<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body dir="auto"><div dir="auto">Hi Springer.</div><div dir="auto"><br></div><div dir="auto">Have fun and your questions stimulated a good discussion and ideas.</div><div dir="auto"><br></div><div dir="auto">If you are collecting gps data on the clock, I would seriously consider installing a ground plane on your range pole. This will eliminate zingers and you can reduce your observation time. A electrical junction box cover works well.</div><div dir="auto"><br></div><div dir="auto">Waas currently is good to 0.9 m horizontal and 1.3 m vertical 95% of the time. It helps but is not a stand alone solution for high precision work.</div><div dir="auto"><br></div><div dir="auto">Kirk Schmidt</div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div id="composer_signature" dir="auto"><div style="font-size:85%;color:#575757" dir="auto">Sent from my Galaxy</div></div><div dir="auto"><br></div><div><br></div><div align="left" dir="auto" style="font-size:100%;color:#000000"><div>-------- Original message --------</div><div>From: Springfield Harrison <stellargps@gmail.com> </div><div>Date: 2021-03-10 4:30 a.m. (GMT-04:00) </div><div>To: Kirk Schmidt <kirk@nortekresources.com>, qgis-user@lists.osgeo.org </div><div>Subject: Re: [Qgis-user] Trimble GeoXT 2005 Accuracy </div><div><br></div></div>Hi Kirk,<br><br>OK, I'll rule out the PPP for now, although it doesn't seem to be <br>practical for production mapping anyway.<br><br>I think my antennas are probably OK, none of them have a ground plane, <br>not practical for field mapping. I've only seen them in geodetic <br>applications. Of course, the aircraft installation is free of multipath <br>except while on the ground. Longer observing periods should minimize <br>the impact of multipath zingers.<br><br>The tight clustering of the GeoXT points in Map A doesn't smell of <br>multipath to me.<br><br>Earlier you noted the possibility of antenna shielding by the operator. <br>With that in mind, I use a tripod or a range pole with the antenna above <br>head height. WAAS is actually quite accurate, good for certain (lower <br>order?) precision approaches.<br><br>I'm still digesting all this helpful feedback and will work on a summary <br>shortly. Thanks again . . . .<br><br>-----<br>Cheers, Spring<br><br><br><br>On 09/Mar/2021 12:14, Kirk Schmidt wrote:<br>> Hi Springfield:<br>><br>> PPP requires long observation times in the order of hours and <br>> therefore a new field survey. I would try post processing from a high <br>> precision site with your existing data.<br>><br>> Another issue may be the aviation antennae you mentioned. These are <br>> usually mounted on the top of a fuselage and therefore the aluminum <br>> acts as a ground plane to effectively filter out multipath. If you <br>> use a metal disk or plate and a ground plane on your antennae and <br>> mount it on a tripod, you may find you end up with better results. <br>> You will notice survey grade antennae's have a large diameter plastic <br>> case since the contain an internal 10 cm metal disk.<br>><br>> Kirk Schmidt<br>><br>> On 3/9/2021 1:36 PM, Springfield Harrison wrote:<br>>> Hello Garth,<br>>><br>>> Thanks very much for that reference. I have used the service in the <br>>> past.<br>>><br>>> I'm in the middle of other work but may try to re-process some Map A <br>>> files using PPP to see what changes.<br>>><br>>> Your work sounds more like surveying than mapping, interesting.<br>>><br>>> I do use the GPS reception planning tools but SV availability is <br>>> certainly better than in the early days.<br>>><br>>> Thanks again . . . .<br>>><br>>> -----<br>>> Cheers, Spring<br>>><br>>><br>>><br>>> On 09/Mar/2021 09:01, Garth Fletcher wrote:<br>>>> Nicolas Cadieux wrote:<br>>>>> Kirk could be on the right track. You could try PPP using this <br>>>>> site. You will need to create a user name and password. Then, you <br>>>>> upload the Rinex file. I am 99% sure you can process point from <br>>>>> outside of Canada. <br>>>><br>>>> I routinely use CSRS PPP to post process RINEX files from Southern New<br>>>> Hampshire (43°N, 72°W).<br>>>><br>>>> Using an iGage iG3s (L1/L2 dual frequency, GPS + GLONASS) recording at<br>>>> 5 second epochs in forested areas, from post processing I get<br>>>> 30 minute recordings, 95% error ellipses < 1 meter<br>>>> 10 hour recordings, 95% error ellipses < 2 cm<br>>>><br>>>> CSRS-PPP site is<br>>>> <https://webapp.geod.nrcan.gc.ca/geod/tools-outils/ppp.php?locale=en><br>>>> enter your email address<br>>>> select Static and which NAD 83 epoch you want, or ITRF<br>>>> Submit a RINEX file (.zip compressing the file is encouraged)<br>>>> they will email back a detailed report<br>>>><br>>>> You can submit for 1 of 3 levels of post processing<br>>>> ultra-rapid : submit > 90 minutes after end of recording<br>>>> rapid: submit > 24 hours after end of recording<br>>>> final: submit ~ 3 weeks after end of recording<br>>>><br>>>> Major part of corrections are in ultra-rapid, the higher levels provide<br>>>> further refinements.<br>>>><br>>>><br>>>> FYI: Trimble provides occupation planning aids at<br>>>> <https://www.gnssplanning.com/#/charts><br>>>> just enter your location and date and it shows you the DOP as<br>>>> a function of the hour of day.<br>>>><br>>>> Cordially,<br>>> _______________________________________________<br>>> Qgis-user mailing list<br>>> Qgis-user@lists.osgeo.org<br>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user<br>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user<br>><br><br></body></html>