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How is a Garmin foot pod calibrated with the 620?

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  • How is a Garmin foot pod calibrated with the 620?

    I have a new Garmin Foot Pod and want to calibrate it so I can use the 620 on my treadmill on bad weather days. I have no idea how to calculate a calibration factor to enter
    into my 620 to allow the foot pod to function accurately.

    Please help as I'm not knowledgeable as to how to calibrate a foot pod properly to work indoors with my 620. My GPS signal outdoors here is quite good, so should I use a remeasured track or simply use GPS to run a specific distance? Then what do I do? DO Iwear the foot pod while I'm running a specific distance to get a calibration number? Please help.

    Thanks!

  • #2
    When using footpod, the GPS is better be off. At he moment (SW 2.30) foot pod overrides GPS but perhaps not in future SW updates.

    To calculate factor based on calibration run.

    Code:
                                    Real Distance
    New factor = Current factor ยท -----------------
                                  Measured distance
    These improve accuracy
    - if you run on treadmill do also the calibration on treadmill (but you should first know the treadmill error)
    - use same shoes in calibration and training
    - footpod should be located same way in the shoe
    - you can also check your calibration in several speeds
    - and repeating same speed is also possible

    And more...
    http://www.dcrainmaker.com/2011/06/g...tion-tool.html

    **********EDIT***CALCULATOR***ADDED**************
    Simple factor calculator.

    Click "CLICK TO EDIT" to change values.

    Change the three input values as needed. The New factor is calculated.

    Just refresh the page (press F5) if something went wrong and start over.

    http://landorrun.blogspot.fi/p/footp...alculator.html

    Location of factor setting:
    Settings - Sensors - Foot Pod - Calibration Factor - Select the calibration value and accept the change
    Last edited by LANDORRUN; 01-11-2014, 04:46 PM. Reason: Location of factor setting

    Comment


    • #3
      Thanks for the info.

      The only problem with using the treadmill to do the calibration is that as Ray Maker says, treadmills are dismally inaccurate.

      So I'll probably use GPS for a relatively straight run and stop and record the distance derived from the 620 GPS and then run the same
      route again with the foot pod on and read that distance (with GPS turned off outside).

      Then I'll use the formula you provided me to calibrate the Garmin foot pod to the 620 via modification of the calibration factor on the 620.

      Is that correct?

      Comment


      • #4
        > you can also check your calibration in several speeds

        Yes I found my calibration factor changed a fair bit with speed. Rather reminded me why I bought a GPS watch in the first place!

        Comment


        • #5
          Tim,

          Is my (above ) plan a good method?

          Or should I find a route of known pre-measured distance and use that to calibrate?

          Comment


          • #6
            I only really use the foot pod for pace on a treadmill so did my calibrations there. At moment I am only using one treadmill model as the treadmills in the the gym I goto are all the same model. OK it might change a bit machine to machine but haven't noticed.

            So in answer to your question suggest do the calibration it in the environment where you want to use it and also at the pace you normally run.

            Comment


            • #7
              Thanks. If pace is accurate with the foot pod on a treadmill, distance and speed should be too. Correct?

              Only problem is you have no way of knowing if the treadmill you're using for data readout and calibration such as pace is anywhere near accurate. Per DC Rainmaker anyways.

              Comment


              • #8
                Originally posted by TIMGROSE View Post
                I only really use the foot pod for pace on a treadmill so did my calibrations there. At moment I am only using one treadmill model as the treadmills in the the gym I goto are all the same model. OK it might change a bit machine to machine but haven't noticed.

                So in answer to your question suggest do the calibration it in the environment where you want to use it and also at the pace you normally run.
                Agree: After doing my calibration on a track several times, I also came to the conclusion that I was better off doing the calibration on the treadmill. Probably due to a slightly different running gait on the treadmill, the calibration set outdoors was never reflected on the various treadmills I use. I appreciate treadmills own calibration can be out a few % as can gps. But over time this proved better than setting it on an outdoor track given that I only use the Footpod for treadmill work.

                I usually run one treadmill mile at somewhere between my 5k and 10k pace, taking the forerunner distance at the treadmill mile. Then use the formula above. This gives me a decent calibration for my intervals and threshold workouts. There are about 20 treadmills at my gym, all slightly different compared to the footpod. The footpod gives me consistency in pacing across all treadmills

                Comment


                • #9
                  Originally posted by MONTYZUMO View Post
                  Agree: After doing my calibration on a track several times, I also came to the conclusion that I was better off doing the calibration on the treadmill. Probably due to a slightly different running gait on the treadmill, the calibration set outdoors was never reflected on the various treadmills I use. I appreciate treadmills own calibration can be out a few % as can gps. But over time this proved better than setting it on an outdoor track given that I only use the Footpod for treadmill work.

                  I usually run one treadmill mile at somewhere between my 5k and 10k pace, taking the forerunner distance at the treadmill mile. Then use the formula above. This gives me a decent calibration for my intervals and threshold workouts. There are about 20 treadmills at my gym, all slightly different compared to the footpod. The footpod gives me consistency in pacing across all treadmills
                  I follow you and it makes a lot of sense.

