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GPS – New Satellite SOG Errors?

There has been some discussion recently about the new satellite PRN32 or at least an old satellite that has been recommissioned and brought into the GPS system.

It appears that some people are claiming that their GPS receivers software has been coded to count the number of satellites it can detect as 31 whereas there are now 32 satellites – I think this is a misunderstanding …I may be wrong!

It is common practice for programmers to count from 0 to 31 (ie.32) or from 1 to 32 (ie 32) when setting registers or creating arrays to handle data. I am pretty sure that however old your GPS is it can “see” 32 satellites.

There may be an unrelated error on some units eg. the Northstar 941X which started reporting SOG readings of 800 knots – not good! If you are getting strange SOG or COG readings check your supplier for a firmware upgrade – Northstar are offering a fix for their units at http://www.northstarnav.com/en/Downloads/Software-Updates/


Identifying stars while navigating at night...

MySkyLearning to navigate by the stars is like crossing the Rubicon for many sailors so it MySky2is encouraging to see useful devices that could help build confidence when sailing by the stars…

The MySky looks like a toy, but I think it should be taken seriously as a very useful aid…



Features :

  • Identify planets and stars in the night’s sky.
  • Visual and audio guided tours of the stars in your location.
  • Find and display mode for constellations.
  • LCD screen with full colour display.
  • Real time sky maps found.
  • Satellite finder.
  • Ergonomically designed to be comfortable to use and hold.
  • Can be connected to computerised telescopes in order to direct the telescope to the chosen constellation.
  • Adds a GPS function to a non computerised telescope.
  • Includes an SD card.
  • Six hours of battery life.
  • Requires 4 x AA Batteries (not included).
  • Size: 27 x 24 x 9cm.


Celestial navigation

I found this Celestial navigation tutorial by Henning Umland very useful…


Amateur astronomers



Almost 300 personal web pages of amateur and professional astronomers here


Astral nav another tutorial

This interactive site allows you to obtain all the astronomical information necessary to plot navigational lines of position from observations of the altitudes of celestial bodies. A table of data is provided giving both almanac data and altitude corrections for each celestial body that is above the horizon at the place and time that you specify all care of the US Navy ..