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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi Henri,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I see in your description two base stations. One is with unknown position, let’s call it BaseA; and the other one is a permanent base station, let’s call it BaseB.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If I understand correctly, you are using the live broadcasting correction from BaseA to you Rover. And later on in rtkpost, you use BaseB as the base station.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I’m not sure if this is a proper way to do it, since this may mean you applied both corrections from BaseA and BaseB. Basically, you bring the multipath error, ionospheric and tropospheric errors from BaseB.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Can you try to apply correction from only one base station?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Regards,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Yanqing<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span lang=ZH-CN style='font-size:10.0pt;font-family:SimSun'>发件人</span></b><b><span style='font-size:10.0pt;font-family:SimSun'>:</span></b><span style='font-size:10.0pt;font-family:SimSun'> FOSS-GPS [mailto:foss-gps-bounces@lists.osgeo.org] <b><span lang=ZH-CN>代表 </span></b>henri Debise<br><b><span lang=ZH-CN>发送时间</span>:</b> Thursday, November 26, 2015 7:31 PM<br><b><span lang=ZH-CN>收件人</span>:</b> foss-gps@lists.osgeo.org<br><b><span lang=ZH-CN>主题</span>:</b> [FOSS-GPS] first steps with RTK and RTKPOST<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div id="yui_3_16_0_1_1448526636361_33021"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>Hello, <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_33018"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_33019"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>I'm new to the foss-gps list. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_33429"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>I come from France, so please excuse me if my English is not very good. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_37867"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_38954"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>I work in a small company which works with drone, the question of georeferencement is in our core business. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_42290"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>I'm currently studying the best choice to increase precision of gps track log. <br>So I'm studying results from PPP free service from canadian natural resources : </span><span lang=FR style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:black;mso-fareast-language:JA'><a href="http://webapp.geod.nrcan.gc.ca/geod/tools-outils/ppp.php?locale=fr" id="yui_3_16_0_1_1448526636361_50077"><span lang=EN-GB>http://webapp.geod.nrcan.gc.ca/geod/tools-outils/ppp.php?locale=en</span></a></span><span style='font-family:"Helvetica","sans-serif";color:black'><o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_42292"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>I'm also studying RTKLIB. My questions are mainly related to RTKLIB, but as GPS technology is quite new for me, I may misunderstood basic questions.<o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_54823"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_57032"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>On my test survey, we are using RTK mode: a base station in installed close to the drone (300 meters distance), and broadcasts live corrections to the drone which also has a GNSS antenna. The base is not installed on a known point, and we don't let the base a long time to increase the accurate of the base position. We use the base for 20 minutes only. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_72525"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>As the position of the base is not accurate, it is necessary to post process the GPS track log of the drone, then with RTKPOST<o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_153726"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_78045"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>As I'm in France, I've downloaded Rinex correction file from permanent GNSS station (<a href="http://rgp.ign.fr/DONNEES/diffusion/">http://rgp.ign.fr/DONNEES/diffusion/</a>). I've downloaded a file with a frequency of 1 second. I got observable and navigation file. Then I use RTKPOST from RTKLIB. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_92472"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>In field 'RINEX OBS : rover', I input my Rinex observable rover file (I don't use rtknavi). <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_94721"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>in field 'RINEX OBS : base station', I input the observable file from the permanent GNSS base station (rgp.ign). <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_96930"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>in field 'RINEX *NAV...' I input the navigation file from the permanent GNSS base station (rgp.ign). <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_99187"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>In options, Setting1 , I define the positioning mode to Kinematic. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_100335"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>Frequencies are L1+2, forward. Elevation mask is 10°. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_101470"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>in field Ionosphere correction, I tried 2 different inputs (without significant differences on the result) : Broadcast, and Iono-Free LC. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_104856"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>Troposphere correction is set to off and Satellite ephemeris/clock is set to broadcast. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_107102"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>I only work with GPS (5 or 6 satellites are available during the flight). <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_109330"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>I fill the coordinate of the permanent GNSS base station (rgp.ign) in Positions tab. I let all the other input to default. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_111558"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>Then I execute. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_112673"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>different things about the results : <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_112675"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>- the quality flag, Q, is set to 5: Single, solution by single point positioning. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_116036"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>Shouldn't it be equal to 1 or 2 ? <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_117141"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>- I wonder why, in the input of the rinex observable file, we can't select many files ? (same question for rinex navigation file)<o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_121597"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>I mean, I can have many files, each one from a different permanent GNSS base station. Do I have to merge those files before processing in RTKPOST ? <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_127109"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>- In my results, I get a gap of around 5 meters, in comparison to my RTK gps track log without post processing. This looks to me as a very important gap. I can't say if the result is better, but is it possible to get a so important gap between RTK with and without postprocessing? In my rinex observable file from the rover , I had 1 and 1 for WAVELENGTH FACT L1/2, that's enough to ensure RTK mode had really worked ? <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_137103"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>- Also I have noise, on the post processed track log. Small noise : around 10 cm for 0.3 second for example, but this noise does'nt exist on my RTK gps track log without post processing. And the change of ionosphere correction to Iono-Free LC didn't successed to remove the noise. How can I remove the noise ? <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_142646"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_148171"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>I heard that PPP solution is not suitable for my configuration as the solution as no time to convert, the flight is too short. If you have any comments about this, there are welcome. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_148174"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_148173"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>Thank you for your attention, I hope to read soon any comments/suggestions/.... <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_152595"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_152593"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>Henri <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_148178"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_133769"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_124909"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_99188"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_92460"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_62569"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1448526636361_64783"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div></div></div></body></html>