Yo Hal! On Sun, 08 Jan 2017 20:41:25 -0800 Hal Murray <[email protected]> wrote:
> [email protected] said: > >> The Adafruit receiver outputs NMEA format data. The lat/lon values > >> are sent as dddmm.mm format (ddd=degrees, mm.mm=minutes) This > >> restricts the resolution of the values. > > > Yes, easy to see the quantization in the Adafruit plot. > > Something doesn't look quite right. If the problem was as simple as > reduced lat/lon resolution, I'd expect the output to be on a grid. > Instead, what I see is more like a grid that was also missing 1 out > of N slots. Where is that coming from? How do I predict N? Yes, the raw data shows that it is not using all the possible precision. It does skip lat/lons that are representable. I'm almost at 45N, so that partlly explains why the lat missing codes are smaller than the lon missing codes. > I expect it's something like roundoff after the conversion from mm.mm > to meters, or something like that. No rounding happening in gpsd. That is in the raw NMEA. > Just to make sure we are on the same wavelength, this is the graph > I'm looking at. > > https://www.febo.com/pipermail/time-nuts/attachments/20170108/051ba89d/attachm > ent-0003.png Yup. RGDS GARY --------------------------------------------------------------------------- Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 [email protected] Tel:+1 541 382 8588 Veritas liberabit vos. -- Quid est veritas? "If you can’t measure it, you can’t improve it." - Lord Kelvin
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