<div style="FONT-FAMILY: Times New Roman; COLOR: rgb(0,0,0); FONT-SIZE: 16px"><DIV>&nbsp;You can learn something new every day!</DIV><DIV>&nbsp;</DIV><DIV><SPAN class=misspelled>Dave</SPAN> B.</DIV><DIV>&nbsp;</DIV><DIV>&nbsp;</DIV><SPAN style="FONT-SIZE: 12px; FONT-FAMILY: arial; COLOR: #000000">On 05/07/13, <SPAN><SPAN class=misspelled>Mike</SPAN> S&lt;<SPAN class=misspelled>mikes</SPAN>@FLATSURFACE.COM&gt;</SPAN> wrote:</SPAN><DIV>&nbsp;</DIV><DIV style="FONT-SIZE: 12px; FONT-FAMILY: arial; COLOR: #000000">On 5/7/2013 11:01 AM, <SPAN class=misspelled>David</SPAN> <SPAN class=misspelled>Bjorkman</SPAN> wrote:<BR>&gt; Before you go blaming the <SPAN class=misspelled>speedo</SPAN> (which is well documented as being<BR>&gt; off) and take the GPS as the final word. do not forget that there is an<BR>&gt; error in accuracy in your GPS also. There should be a place you can<BR>&gt; check which satellites are being used by your GPS and the expected<BR>&gt; accuracy. One may be surprised to find that that error can be more than<BR>&gt; just a few feet.<BR><BR>Modern GPS units don't compute speed based on how long it takes to move<BR>between points, so are not subject to errors in location.<BR><BR>They measure the <SPAN class=misspelled>Doppler</SPAN> shifts of the carriers.<BR><BR>"Generally most manufacturers claim a 0.1MPH tolerance with speed<BR>readings, however will go as far to say a 0.5MPH inaccuracy is possible,<BR>to make allowances for any satellite signal variations beyond their<BR>control." - <A class=parsedLink href="http://gpssystems.net/accurate-gpsbased-speedometer/" target=_blank><SPAN class=misspelled>http</SPAN>://<SPAN class=misspelled>gpssystems</SPAN>.net/accurate-<SPAN class=misspelled>gpsbased</SPAN>-<SPAN class=misspelled>speedometer</SPAN>/</A><BR></DIV></div>