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From Fellrnr.com, Running tips
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There are some suggestions online that syncing the Spartan before you run will improve GPS accuracy. The idea is that the sync will update the cache of satellite information (SGEE), which in turn will improve accuracy. This satellite information is a prediction of the GPS Ephemeris data, which gives information needed to use a satellite's signal for calculating the watch's position. Because it takes about 30 seconds to get a satellite's Ephemeris, having it preloaded reduces the time to get a usable location (Time To First Fix, TTFF.) This predicted Ephemeris data is not typically used to improve accuracy, but [http://www.telit.com/fileadmin/user_upload/Telit_Jupiter_SGEE_InstantFix_5_App_Note_r1.pdf a publication from Telit] suggests otherwise for the chipset used in the Spartan. The document is rather ambiguous, but I interpret it to mean that for the time between the watch getting an initial fix using the SGEE data and getting the true Ephemeris from the satellite the accuracy will be compromised. Given this should only be for a minute or so at the start of a run, this shouldn't have a practical impact. It's possible the situation may reoccur mid-run as satellites drop below the horizon and others rise up, as the watch will use SGEE data until the new satellites Ephemeris has been downloaded. To test how this worked in practice I did a few runs with the SGEE data expired (>7 days since the last sync) and I found that the GPS accuracy was not impaired. If anything the accuracy might have been better, but I didn't collect enough data for statistical analysis.
=Comparison Table=
{{:Best Running Watch-table}}
