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

Sat May 23 12:53:05 PDT 2020

If you don't want to attempt to engineer your own GNSS hardware + software,
you may want to check out the Bad Elf GNSS Surveyor. Yes, it's in the
neighborhood of $500 US, but gives relatively consistent positions within
about 1 meter with averaging, its data can be differentially
corrected using the RTKLIB open-source software, and if you are working in
an area with cell service, it can receive real-time corrections via NTRIP
networks if this is available in your area (it is here in Michigan). Some
Googling will turn up tutorials. I have done some simple comparisons with
Trimble hardware and have been pleased with the results.

Best,
Mike

On Sat, May 23, 2020 at 3:45 PM <j.huber at post-ist-da.de> wrote:

> 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>
> <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>
> <qgis-user-bounces at lists.osgeo.org> on behalf of Nicolas Cadieux
> <nicolas.cadieux at archeotec.ca> <nicolas.cadieux at archeotec.ca>
> *Sent:* 23 May 2020 16:34
> *To:* Randal Hale <rjhale at northrivergeographic.com>
> <rjhale at northrivergeographic.com>
> *Cc:* qgis-user at lists.osgeo.org <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>
> <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>
> <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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