22 Matching Annotations
  1. Dec 2022
    1. An absolute location can be confidently calculated only when four (or more) distance values are available.
  2. Sep 2022
  3. arxiv.org arxiv.org
    1. G. Rizzi and M. L. Ruggiero, editors, Relativity in Rotating Frames, p. 167.Kluwer, Amsterdan, 2004,
      • BOOK, LOOK FOR
    2. J.-F. Pascual-S ́anchez, L. Flor ́ıa, A. San Miguel, and F. Vicente, editors, Reference Framesand Gravitomagnetism, p. 53. World Scientific, Singapore, 2001
      • LOOK FOR
    3. current GNSS: GPS and GLONASS. These systems are based on a Newtonian modelwhich is corrected numerically by important “relativistic effects”. This model uses the ECIand ECEF “Newtonian” reference frames, respectively for time reference and navigation


    4. et us define location systems as the physical realizations of some coordinate systems.Location systems are of two different types: reference systems and positioning systems.The first ones are 4-dimensional reference systems which allow one observer, consideredat the origin, to assign four coordinates to the events of his neighborhood by means of atransmission of information. Due to the finite speed of light this assignment is intrinsicallyretarded with a time delay. The second one are 4-dimensional positioning systems (as usedin the SYPOR) which allow to every event of a given domain to know its proper coordinateswithout delay or in an immediate or instantaneous way.In Relativity, a (retarded) reference system can be constructed starting from an (immedi-ate) positioning system (it is sufficient that each event sends its coordinates to the observerat the origin) but not the other way around. In contrast, in Newtonian theory, 3-dimensionalreference and positioning systems are interchangeable and as the velocity of transmission ofinformation, the speed of light, is supposed to be infinite, the Newtonian reference systemsare not retarded but immediate.
      • SEE
  4. Dec 2021
  5. May 2021
    1. LocationManager can provide a GPS location (lat,long) every second. Meanwhile, TelephonyManager gives the cellID=(mmc,mcc,lac,cid) the radio is currently camping on. A cellID database[1], allows to know the (lat,long) of each CellID. What is left is to draw the itinerary (in red) and, for each second, a cellID-color-coded connection to the cell.

      To design such a map, one needs to use these 2 Android components:

      • LocationManager - provides a GPS location (lat,long) every second
      • TelephonyManager - provides a cellID=(mmc,mcc,lac,cid) the radio is currently camping on

      and cellID database to know the (lat,long) of each cell ID.

  6. Feb 2021
  7. Aug 2020
    1. in June, 2017, a French oil tanker, the Atria, sailed across the Mediterranean, through the Bosporus strait, and into the Black Sea. As the ship approached the Russian city of Novorossiysk, the captain, Gurvan Le Meur, noticed that the ship’s navigation system appeared to have lost its G.P.S. signal. The signal soon returned, but the position it gave was way off. The Atria was apparently some forty kilometres inland, shipwrecked at the airport in Gelendzhik, a Russian resort town.

      This could easily be used to spoof tanker vessels and hijack them electronically.

  8. Jun 2020
  9. May 2020
  10. Apr 2020
  11. Jun 2019
  12. Sep 2018
  13. Jan 2016
  14. Nov 2015
    1. If the space doctor’s ideas were wrong, your phone wouldn’t be able to tell where it was.

      If all of the space boats travel at the same velocity and the same distance from the Earth's surface, the time shift of the on-board clock due to relativity would be the same. The difference between the clocks would be almost the same. How would the trouble appear?