easy to blame dead people, but there's two different types of jamming. One is to actually jam the signal IOW preventing reception. The other is to overpower the satellites' signals and replace them with your own. That defeats the doppler calculations of GPS needed for triangulation, and instead the receiver believes it's where the jammer wants it to be. If the latter include…
I believe it’s been made public that this was a jamming test, not a spoofing test.
If you can say, "oh we were only jamming" when in fact you were spoofing, well that's certainly a super easy excuse to hide behind.
Starlink can be uses as GPS. Good luck jamming 20 thousand satellites.
Secondly, the number of satellites doesn’t really matter, the jamming happens at the end user level not at the satellite.
Finally, where are you getting that 20k number from? It’s not like there’s 20k starlink satellites in LOS to your station at all times. The earth will be obscuring many of those, they are below your feet on the other side of the planet.
Whats really sad for aviation is there was already an extensive network of ground based navaids. As GPS has proliferated, they've slowly been decommissioned as they age out to save on cost. I'm specifically referring to VORs which provide azimuth and range to station. GPS is fantastic and as a primary source everyone loves the benefits it brings. However, in a century of aviation, everyone has kinda sorted out that y…
All VORs provide a radial that you’re on. Not all provide a distance to the station. VOR/DME or VORTACs provide both. Plain VORs do not. As more and more are decommissioned, the percentage that support distance-measuring goes up, as the ones being decommissioned are more likely to be the less-useful ones, which are less likely to have supported DME in the first place. So most remaining ones support both, but it’s not…