Garmin sat nav

[Frances IoMParticipant @francesiom58905]

many 1st gen sat navs keep a fairly detailed record of last journeys made – this can be uploaded if for example you connect to a PC (these days only with your consent tho in past I think such consent was implied when you operated the device)

[Ady1Participant @ady1]

Someone has finally pointed out that there is a big gorilla in the corner of the room

What happens to British ships when satellites don't work?

My answer would be a laser sextant for use at night

Point it at the star, self levelling bubble horizon, self contained clock, push a button, tell it which star you just read, get a position line in 10 seconds.

Edited By Ady1 on 28/07/2021 10:12:17

[John HaineParticipant @johnhaine32865]

Download Camsextant from app store. Don't even need to know which star. Why would you need a laser? Ships took sights at night for centuries without one?

[Ady1Participant @ady1]

okay

[John HaineParticipant @johnhaine32865]

Posted by Ady1 on 28/07/2021 10:07:39:

Someone has finally pointed out that there is a big gorilla in the corner of the room

What happens to British ships when satellites don't work?

My answer would be a laser sextant for use at night

Point it at the star, self levelling bubble horizon, self contained clock, push a button, tell it which star you just read, get a position line in 10 seconds.

Edited By Ady1 on 28/07/2021 10:12:17

Just to add to my reply, inertial navigation systems are used already for marine navigation and give a continuous real-time estimate of position with no external reference. Semi-automatic sextants exist that can take a sight on a star, and you can get a reasonable fix from a single star sight if you have the right almanac data, it's bearing, and accurate time (which can come from a low cost atomic clock). Though GNSS signals can be jammed and spoofed there are countermeasures, and given there are 4 global systems in operation, put up by the USA, EU, Russia and China, it's unlikely that all 4 would be unavailable at the same time – and multi-standard receivers are common. I think marine navigation would find it inconvenient if GNSS disappeared but it could be survived. The loss of time synchronisation on land-based cellular networks and financial transaction systems would be much more of a worry I think.

And that BBC report is awful, confuses GPS positioning with satellite communications, confuses Loran-C that uses low HF bands with cellular phones that use uhf and microwave bands.

If you think it's just foreign states that jam GPS this makes interesting reading.

Edited By John Haine on 28/07/2021 16:59:24

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