Re:75% of the world’s industrial fishing vessels are hidden ...
by defrost on Thursday January 04, 2024 @08:25PM
(#38874577)
> ADS-B data is broadcast every half-second on a 1090MHz, digital data link.
For more than a decade I worked airborne geophysical surveying - hundred thousand to a million+ line kilometre grid draping at 80m ground clearance on routes planned in advance.
The planes ran stable known instrument configurations and were calibrated weekly to measure their individual magnetic and radiometric signature.
Aircraft positioning signals on long haul flights Australia -> India -> Fiji -> Mali weren't an issue.
Extraneous non required signalling during grid surveying was an issue.
A reasonable comprimise was to blip a quick position fix at the end of every fourth or fifth 20 kilometre line run (say) ... otherwise no broadcasts during instrument recording times .. and glow in the dark divers watches for the pilots or random chunks of metal casing there one day and gone the next.
For more than a decade I worked airborne geophysical surveying - hundred thousand to a million+ line kilometre grid draping at 80m ground clearance on routes planned in advance.
The planes ran stable known instrument configurations and were calibrated weekly to measure their individual magnetic and radiometric signature.
Aircraft positioning signals on long haul flights Australia -> India -> Fiji -> Mali weren't an issue.
Extraneous non required signalling during grid surveying was an issue.
A reasonable comprimise was to blip a quick position fix at the end of every fourth or fifth 20 kilometre line run (say) ... otherwise no broadcasts during instrument recording times .. and glow in the dark divers watches for the pilots or random chunks of metal casing there one day and gone the next.