Hi At the often quoted 1.5 ns / meter error level, that would be almost 3.5 ns. At the “worst case” 3 ns / meter you would almost get to 7 ns.
Bob > On Dec 7, 2016, at 7:17 PM, Mark Sims <[email protected]> wrote: > > It depends upon your lat and lon, but figure about 10 feet. Basically > earth circumference is 24,000 miles * 5280 feet per mile divided by (2**24) > (bits in the sign+significand of a 32 bit float). The math works out to 7.5 > feet, but one always has to pay some imprecise math tax... > > One can see the quantization effect with Heather V5. Heather can calculate > and display a lat/lon scattergram of the receiver fixes as they come in. The > default is a 10x10 grid at 3 meters per division. The lat/lon coordinates > are "plotted" in an internal bit map. The coordinates are also stored as > 32-bit floats in the plot queue. If one tells Heather to change the scale > factor (meters/division) of the scattergram, it is re-created from the > low-res plot queue data. > > gpsd1.gif is from the full-res double precision data the receiver sends, > gpsd2.gif is from the single precision floating point plot queue data. The > center points of two scattergrams are slightly different because it was > changed to the current GPS coordinate when the plot was re-generated. The > pixel colors change every hour. > > -------------------- > >> What does the chop-off translate to in terms of distance? > <gpsd1.gif><gpsd2.gif>_______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
