[Qgis-user] wishing for accurate lattitude/longitude from a cell phone

Sat May 23 12:45:31 PDT 2020

Hi Nicolas,

there are several potentially accurate GNSS modules available, even
sensitive choke ring antennas aren't that expensive. What's time
consuming and difficult is building a whole functioning system
(integration and software).
This would be a great university project - develop an open source GNSS
system based on relatively unexpensive components. It should be possible
to get the cost down from over a thousand to several hundred euro. This
could also be the basis for a "free" correction data service built on
private reference stations. Just dreaming...

I agree that for precision, "old school" technology is often better and
cheaper, although it requires more effort than simply pushing a button.

Regards
Jochen

Am 23.05.20 um 20:21 schrieb Nicolas Cadieux:
> Hi,
>
> I looked at the page.It looks like a neat project!  Buy time you buy a
> case, antenna... (I don’t think they come with on), your back into the
> price range of a forestry grade survey GPS unit.  I think the Emild
> single band gps (https://emlid.com/reachrs/ 
> <https://emlid.com/reachrs/>) is probably a better choice unless you
> really want to make this a learning project. But if I understand you
> are really on a shoe string budget.
>
> None of these Gps, by the way, would beat and old theodolite...  if
> you can establish or find a good gps position (look for the city or
> state geomatics services) or survey point,  a théodolite would give
> you survey grade positions.  City have these points on every few
> blocks.  You may be able to find A theodolite for free.  A second hand
> TotalStation could be better but that will be more difficult to find
> in those price ranges (Shoe string).  You can also rent equipment or
> find a college that would take this up as a teaching opportunity.
>
> Have fun!
>
> Nicolas Cadieux
> Ça va bien aller!
>
>> Le 23 mai 2020 à 13:52, Bernd Vogelgesang <bernd.vogelgesang at gmx.de>
>> a écrit :
>>
>> 
>>
>> Unfortunately, the Forest Service Website went offline (maybe this
>> thread caused so much traffic that it broke down? ;) )
>>
>> I'm also desperately searching for an affordable way to have at least
>> some decent accuracy. I do not need submeter, but it would be
>> fantastic if it was possible to achieve meter accuracy.
>> I gave up on that Garmin stuff. They might be accurate, but I have no
>> chance to control this until I return home and put the recorded data
>> on screen over an aerial image. Those screens are a joke, and the
>> business logic that prevents me to put reasonable aerial imagery on
>> the device without paying a fortune is apita. Maybe this improved
>> cause I last checked 5 years ago.
>>
>> Mobile phones at least in my case seem to get worse. My Motorola from
>> 2016 had an accuracy of less than 4 meters, most of the time less than 2.
>> Now I bought a Huawei 30 pro cause of the camera (my first phone with
>> nice pictures!), but the accuracy is a nightmare. The position is
>> jumping around like a dog on rabies.
>> I also bought a bluetooth device (Navilock BT-821G) two years ago.
>> This is much better than the phones GPS, tho it only receives 20
>> satellites maximum (The phone claims to receive some 40). But also
>> this device sometimes, when walking a transect, is constantly 5
>> meters off the track for several several minutes.
>>
>> As apps averaging the positions were mentioned: Does anyone have a
>> recommendation on such apps (for Android)? I found some, but the
>> usability was not that great, and some even didn't enhance anything.
>>
>> Furthermore, I stumble upon an article about a module with u-blox
>> chip. https://www.sparkfun.com/products/16481
>> Does anyone have any experience with modules like this and what else
>> is needed? The description of all the stuff leaves me a bit puzzled.
>>
>> Cheers,
>>
>> Bernd
>>
>> On 23.05.20 18:17, Michael.Dodd wrote:
>>> https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.2041-210X.2011.00118.x
>>> I did this quite a few years ago but in the graph in supplimentary
>>> material it shows how the accuracy of one consumer grade gps varies
>>> over time (at a fixed point). At the time I also did a lot more
>>> measurements using mobile phones and consumer grade units on a grid
>>> of points in the field, that was not published but basically the
>>> phones were often as good as if not better than the consumer grade
>>> gps units especially when using certain apps to average points.
>>> <https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.2041-210X.2011.00118.x>
>>> 	
>>> Where are my quadrats? Positional accuracy in fieldwork - Dodd -
>>> 2011 - Methods in Ecology and Evolution - Wiley Online Library
>>> <https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.2041-210X.2011.00118.x>
>>> Introduction. There has been much written about sampling design,
>>> spatial scale and the need for permanent plots in ecological
