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


1 thought on “GPS – New Satellite SOG Errors?

  1. It appears that the GPS receievrs which did count from 0 to 31 may have casued a problem because there never was a PRN0 so the units can in fact only track 31 satellites instead of the 32 which are at “healthy” at the moment.

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