3 ms·

I'm curious to know why resurrecting (e)Loran seems to be a hard sell: * https://en.wikipedia.org/wiki/Loran-C https://en.wikipedia.org/wiki/Loran-C China bui

I'm curious to know why resurrecting (e)Loran seems to be a hard sell: * https://en.wikipedia.org/wiki/Loran-C https://en.wikipedia.org/wiki/Loran-C China built out a GNSS backup with it: * https://www.gpsworld.com/china-completes-national-eloran-network/ https://www.gpsworld.com/china-completes-national-eloran-net... * https://rntfnd.org/2024/10/03/china-completes-national-eloran-network-the-paper/ https://rntfnd.org/2024/10/03/china-completes-national-elora... * https://www.mdpi.com/2076-3417/13/23/12703 https://www.mdpi.com/2076-3417/13/23/12703 And there's been some rumblings from Korea and UK: * https://www.gpsworld.com/south-korea-partners-with-broadcaster-on-eloran-and-10-cm-gps/ https://www.gpsworld.com/south-korea-partners-with-broadcast... * https://www.gpsworld.com/uk-leading-the-west-in-pnt-with-clocks-eloran-and-quantum-research/ https://www.gpsworld.com/uk-leading-the-west-in-pnt-with-clo... but no major moves in most countries, even though there's a recognition of GPS/GNSS vulnerabilities by even the (US) military: * https://fedtechmagazine.com/article/2022/05/dod-transportation-consider-backups-vulnerable-gps https://fedtechmagazine.com/article/2022/05/dod-transportati...

sorenjan 1y ago
There's BPS (Broadcast Positioning System) too. https://www.nab.org/bps/ https://www.nab.org/bps/
relaxing 1y ago
Because despite what they say the signals can still be jammed. Also your transmitters are massive targets for kinetic fires.
- throw0101d 1y ago
  Of course any signal can be jammed if you throw enough watts out, but Loran is five millions times stronger: * https://www.militaryaerospace.com/rf-analog/article/14181490/eloran-loran-c-gps-gnss https://www.militaryaerospace.com/rf-analog/article/14181490... And even if your ground transmitters can be taken out, it's a lot easier to build some new Loran transmission gear and radio towers than it is to launch new GNSS satellites (which are also vulnerable to attack).
  - relaxing 1y ago
    I realize that probably sounds insurmountable, but the practical upshot of that factoid is you can jam GPS with a handheld transmitter. Military jammers can be much, much bigger. As big as a 5,000,000x Loran transmitter even! I think in reality, it’s easier to put little star trackers on your boats and planes. And it’s way easier to launch another cruise missile at the rebuilt LORAN site.
    - throw0101d 1y ago
      > Military jammers can be much, much bigger. As big as a 5,000,000x Loran transmitter even! Which can become a target themselves. > I think in reality, it’s easier to put little star trackers on your boats and planes. The star tracker in this article is €250K: that may be 'affordable' for a plane manufacturer or a >5000 TEU cargo ship, but perhaps less so for smaller commercial and recreational boats. Meanwhile a survey of Loran-C receivers published in 1984 had some units available down to the USD 2000 range: * https://rosap.ntl.bts.gov/view/dot/11795/dot_11795_DS1.pdf https://rosap.ntl.bts.gov/view/dot/11795/dot_11795_DS1.pdf I would think that the development of electronics over the intervening decades would allow for units to be much cheaper now. A (touch-screen) chart plotter with built-in GPS is available for as little as USD 800: * https://www.westmarine.com/multifunction-displays-combos/?srule=Price_Low_To_High https://www.westmarine.com/multifunction-displays-combos/?sr... Compare its capabilities to a (LCD screen) Loran-C receiver from 1990: * https://sarmarine.com/product/raymarine-raynav-780-loran-c-receiver/ https://sarmarine.com/product/raymarine-raynav-780-loran-c-r... * https://www.manualslib.com/manual/313978/Raymarine-Raynav-780.html?page=125#manual https://www.manualslib.com/manual/313978/Raymarine-Raynav-78... At the end of the day, it's probably more about both-and and not either-or. The more you want to reduce risk, the more independent systems you want to use to tie together to create a better model of reality with regards to where your location "is". And if you don't want to rely on electronics at all, then you can also get a mechanical watch and a sextant, which was done even on aircraft: * https://www.youtube.com/watch?v=xc3rAlCDf54 https://www.youtube.com/watch?v=xc3rAlCDf54 * https://www.youtube.com/watch?v=C7gAiI79nOY https://www.youtube.com/watch?v=C7gAiI79nOY

sorenjan 1y ago

There's BPS (Broadcast Positioning System) too. https://www.nab.org/bps/ https://www.nab.org/bps/

relaxing 1y ago

Because despite what they say the signals can still be jammed. Also your transmitters are massive targets for kinetic fires.

throw0101d 1y ago
Of course any signal can be jammed if you throw enough watts out, but Loran is five millions times stronger: * https://www.militaryaerospace.com/rf-analog/article/14181490/eloran-loran-c-gps-gnss https://www.militaryaerospace.com/rf-analog/article/14181490... And even if your ground transmitters can be taken out, it's a lot easier to build some new Loran transmission gear and radio towers than it is to launch new GNSS satellites (which are also vulnerable to attack).
- relaxing 1y ago
  I realize that probably sounds insurmountable, but the practical upshot of that factoid is you can jam GPS with a handheld transmitter. Military jammers can be much, much bigger. As big as a 5,000,000x Loran transmitter even! I think in reality, it’s easier to put little star trackers on your boats and planes. And it’s way easier to launch another cruise missile at the rebuilt LORAN site.
  - throw0101d 1y ago
    > Military jammers can be much, much bigger. As big as a 5,000,000x Loran transmitter even! Which can become a target themselves. > I think in reality, it’s easier to put little star trackers on your boats and planes. The star tracker in this article is €250K: that may be 'affordable' for a plane manufacturer or a >5000 TEU cargo ship, but perhaps less so for smaller commercial and recreational boats. Meanwhile a survey of Loran-C receivers published in 1984 had some units available down to the USD 2000 range: * https://rosap.ntl.bts.gov/view/dot/11795/dot_11795_DS1.pdf https://rosap.ntl.bts.gov/view/dot/11795/dot_11795_DS1.pdf I would think that the development of electronics over the intervening decades would allow for units to be much cheaper now. A (touch-screen) chart plotter with built-in GPS is available for as little as USD 800: * https://www.westmarine.com/multifunction-displays-combos/?srule=Price_Low_To_High https://www.westmarine.com/multifunction-displays-combos/?sr... Compare its capabilities to a (LCD screen) Loran-C receiver from 1990: * https://sarmarine.com/product/raymarine-raynav-780-loran-c-receiver/ https://sarmarine.com/product/raymarine-raynav-780-loran-c-r... * https://www.manualslib.com/manual/313978/Raymarine-Raynav-780.html?page=125#manual https://www.manualslib.com/manual/313978/Raymarine-Raynav-78... At the end of the day, it's probably more about both-and and not either-or. The more you want to reduce risk, the more independent systems you want to use to tie together to create a better model of reality with regards to where your location "is". And if you don't want to rely on electronics at all, then you can also get a mechanical watch and a sextant, which was done even on aircraft: * https://www.youtube.com/watch?v=xc3rAlCDf54 https://www.youtube.com/watch?v=xc3rAlCDf54 * https://www.youtube.com/watch?v=C7gAiI79nOY https://www.youtube.com/watch?v=C7gAiI79nOY