Re: OT: Converting miles/km

 Ar an dara lá is fiche de mí Méan Fómhair, scríobh Peter Moylan:

 > On 22/09/24 16:59, Aidan Kehoe wrote:
 > > Ar an dara lá is fiche de mí Méan Fómhair, scríobh Hibou:
 >
 > >> I think you've missed my point, which was that the system for
 > >> determining the speed limit is thoroughly unreliable, and not a
 > >> suitable basis for restrictors, or even alarms sounding in drivers'
 > >> ears.
 > >
 > > Ah, maybe I have. My 2019 Toyota Corolla has a system that reads the
 > > speed-limit signs, displays the currently active speed limit, and
 > > changes the usual black-numbers-on-a-white-background display to
 > > white-numbers-on-a-red-background if I exceed that speed. It very
 > > occasionally gets things wrong but is usually reliable, even on those
 > > parts of the island afflicted by speed limits in MPH. So my reading
 > > of things is from my own relevant experience rather than a journalist
 > > driving clicks.
 >
 > My car, which is 14 years old, doesn't have such a feature. Despite that
 > my GPS navigator manages to display the speed limit, except in places
 > where reception from satellites is blocked. I assume that the limits are
 > contained in map data. Why then would the car need to read roadside signs?

I was working on the assumption that the car does not have a GPS receiver; it
has a SIM card and will call the emergency services if it feels there is an
accident, and my working understanding was that its location sensing was done
in the same way that mobile phones do, with triangulation from masts.

However I have no mobile reception where I live and when I check today it does
seem to work out the location with reasonable fidelity (I don’t normallly use
the built-in navigation, Toyota do not excel at software) so it may have a
built-in GPS.

 > OK, I'll concede that there are sometimes temporary limits in place
 > because of roadworks and so on, but that's the exceptional case.

It does pick up temporary speed limit signs that are unlikely to be in the map
data.

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