                  The only issue is you are probably not getting true distance readings on the treadmill to use for your calibration. Perhaps that does not matter since your gait is different on treadmill vs. outside as you said, and by calibrating the forerunner to the treadmill you at least have consistency across the various treadmills
                  you may use from time to time.

                  For really accurate calibration however, a known accurate distance should be used. But that probably does not matter due to the above variability.

                  Comment


                  • #10
                    I guess there is a certain reassurance in seeing what the treadmill says for pace & distance being reflected on your Forerunner. So yes get pace right and distance/speed will be too - well assuming the units are the same of course.

                    It's clearly "easier" on a treadmill (well at 0%) but when it is cold/dark/wet/snowing outside then certainly beats doing nothing.

                    Comment


                    • #11
                      Tim, it's certainly true, as here in the northeast USA, it is indeed cold, dark, wet, snowy AND slippery outside to be doing math calibrations and GPS runs solely for the purpose of calibration.

                      Comment


                      • #12
                        For outdoor running I have measured my calibration route at
                        http://www.milermeter.com/
                        Then I run it with various speeds.

                        I don't run much indoors. I don't have good understanding how outdoor calibration works on treadmill. I assume that the Dynastream algorithm is designed for normal outdoor running. Treadmill running is a bit different for the acceleration sensor.

                        Comment


                        • #13
                          Thanks for the link to that site. It's helpful!

                          I wish Garmin had more written information on calibration of the foot pod to the 620 on a treadmill OR outside. I suppose outside is easy, but time consuming.

                          Maybe the foot pod is actually 95 percent accurate when used on the treadmill as it's supposed to be outdoors without calibration. I just don't have any confidence that my treadmill telemetry is accurate. So I'll never know.

                          Comment


                          • #14
                            It seems that there is some real Dynastream knowledge in this forum. So I copy some messages here.

                            Originally posted by T_SMIT View Post
                            Running on a treadmill is just different. From a dynamic point of view, your feet and legs should do the same thing, but the forced pace is not the same as what you'd do out on a track or trail. And most treadmills are not especially accurate - if the speed indication is within 5% of truth you're doing really well. If you try to calibrate the treadmill (by measuring the belt length and then counting revolutions) you should be running on it while you do the calibration...
                            Originally posted by T_SMIT View Post
                            The best way to calibrate the footpod is to go to a local track, or a trail that has distance markers that you know are accurate. Warm up for about 1 km or so, and then put the watch into calibrate mode and run the test distance. If your track is 400 meters then you can do a couple of laps for more accuracy.

                            The footpod accuracy spec of 95% is statistical, because the distance it determines is somewhat dependent on characteristics of your gait that it can't measure. Some people end up with a calibration offset of 10% or even more, but once that's done they can use the footpod repeatably and accurately, as long as their gait doesn't change appreciably. Note that 'gait' and 'stride length' are not the same thing. When you calibrate at a given speed, on a given running surface, you can expect the footpod to give repeatable results within a reasonable speed range around the speed you calibrated at, on the same surface. If you calibrate on pavement and then go run on gravel or on an offroad trail, you can expect some minor errors.

                            You can also calibrate the footpod to your treadmill, but you might then find that your real-world distance measurement is off.
                            Originally posted by T_SMIT View Post
                            The inertial technology and the way that the footpod measures the speed is completely compatible with treadmills.

                            The footpod calibration correction depends primarily on your running gait. It is quite natural to run slightly differently on a treadmill than you do on a non-moving surface, and therefore it is probable that your footpod calibration would need to be a bit different to match the treadmill speed or distance indication. How different is your calibration? I typically notice that our treadmill is about 5% pessimistic compared to the footpod.

                            If your footpod is accurate when you run outdoors then I'd be inclined to leave the calibration alone, since it is outside that you don't have other speed indication.
                            Originally posted by T_SMIT View Post
                            While the footpod data will be most accurate when you run under conditions that are most similar to the conditions when the footpod was calibrated, the divergence from 'truth' should not be too abrupt for varying pace and terrain conditions. I've run 30 km trail races including over 1200 meters vertical where the footpod and GPS gave results within 100m of each other at the end; and my pace was definitely all over the map during those runs. In any event the footpod data should be self consistent such that you can use it for relative pacing during a run.

                            It is important that your pod be snugly mounted on the shoe with the long axis of the pod in the fore-aft direction. If your pod shifts during your run, then all bets are off... Another thing is that the dynamics (acceleration) are a lot higher nearer the toe; so if you have a choice and you can mount the pod closer to the top of the laces, this can help to make your data more consistent.
                            Last edited by LANDORRUN; 12-25-2013, 12:27 PM.

                            Comment


                            • #15
                              @Landorrun Thanks for all that information. So if I'm only going to use the foot pod on the treadmill indoors and use GPS outdoors, I should calibrate on the treadmill, after warming up, and at the pace I usually run on the treadmill. So there will be inaccuracies from the "real world"
                              outside running due to the inherent incorrect calibration of the treadmill. Actually we will have no idea IF the treadmill is accurate or not and if not, by how much it is mis calibrated. Well, at least the numbers should be consistent throughout the winter even if they are wrong!

                              One problem. The 620 does not have the 610's calibration software. It merely lets one enter a calibration number...

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