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Garmin 45 / Short Mile Measurement (Read 69 times)

dcowboys31


    Hello,

     

    I have run the same exact 4 mile route, the past four years, out two miles back two miles, straight  road and know the exact mile marks and yesterday for the second time this month it measured the distance way off on the first part. I had surgery on my leg at the end of May and started walking the route and a few weeks ago the first mile measured .84. Thought is was due perhaps to me walking.

     

    Last night I ran and it was off again (short on the first 2 miles) and this time when I downloaded the run the map shows the first 2 miles going down a route I did not take, it was inside the normal road I run. If you look at the workout on my log from last night I usually run a straight route down rt 135 and back and for some reason last night it looks as if I was running a shorter distance going out, like a shortcut off road.

     

    I imagine it is some sort of GPS signal and have only been using this new watch since January, but it never happened before on my old watch (Garmin 25)  just curious if anyone has any feedback on what could cause this.

     

    Thank You,

     

    Jay

    CanadianMeg


    Half Faster Runners 2023

      I suspect Garmin was having issues yesterday. My map for yesterday's run shows me running half a mile north of the road I ran down and across a lake. I think technology isn't perfect and sometimes it gives a bad record. I wouldn't stress it unless you are seeing the same issue every day and then I would contact Garmin directly.

      Half Fanatic #9292. 

      Game Admin for RA Running Game 2023.


      an amazing likeness

        Sounds like, and in looking at your workout's map, it looks like a case of 'GPS drift' during the workout. The physical track you took and the GPS track diverged, so the distance calculations are off.

         

        It happens every now and then. The Garmin selects which GPS satellites it will use for the session, and then along the route it looses signal quality for some environmental reason and the satellite constellation in use is no longer good.

        Acceptable at a dance, invaluable in a shipwreck.

        dcowboys31


          Thank you for the reply, for me it is not a big deal at all, but after four years of running it never once happened as I always have run the same exact routes so the mileage markers (even if there off a bit) have been very consistent.

           

          Jay

          kcam


            Since the track was off only on the first two miles but cleanly tracked you  the 2miles back I'd guess that, for whatever reason, your watch hadn't fully locked onto enough satellites before you started to run.

            bobinpittsburgh


            Lord of the Manor

              I suspect Garmin was having issues yesterday. My map for yesterday's run shows me running half a mile north of the road I ran down and across a lake. I think technology isn't perfect and sometimes it gives a bad record. I wouldn't stress it unless you are seeing the same issue every day and then I would contact Garmin directly.

               

              Mine had similar issues yesterday.

              The amusement never ends

              sub520


                Mine had similar issues the past 3 days actually.  It started once I applied the latest update, so I thought it was a software bug.  But it is exactly what all of you are describing.  For me, I start my watch, and about 20 seconds into my run, I have covered .12 to .15 miles.  Then my first mile is extremely fast and the rest of the workout is fine.  When I look at the map online, the overall shape/path of my run is accurate, it just that right after I start my watch, there is a long straight line and the whole run is shifted that distance over.  So i have the same thing where i can see the roads I ran on, but the entire shape of the run is shifted by the distance of that long straight line right after I start my watch.

                  I have had similar problems.  I once had a Garmin Forerunner 201 that measured a half marathon, on a certified course, at only 12.46 miles.  The previous year, it correctly measured that same half marathon on the exact same course.

                   

                  Then I got a Forerunner 310xt.  It had the capability of recording a waypoint and displaying the distance to that waypoint, so I recorded a waypoint in front of my house.  On startup, I would wait until the display said that it was locked in, then check the distance to the waypoint under my feet.  That distance, which should have been near zero, was sometimes more than 0.1 mile.  If I waited long enough, that distance would eventually reduce to near zero.

                   

                  My current Garmin Forerunner 235 does the same thing.  I just check the displayed distance against landmarks at known distances.  It it is accurate at 0.5 to 1.0 miles, it was properly locked in at the start.

                   

                  My conclusion is that the software that calculates the accuracy is not as good as Garmin thinks it is.  Especially at startup.  A workaround is to start the watch 15 minutes before starting out to give it plenty of time to properly lock in.

                  Altair5


                    My Garmin also sometimes has glitches, like showing I ran a quarter mile in a different direction in a few seconds! Sometimes I could guess the cause: nearby lightning, standing next to a running car and going inside a concrete bunker to use the bathroom, all of which may have interfered with the signal. More frequent is the watch may show an impossible fast pace spike for the first few seconds of my run. I get different calculations of the distance depending on what I use: official race distance, Map My Run, Garmin or Strava (both of those use the same data, so why the difference?). The difference is usually less than .2 miles (1/5 of a mile) so not a big deal for training runs. Of more concern is when I want to run at a certain fast pace for a short time or distance. It seems to take a few seconds for the display to show the current pace, so often I will have continued to accelerate past my goal speed while waiting. Biggest problem is wonky heart rate readings. This is usually due to a loose strap, so I try to remember to keep it tight. I also think it may happen when the wrist gets wet from rain or sweat. Still the Garmin is an improvement on measuring distance by a car's odometer or drawing lines of map segments on a piece of paper and estimating with the map scale!

                    "My dear, here we must run as fast as we can, just to stay in place. And if you wish to go anywhere you must run twice as fast as that.” 

                    bobinpittsburgh


                    Lord of the Manor

                      Ot the opposite end of the spectrum, my Forerunner 45 told me I was running at a 2:37 per mile pace this morning.

                      The amusement never ends

                      runmichigan


                        My Garmin 945 did something similar last night (7/3).  It told me I ran a 3:54 mile when I was running about 9:30 miles.  When I viewed the track for my out and back run, it showed quite a different track for the return.

                         

                        Update:  I ran a different figure 8 loop twice on 7/4 and this time there were no issues.

                        LedLincoln


                        not bad for mile 25

                          My Garmin has been fine, but DD complained of considerable nuttiness in the first part of her run.

                          runmichigan


                            For anyone that encountered issues with there Garmin GPS tracks of their workouts through 7/5/2022, see this article DCRainmaker Article.


                            an amazing likeness

                              That's sort of odd in that the first time the Sony EPO file problem hit, the GPS tracks were mostly correct in distance and layout, but shifted (primarily west to my recall?).  This time the tracks are just fully whacked and often start out ok, then part way through the workout the GPS lock goes asunder...

                               

                              After having a two workout GPS tracks messed up, as an experiment I changed my device to use glonass & galileo only to see if made a difference...but now that there's a corrected EPO file being deployed...doesn't matter.

                              Acceptable at a dance, invaluable in a shipwreck.

                              Fredford66


                              Running Musician

                                Thanks for sharing the article - it explains some weirdness I've seen, such as this track workout:

                                 

                                 

                                I don't think it explains why my son's Garmin watch consistently records 1.01 miles run for every 1.00 miles that my watch records.  I guess different Garmin models have different ideas of how far a mile is....  Or is the explanation about different chipsets exactly the issue between my watch and his?

                                5k 23:48.45 (3/22); 4M 31:26 (2/22); 5M 38:57 (11/22); 10k 49:24 (10/22); Half 1:48:32 (10/22)

                                Upcoming race(s): Winter Series #5 Trail 10k, 2/4; E. Murray Todd Half, 3/12
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