Next Generation Forerunner Tested

Preliminary Test of Next Generation Garmin Forerunner As reported last month, Garmin has already begun rolling out a new generation of gadgets for runners.  The “10” series uses a new GPS chipset (SiRFstarIV) and updated software with features (trademarked “HotFix”) to more quickly acquire satellite and improve performance on wooded trails under dense trees and in the downtown canyons of large cities. A colleague with a Forerunner 305 and a new Forerunner 310XT is helping me to confirm whether the performance of the “10” series is significantly better than the Forerunner 305.  He recently tested both devices on two laps around a 5k loop at Green Lakes State Park at Fayetteville, NY.  As can be seen in the topographic map at the right, the test loop is reasonably challenging for GPS with long sections of forest canopy and steep hillsides above the lakeshore trail. Satellite Acquistion.  My colleague reported that cold start satellite acquisition takes noticeably less time with the new 310XT.  Below are sample data from two cold start tests.  As you can see, the new device is consistently quicker.  The large day-to-day variation in the time for satellite acquisition should be no surprise to current users of Garmin Forerunners. Forerunner 305 310XT Test 1 1:34 1:12 Test 2 0:59 0:24 Distance Accuracy.  The tracks from both devices measured 6.21 miles.  Any differences due to errors in the tracks seemed to average out so there was no meaningful difference in this test. Track Accuracy.  One easy way to evaluate the accuracy of a GPS track is to record multiple laps of a short but challenging loop.  For this analysis, I uploaded the gpx files from each device into Google Earth.  The tracks for both devices were generally consistent.  However, there were a few locations around the loop that showed noticeable differences in the performance of the two devices.  The images below show details of the tracks over the trail connecting the two lakes.  Forerunner 305 Forerunner 310XT Note the spread of the four tracks over the connector trail. All of the 310XT tracks are correctly grouped on the south side of the stream. Note that one of the 305 tracks strays  into the lake. The 310XT tracks more consistently follow the actual trail. Preliminary Conclusion.  More testing needs to be done but this preliminary test suggests that there is a noticeable improvement in performance under difficult conditions with the “10” series of Garmin GPS devices.  If your running is on trails in dense forests and in deep canyons, the "10" series will probably seem to be worth the higher price.