Re: Determining distance via GPS readings
The max distance error for GPS ranging that I have done is about 10 yards.
I don't use the GPS displayed distance, I recalculate the distance in a spreadsheet or on a calculator.
I like the idea of using the known values and extrapolating the interval distance come-up. This should also be able to work for known data fired at different temp and elevations. Select the current temp or elevation and the computer uses known data from two or several sets of known data and provides the new come-up.
The is a chart called "Data Summary" that does this via paper.