[Tagging] How to tag for dualband GPS ?

[Andrea Mazzoleni]

>
> 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:
> https://www.openstreetmap.org/user/bobwz/diary/394711
>
Very interesting!

Here you can find the mapping of my tests with GPSMAP 65s and eTrex 30x:

https://ibb.co/bKvpxYG

It's a circular trail repeated 5 times with one point every second.

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.

On Mon, Nov 30, 2020 at 3:45 PM Lindsay Barnes <newsspeak11 at gmail.com>
wrote:

> 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:
> https://www.openstreetmap.org/user/bobwz/diary/394711
>
> 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.
>
> 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.
>
> On Mon, Nov 30, 2020 at 8:36 AM Andrea Mazzoleni <amadvance at gmail.com>
> wrote:
>
>> On Mon, Nov 30, 2020 at 12:27 PM Warin <61sundowner at gmail.com> wrote:
>>
>>> 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.
>>>
>> 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.
>>
>> To give you an example, my eTrex device reports 3m of precision, the new
>> GPSMAP 65s reports 1.8m.
>> 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.
>>
>>> 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.
>>>
>> I bought that new device exactly due the frustration of always seeing a
>> different recording...
>>
>> 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.
>>
>>> imagery may well be better than survey by consumer GPS
>>>
>> 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.
>>
>> _______________________________________________
>> Tagging mailing list
>> Tagging at openstreetmap.org
>> https://lists.openstreetmap.org/listinfo/tagging
>>
> _______________________________________________
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>
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