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Garmin pace got wonky today...what is wrong? (Read 121 times)

kristin10185


Skirt Runner

    On this morning's run, my Garmin started being wonky.   Every second the pace would change drastically. ie I would look at it for 10 seconds and would see it go from 3:03, one second later 18:36, then 7:50, 13:35, 4:10....ect. Pretty sure the distance was slightly innacurate too. I ran a route I have run many, many times and it seemed to be measured about .3 miles short. Any ideas? Is sonething wrong with it, did Ido sonething by accident (I didn't change anything but I was screwing around with the data fields after my last run), or could it have been due to rain and cloud coverage?

    PRs:   5K- 28:16 (5/5/13)      10K- 1:00:13 (10/27/13)    4M- 41:43 (9/7/13)   15K- 1:34:25  (8/17/13)    10M- 1:56:30 (4/6/14)     HM- 2:20:16 (4/13/14)     Full- 5:55:33 (11/1/15)

     

    I started a blog about running :) Check it out if you care to

    kristin10185


    Skirt Runner

      *something not sonething...phone won't let me edit

      PRs:   5K- 28:16 (5/5/13)      10K- 1:00:13 (10/27/13)    4M- 41:43 (9/7/13)   15K- 1:34:25  (8/17/13)    10M- 1:56:30 (4/6/14)     HM- 2:20:16 (4/13/14)     Full- 5:55:33 (11/1/15)

       

      I started a blog about running :) Check it out if you care to

      joescott


        What model are you using?  Do you know how long you had a GPS fix before you started running?  Rain and cloud coverage should have had nothing to do with it, but what kind of route was it?  Were you in heavy tree cover, for example?

        - Joe

        We are fragile creatures on collision with our judgment day.

          sounds like you somehow changed the pace from "average speed" to "instantaneous speed"

          ---------

          joescott


            sounds like you somehow changed the pace from "average speed" to "instantaneous speed"

             

            No, even if she changed it to current pace it should not vary from 3:03 to 18:36.  Current pace is definitely more jittery than average pace, but not that much!  I suspect there were GPS reception issues, for whatever reason.

            - Joe

            We are fragile creatures on collision with our judgment day.

            joescott


              But now that I'm thinking about it, depending on the device, if it somehow got set to biking mode, then the current pace filter would be turned off and you could indeed have a situation where it was reporting "instantaneous" pace and jumping wildly, which would be made even worse in a poor GPS reception situation.

              - Joe

              We are fragile creatures on collision with our judgment day.

              kristin10185


              Skirt Runner

                What model are you using?  Do you know how long you had a GPS fix before you started running?  Rain and cloud coverage should have had nothing to do with it, but what kind of route was it?  Were you in heavy tree cover, for example?

                 

                I have the ForeRunner 10. The route is the same one I use for all my runs during the week, I just have different variations of it depending on how many miles I need. Starts on city streets- minimal trees, lots of buildings but none too tall as it is a residential area (nothing over 4 stories), then I go into a park (more trees) then out to a jogging path down by the water (no trees or buildings), and back to my apartment on the city streets. My Garmin always takes a long time to "Get Location" before my run starts (usually 2-3 minutes) but I did notice today it took longer than usual (maybe 5 minutes).

                PRs:   5K- 28:16 (5/5/13)      10K- 1:00:13 (10/27/13)    4M- 41:43 (9/7/13)   15K- 1:34:25  (8/17/13)    10M- 1:56:30 (4/6/14)     HM- 2:20:16 (4/13/14)     Full- 5:55:33 (11/1/15)

                 

                I started a blog about running :) Check it out if you care to


                Mmmmm...beer

                  My FR10 did this on one of my long runs.  I was running a 1.5 mile loop and on one corner I noticed several times that the pace would swing from around 6 flat to mid 9's (I was running around 8 flat).  It only happened on that one corner, so I'm guessing there was some sort of interference with the gps signal there.

                  -Dave

                  My running blog

                  Goals | sub-18 5k | sub-3 marathon 2:56:46!!

                  AmoresPerros


                  Options,Account, Forums

                    I thought I read or heard that some watches averaged several data points to compute "instantaneous pace" ? If so, if you can adjust how many points are used in this smoothing, that seems like it would let you adjust (a bit) how much you're trading off "instant feedback" for smoothness.

