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.vogelges...@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-boun...@lists.osgeo.org> on behalf of >>> Nicolas Cadieux <nicolas.cadi...@archeotec.ca> >>> *Sent:* 23 May 2020 16:34 >>> *To:* Randal Hale <rjh...@northrivergeographic.com> >>> *Cc:* qgis-user@lists.osgeo.org <qgis-user@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 >>> <rjh...@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 >>> <sack...@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 >>> _______________________________________________ >>> Qgis-user mailing list >>> Qgis-user@lists.osgeo.org >>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user >>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user >>> >>> _______________________________________________ >>> Qgis-user mailing list >>> Qgis-user@lists.osgeo.org >>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user >>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user >> _______________________________________________ >> Qgis-user mailing list >> Qgis-user@lists.osgeo.org >> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user >> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user > > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
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