XPost: misc.phone.mobile.iphone   
   From: ithinkiam@gmail.com   
      
   Alan Browne  wrote:   
   > On 2025-12-17 02:45, Chris wrote:   
   >   
   >> If you understood the code you'd know that the WPS DB returns the lat/lon   
   >> as a 64bit integer and the python script converts into a float with a   
   >> simple multiplication  of 1e-8. Anything beyond the 8th dp is noise.   
   >   
   > Where a GPS position in Lat/Long (base 10 real*) is concerned, anything   
   > beyond the 5th dp is noise in almost all cases including SBAS aided.**   
   >   
   > Even beyond the the 4th dp, it is likely noise in most cases.   
      
   I accept that.   
      
   I was trying to explain to Donald that what he believes to be factual   
   isn't. Simply by reading the scripts and not even needing to understanding   
   what the variables mean.   
      
   > If Lat is represented as a fraction of a semi-circle, then a signed 32   
   > bit integer is more than adequate for general purposes.   
      
   TBH I was surprised to see it represented as a 64bit int. I believe python   
   stores floats as doubles, hence the meaningless precision in the output.   
      
   > Likewise Longitude as a fraction of a circle.   
   > (LSB=0.0046...m and 0.0093...m respectively - though you could represent   
   > Lat as a circle as well at the loss of 1 bit of resolution).   
   >   
   > *by real I mean number line real, not computer language "real" type.   
   >   
   > **(Excluding survey RTK measurements - which are baseline lengths, not   
   > L/L but might be tied to a precise L/L - there 1cm+1mm/km error is common)   
   >   
      
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