                    It's a 5k. It hurt like hell...then I tried to pick it up. The end.


                    an amazing likeness

                      That can happen when it gets an erroneous data point along your track.  All the sudden the distance between point 1...2...3 isn't linear and the computed pace has to jump around in response.

                       

                      You ran:   1 ----- 2 -----3 ------ 4

                       

                      Due to signaling errors, the gps track points are out of whack, like:

                       

                      1 ----- 2         4 ----5  ---- 6

                      |          |

                      3 ------

                       

                      The pace has to jump around.

                       

                      I'll bet the track on your GPS map here on RA is way off what you actually ran.

                      Acceptable at a dance, invaluable in a shipwreck.

                        The same thing happened to me once with a Garmin 205.  It was a long time ago and hasn't happen again so I wouldn't worry about it.

                         

                        I can't find the entry in my log but I believe I actually used "Wonky" in my notes to describe the event.


                        Mmmmm...beer

                           

                          I'll bet the track on your GPS map here on RA is way off what you actually ran.

                           

                          Never thought to look at the map of my run.  You're right, there's a couple of loops where my path on that corner cuts across the water (the trail goes around a lake), so it missed some data points going around that corner and the path just picked up when it caught the next point.

                          -Dave

                          My running blog

                          Goals | sub-18 5k | sub-3 marathon 2:56:46!!

                          joescott


                             I have the ForeRunner 10. The route is the same one I use for all my runs during the week, I just have different variations of it depending on how many miles I need. Starts on city streets- minimal trees, lots of buildings but none too tall as it is a residential area (nothing over 4 stories), then I go into a park (more trees) then out to a jogging path down by the water (no trees or buildings), and back to my apartment on the city streets. My Garmin always takes a long time to "Get Location" before my run starts (usually 2-3 minutes) but I did notice today it took longer than usual (maybe 5 minutes).

                             

                            OK, this is helpful information.  If it took 5 minutes to get a fix that's a good indicator that it was struggling to get a good fix right out of the gate.  If you took off immediately after getting a fix this would have made the problem worse.  (Not blaming the customer, just explaining the situation -- it's a reasonable expectation that you should be able to take off the moment your timer screen pops up on the 10).  I suspect you had a low-quality GPS fix from the start and after you started running the watch continued to struggle to get a good fix.  Without a good fix you will get worse positional errors which will translate directly into pace going bezerko.  One practical thing you can do in the future is after you have a GPS fix just wait another minute or two in a static location and give that sucker just a little more time to get a few more satellites and a better fix.

                             

                            @AmoresPerros:  Yes, the Garmin running watches effectively average the data over many points (low pass filter) to create the "current pace."  On the Forerunner 10 this is actually a fairly sophisticated adaptive filter.  I don't like using the term "instantaneous pace" because in my mind that technically implies no filtering whatsoever, just delta time/delta distance on a point by point basis, or worse yet, raw GPS speed (reciprocal thereof).  Garmins don't do this (except in weird cases, like I think the 910 will do this if you run with it in biking mode).  True "instantaneous" pace will indeed jump all over like crazy.

                            - Joe

                            We are fragile creatures on collision with our judgment day.

                            kristin10185


                            Skirt Runner

                              After getting home from work I got to upload my run onto Garminconnect. The map of the run is wonky too, it looked like I was zigzagging all around the road like I was drunk. Is this consistent with what people were thinking was the problem? (not me being drunk Wink which I wasn't, the zig-zaggy map)

                              PRs:   5K- 28:16 (5/5/13)      10K- 1:00:13 (10/27/13)    4M- 41:43 (9/7/13)   15K- 1:34:25  (8/17/13)    10M- 1:56:30 (4/6/14)     HM- 2:20:16 (4/13/14)     Full- 5:55:33 (11/1/15)

                               

                              I started a blog about running :) Check it out if you care to


                              Best Present Ever

                                This has happened to me.  I find it ridiculously amusing.  When I download the map, it shows me doing things like darting through the woods straight across rivers and ravines, then disapparating and appearing down the road a piece.    It  happens rarely and without any particular pattern that I've noticed.

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