• 0 Posts
  • 8 Comments
Joined 1 year ago
cake
Cake day: June 25th, 2023

help-circle


  • I always thought the Mer de Glace at the Mont Blanc illustrates this really well. You arrive and there’s a sign “the glacier was here in 1910” and that’s where tourists back then.

    To get to the actual glacier, you have to eall down many flights of metal stairs for about half an hour and there’s several signs for different years, 1950, 1990, 2002, 2006, 2009, 2012, 2014, 2015, something like this, with the years between each sign getting shorter but the distance staying roughly the same. And from the top it’s really far away.

    Of course, once you actually reach the glacier, you get to the main attraction, a 3m diameter tunnel they bored 100m deep into it as a tourist attraction with ice sculptures inside. Above the tunnel you can see the remains of the tunnel from the previous year, half melted…






  • Just to add to this, because it’s fascinating. GPS satellites signals are about as strong as radiation from a light bulb, 20000km away. The signal that arrives on earth is 20db weaker than the noise floor, so background noise is a lot stronger than the signal is.

    The way it works is that the background noise is random and the signal is repeated many times a second, so you can split the signal and add it together. The random background noise averages out and you’re left with a strong signal. But due to this, it’s enough to have a very weak signal that adds non random noise on the correct frequency for it to just break.

    And actually what I desribed above is just the first layer of a GPS signal, it gets a lot more complicated with signals within signals, it’s pretty crazy how well it works. this is an amazing write uo on how the signal actually works, in case anyone is interested