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    <div class="moz-cite-prefix">On 1/12/20 7:46 am, Andrea Mazzoleni
      wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAGKKSfXCTjKw+oRjUZP0Zw+G7owEFYz1GPfQUzvcF0Z85U9uvA@mail.gmail.com">
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            <div>I recently wrote a series of diary entries about my
              experience with the accuracy of one-device GPS precision.
              I concluded with a comparison of three devices I had
              personal experience with including a new Garmin GPSMAP
              66sr which I posted here: <a
                href="https://www.openstreetmap.org/user/bobwz/diary/394711"
                target="_blank" moz-do-not-send="true">https://www.openstreetmap.org/user/bobwz/diary/394711</a></div>
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        <div>Very interesting!<br>
        </div>
        <div><br>
        </div>
        <div>Here you can find the mapping of my tests with GPSMAP 65s
          and eTrex 30x:<br>
        </div>
        <div><br>
        </div>
        <div><a href="https://ibb.co/bKvpxYG" moz-do-not-send="true">https://ibb.co/bKvpxYG</a></div>
        <div><br>
        </div>
        <div>It's a circular trail repeated 5 times with one point every
          second. <br>
        </div>
        <div><br>
        </div>
        <div>I repeated it again with the recording frequency set to
          Auto, and the GPSMAP lost a bit in accuracy, so better to
          stick to one point every second.</div>
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    <p><br>
    </p>
    <p>Think your confusing two terms;</p>
    <p> resolution¬† <br>
    </p>
    <p><br>
    </p>
    <p>accuracy</p>
    <p><br>
    </p>
    <p>With increased points along a way there is increased resolution.
      <br>
    </p>
    <p>The accuracy does not follow with increased number of points
      unless they are all for the same location so averaging those
      points reduces noise thus increasing accuracy. <br>
    </p>
    <blockquote type="cite"
cite="mid:CAGKKSfXCTjKw+oRjUZP0Zw+G7owEFYz1GPfQUzvcF0Z85U9uvA@mail.gmail.com"><br>
      <div class="gmail_quote">
        <div dir="ltr" class="gmail_attr">On Mon, Nov 30, 2020 at 3:45
          PM Lindsay Barnes <<a href="mailto:newsspeak11@gmail.com"
            moz-do-not-send="true">newsspeak11@gmail.com</a>> wrote:<br>
        </div>
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          0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
          <div dir="ltr">
            <div>I recently wrote a series of diary entries about my
              experience with the accuracy of one-device GPS precision.
              I concluded with a comparison of three devices I had
              personal experience with including a new Garmin GPSMAP
              66sr which I posted here: <a
                href="https://www.openstreetmap.org/user/bobwz/diary/394711"
                target="_blank" moz-do-not-send="true">https://www.openstreetmap.org/user/bobwz/diary/394711</a></div>
            <div><br>
            </div>
            <div>In short, multi-band and multi-GNSS devices do offer in
              an increase in precision and accuracy and we're seeing
              this become more common in a standard smartphone. However,
              that level of precision is not necessary in most cases. It
              is most helpful in areas without good satellite imagery
              coverage or where imagery lacks reference points (like in
              wooded trail areas, as mentioned). This is compounded by
              the fact that one GPS device has a floor to how accurate
              it can be due to the nature of the system and interference
              from the natural landscape, as was mentioned. Furthermore,
              mult-band and mult-GNSS chips are becoming more common in
              smartphones and I would expect this level of precision
              available to most mappers without the need for specialty
              equipment over the next 5-ish years.</div>
            <div><br>
            </div>
            <div>To answer your question about tags, a comment can be
              added in the source field of a changeset, but in my
              opinion most mappers will not dig too deep into a change
              to determine how precise the mapper may have been .
              Satellite imagery is generally used as the source of truth
              and if a mapped feature varies substantially from the
              imagery, mappers are inclined to move the feature to match
              imagery without researching how the feature was initially
              created. The good news is that if satellite imagery in
              unclear or lacks reference marks, mappers will usually
              leave features alone unless they have personal knowledge
              of an area or are working off a tasking manager.<br>
            </div>
          </div>
          <br>
          <div class="gmail_quote">
            <div dir="ltr" class="gmail_attr">On Mon, Nov 30, 2020 at
              8:36 AM Andrea Mazzoleni <<a
                href="mailto:amadvance@gmail.com" target="_blank"
                moz-do-not-send="true">amadvance@gmail.com</a>>
              wrote:<br>
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                <div class="gmail_quote">
                  <div dir="ltr" class="gmail_attr">On Mon, Nov 30, 2020
                    at 12:27 PM Warin <<a
                      href="mailto:61sundowner@gmail.com"
                      target="_blank" moz-do-not-send="true">61sundowner@gmail.com</a>>
                    wrote:<br>
                  </div>
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                    <div>If the intention is to indicate the
                      error/accuracy/uncertainty then tag/state that.
                      The better GPS devices give indications of this
                      error/accuracy/uncertainty. </div>
                  </blockquote>
                  <div>The big advantage of the dualband is not (only)
                    the increase in accuracy but the ability to work in
                    not optimal conditions, like under a clif or other
                    obstacles where you have reflected GPS signals.</div>
                  <div><br>
                  </div>
                  <div>To give you an example, my eTrex device reports
                    3m of precision, the new GPSMAP 65s reports 1.8m.</div>
                  <div>But reality is that I saw errors up to 50m with
                    the eTrex. It's also difficult to know the precision
                    because it changes while moving, and it's not
                    recorded in the track.</div>
                  <blockquote class="gmail_quote" style="margin:0px 0px
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                    <div>
                      <p>If possible take tracks of home to/from work
                        and compare them to see how much they vary day
                        to day ... they should give an idea of problem.
                      </p>
                    </div>
                  </blockquote>
                  <div>I bought that new device exactly due the
                    frustration of always seeing a different
                    recording...</div>
                  <div><br>
                  </div>
                  <div>My initial tests are really encouraging.
                    Yesterday I repeated 10 times a trail under the
                    woods of a hill, comparing the results of the eTrex
                    and GPSMAP 65s, and the dualband one has the
                    recorded tracks a lot more consistent. Something
                    like 10m vs 2m thickness.</div>
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                    <blockquote class="gmail_quote" style="margin:0px
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                        <p>imagery may well be better than survey by
                          consumer GPS</p>
                      </div>
                    </blockquote>
                    <div>I agree. Where an image is available I always
                      use it as reference. But most of the trails of my
                      local area are under the woods (low mountain) and
                      the GPS is the only source of information.<br>
                    </div>
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