>>> long‐term monitoring, for example, the paper on spatial scaling in
>>> ecology has been cited over 1500 times, but one frequently ignored
>>> issue, intimately associated with sampling design, scale and
>>> permanence of plots, is how to locate positions accurately.
>>> besjournals.onlinelibrary.wiley.com
>>>
>>>
>>> ------------------------------------------------------------------------
>>> *From:* Qgis-user <qgis-user-bounces at lists.osgeo.org> on behalf of
>>> Nicolas Cadieux <nicolas.cadieux at archeotec.ca>
>>> *Sent:* 23 May 2020 16:34
>>> *To:* Randal Hale <rjhale at northrivergeographic.com>
>>> *Cc:* qgis-user at lists.osgeo.org <qgis-user at lists.osgeo.org>
>>> *Subject:* Re: [Qgis-user] wishing for accurate lattitude/longitude
>>> from a cell phone
>>>  
>>> CAUTION: This mail comes from outside the University. Please
>>> consider this before opening attachments, clicking links, or acting
>>> on the content.
>>>
>>> Hi,
>>>
>>> This is a very interesting list. It basically confirms what I
>>> thought. Consumer Point and shoot deceives are all around 2-6m with
>>> no canopy. The average multiple positions basically give you a
>>> better idea as a gps may get lucky.  It would be nice to have the
>>> full methodology for this and more data (like the number of
>>> satellite and the position of the constellation and the gps price
>>> list) but it’s very interesting none the less.  I was also happy
>>> that the data confirms the precision of the gps Sx-Blue 11. This
>>> claims to be sub meter and my tests indicated that on our office
>>> unit but it’s nice to see it done elsewhere.  For about 2000$, this
>>> gps is pretty good. As for the rest, the difference between 150$ and
>>> 1000$ is probably  more a function of the options (like maps and
>>> screen size...) and not a question of precision. It would be nice to
>>> know what gps chips they are running...
>>>
>>> Interesting thing also is that based on my reviewing the data on my
>>> phone (without graph or cross tabulation tables) is that the Glonas
>>> Constellation does not seem to help much.  Quick stats on this list
>>> would confirm this. Maybe this is just a figment of my imagination
>>> because there’s only so much information you can grad without
>>> running proper stats.
>>>
>>> Thanks for the post.
>>>
>>> Nicolas Cadieux
>>> Ça va bien aller!
>>>
>>> > Le 23 mai 2020 à 09:02, Randal Hale
>>> <rjhale at northrivergeographic.com> a écrit :
>>> >
>>> > One other thing that may or may not be of use but the USDA Forest
>>> Service Publishes a GPS Receiver Report that covers phones - and
>>> that's helped if I've had a client go "Well I have a Apple
>>> <something> or a Android <thing>". At least I feel slightly better
>>> going "good enough" or "no not good enough".
>>> >
>>> > It should be good worldwide (but I will admit I think phones are
>>> my 'tech ceiling' these days) but your mileage may vary.
>>> >
>>> > https://www.fs.fed.us/database/gps/mtdcrept/accuracy/index.htm
>>> >
>>> > Randy
>>> >
>>> >> On 5/22/20 8:55 PM, Priv.-Doz. Dr. Maria Shinoto wrote:
>>> >> Somehow I did not follow the discussion, but like to add some of
>>> our experience.
>>> >>
>>> >> We are doing field work in a remote region in the southern
>>> Japanese mountains, archaeological surveys on the ground based on
>>> LiDAR data.
>>> >>
>>> >> A simple Garmin etrex10 is mostly reliable in an area of 40cm by
>>> 40cm around a measured point, if used repeatedly at this point and
>>> the point is located in the middle of a valley. Even cell phones do
>>> a good enough job. As soon as we get closer to the steep slopes, the
>>> accuracy of the Garmin is less than 5 to 10 meters. We can check
>>> this with the detailed LiDAR based map, and geologists told us, that
>>> even an expensive device could not be more precise under these
>>> conditions. So we decided to measure traditionally on the ground if
>>> precise measure is necessary, otherwise note the GPS data and the
>>> location as shown in the map.
>>> >>
>>> >> To sum up, we came to the conclusion not to spend money on an
>>> expensive GPS that may not work in the shadow of steep slopes -- or
>>> in the streets of New York. -- I appreciate any additional advice,
>>> and hope that this experience can save Steve's organisation some
>>> money...
>>> >>
>>> >> Best,
>>> >> Maria
>>> >>
>>> >>
>>> >>
>>> >>>> Am 23.05.2020 um 03:54 schrieb Stephen Sacks
>>> <sacks44 at earthlink.net>:
>>> >>>
>>> >>> In order to make widely available some wise advice, I'm sending
>>> to this list a message I received from Neil B.  In addition to
>>> Neil's message below, I want to mention that Nicolas Cadieux also
>>> provided similar information, saying I'd have to pay around $1,000
>>> for equipment that gives consistently accurate location
>>> coordinates.  And thanks, also to Falk Huettmann and Bernd
>>> Vogelgesang for their replies.
>>> >>>
>>> >>>
>>> >>> Message from Neil B:
>>> >>>
>>> >>> Hello Stephen.
>>> >>> Glad that you're having su
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