Spiky extra lines (Forerunner 645)

Discussion in 'Garmin GPS' started by HattrickG, Feb 26, 2021.

  1. HattrickG

    HattrickG

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    I have been using basic Forerunner 645 for some time. On yesterday's walk, for the first time ever, the plot of my walk had a series of extra lines spiking back and forward. I checked by looking at the individual kms. All the spiky lines, which looked like several extra kms were in fact all in one km in the middle of my walk, at a point which I have visited many times in the past.. Presumably this was due to a loss of signal. I was not aware of any unusual action on my part, nor any warning from the watch, Does anyone have an answer as to what may have caused it. Also advice on how to avoid it in future. Also advice about removing the extra lines from the plotted trace (not essential, as no distance seems to have been added).
     
    HattrickG, Feb 26, 2021
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  2. HattrickG

    Nuvi-Nebie Moderator

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    I'm a bit confused about the spikes "Not adding any distance" to the walk when you also say "several extra kms" were inserted into a1km section of the walk, I can't see how extra track distance can be added without the total distance being increased.

    This type of problem can occur if you take a long rest in the middle of the walk / run, let us say you was walking across a field where the total distance is 1km, if you stop for a 2 hour picnic in the middle of the field before continuing the walk, it is quite common to find that the Track recorded on the GPS is say 1.5km, you would also see extra Track lines displayed at the picnic site even if you didn't move, this is due to GPS positioning errors where your location is calculated incorrectly, each error adds a 'move' to your current stationary position and all the false moves add to the total distance measured

    If you didn't remain stationary at the place where the extra lines were show, the only explanation I can think of is that at this point in the walk the GPS repeatedly miss calculated it's position (due to a very poor satellite reception) which resulted in these 'false moves' being added to the Track
     
    Nuvi-Nebie, Feb 26, 2021
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  3. HattrickG

    HattrickG

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    Thanks Nuvi-Nebie. No pause involved this time though.
    I went up a road, turned and went back down. Reasonably open area, suburban housing estate, with houses set back from road and no large trees or other obstructions to interrupt line-of-site satellite cover.
    Regarding the distance: What I meant was that the length of the traces on the plot would have amounted to several km. The fact that all these lines were within one highlighted km suggests that the plot did not result in any appreciable distance being added to the total.
     
    Last edited: Feb 26, 2021
    HattrickG, Feb 26, 2021
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