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 <[email protected]> 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 <[email protected]> > <[email protected]> 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 <[email protected]> > <[email protected]> on behalf of Nicolas Cadieux > <[email protected]> <[email protected]> > *Sent:* 23 May 2020 16:34 > *To:* Randal Hale <[email protected]> > <[email protected]> > *Cc:* [email protected] <[email protected]> > <[email protected]> > *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 <[email protected]> > <[email protected]> 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 <[email protected]> > <[email protected]>: > >>> > >>> 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 > [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user > > _______________________________________________ > Qgis-user mailing [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user > > _______________________________________________ > Qgis-user mailing list > [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user > > > _______________________________________________ > Qgis-user mailing [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user > > > _______________________________________________ > Qgis-user mailing list > [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
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