<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>If the baseline is less than 100 meters, it is definitely not needed to consider the ionospheric delay. I guess the error source may be from different multipath for the two receivers.</div><div><br></div><div>Maybe it will work if you change the standard deviations of the observations. <br><br>Kind regards,<div>Yanqing</div></div><div><br>On 18 Sep 2014, at 14:16, "Sean Hyde" <<a href="mailto:sean.a.hyde@gmail.com">sean.a.hyde@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><meta name="Generator" content="Microsoft Word 15 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--><div class="WordSection1"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi Antonio,<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">I’m glad to hear you say this as the NV08C manufacturer makes a big deal of using this module to do this using RTKLIB and I was getting worried.<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">The base station and the rover are much closer than 100m.<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">-Sean<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"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> <a href="mailto:foss-gps-bounces@lists.osgeo.org">foss-gps-bounces@lists.osgeo.org</a> [<a href="mailto:foss-gps-bounces@lists.osgeo.org">mailto:foss-gps-bounces@lists.osgeo.org</a>] <b>On Behalf Of </b>António Pestana<br><b>Sent:</b> Thursday, September 18, 2014 4:06 AM<br><b>To:</b> Open Source GPS-related discussion and support<br><b>Subject:</b> Re: [FOSS-GPS] Mobile Robot Experimentation<o:p></o:p></span></p><p class="MsoNormal"><o:p> </o:p></p><div><p class="MsoNormal">If rover and base are close enough (say, no more than a few hundred meters apart) ionospheric refraction pseudoranges disturbances will be pretty much the same both for base and rover. Therefore mono-frequency observations will suffice.<o:p></o:p></p><div><p class="MsoNormal"><o:p> </o:p></p></div><div><p class="MsoNormal">Antonio<o:p></o:p></p></div></div><div><p class="MsoNormal"><o:p> </o:p></p><div><p class="MsoNormal">2014-09-18 8:50 GMT+01:00 Yanqing <<a href="mailto:fishloveocean@gmail.com" target="_blank">fishloveocean@gmail.com</a>>:<o:p></o:p></p><blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in"><div><div><p class="MsoNormal">Dual frequency receivers could solve this problem. You need both the rover and the base station receivers to be dual frequency.<br><br>Kind regards,<o:p></o:p></p><div><p class="MsoNormal">Yanqing<o:p></o:p></p></div></div><div><div><div><p class="MsoNormal" style="margin-bottom:12.0pt"><br>On 18 Sep 2014, at 03:02, "Sean Hyde" <<a href="mailto:sean.a.hyde@gmail.com" target="_blank">sean.a.hyde@gmail.com</a>> wrote:<o:p></o:p></p></div><blockquote style="margin-top:5.0pt;margin-bottom:5.0pt"><div><div><p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Thanks for the responses! I apologize for breaking the thread, but I had turned on Digests by accident and couldn’t figure out how to reply to individual messages.<o:p></o:p></p><p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p><pre>“<span style="color:black">I'm not sure what receivers you are using, but if it's this one: </span><o:p></o:p></pre><pre><span style="color:black"><a href="http://www.nvs-gnss.com/products/receivers/item/2-nv08c-csm.html" target="_blank">http://www.nvs-gnss.com/products/receivers/item/2-nv08c-csm.html</a> it seems </span><o:p></o:p></pre><pre><span style="color:black">to be L1 only, not L1+L2. The antenna you are using covers 1574-1610 MHz, </span><o:p></o:p></pre><pre><span style="color:black">so while multi-system (GPS/Glonass) it is also L1 only. The GPS L2 </span><o:p></o:p></pre><pre><span style="color:black">frequency is quite a bit lower, at 1227.6 MHz.</span><o:p></o:p></pre><pre><span style="color:black"><a href="http://en.wikipedia.org/wiki/GPS_signals#Frequencies_used_by_GPS" target="_blank">http://en.wikipedia.org/wiki/GPS_signals#Frequencies_used_by_GPS</a></span><o:p></o:p></pre><pre><span style="color:black"> </span><o:p></o:p></pre><pre><span style="color:black">As far as I know, GPS L1+L2 receivers start around $750 used (eg. Trimble </span><o:p></o:p></pre><pre><span style="color:black">4000ssi on ebay) and much more new.</span><o:p></o:p></pre><p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">“<o:p></o:p></p><p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p><p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi John. I had completely overlooked the fact that the NV08C couldn’t utilize L2 as I had read a lot of information about using it in RTK setups. I’m rather new to GPS. My understanding is that without L2 I will not be able to get rid of ionospheric delay, which will increase error. Could this be why my system isn’t performing as I hoped? Can I get away with using an L1+L2 receiver on the Base Station and not on the Rover?<o:p></o:p></p><p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p><p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p><pre>“<span style="color:black">Did you try with simultaneous mode of ambiguity resolution and use a smaller min ratio to fix ambiguity, such as 2 or 1.5?</span><o:p></o:p></pre><pre><span style="color:black"> </span><o:p></o:p></pre><pre><span style="color:black">Kind regards,</span><o:p></o:p></pre><pre><span style="color:black">Yanqing</span><o:p></o:p></pre><p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">“<o:p></o:p></p><p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p><p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hello Yanging. I tried instantaneous mode and it seemed much worse. My Float solutions oscillated by several meters (instead of a tens of centimeters with a drift) and I couldn’t get a Fix. I tried reducing the ratio in the other modes. Although that got me a fix more easily, I was concerned that it wasn’t accurate, as it was not repeatable. <o:p></o:p></p><p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p><p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">-Sean<o:p></o:p></p></div></div></blockquote></div></div><blockquote style="margin-top:5.0pt;margin-bottom:5.0pt"><div><p class="MsoNormal">_______________________________________________<br>This message is sent to you from <a href="mailto:FOSS-GPS@lists.osgeo.org" target="_blank">FOSS-GPS@lists.osgeo.org</a> mailing list.<br>Visit <a href="http://lists.osgeo.org/mailman/listinfo/foss-gps" target="_blank">http://lists.osgeo.org/mailman/listinfo/foss-gps</a> to manage your subscription<br>For more information, check <a href="http://wiki.osgeo.org/wiki/FOSS-GPS" target="_blank">http://wiki.osgeo.org/wiki/FOSS-GPS</a><o:p></o:p></p></div></blockquote></div><p class="MsoNormal"><br>_______________________________________________<br>This message is sent to you from <a href="mailto:FOSS-GPS@lists.osgeo.org">FOSS-GPS@lists.osgeo.org</a> mailing list.<br>Visit <a href="http://lists.osgeo.org/mailman/listinfo/foss-gps" target="_blank">http://lists.osgeo.org/mailman/listinfo/foss-gps</a> to manage your subscription<br>For more information, check <a href="http://wiki.osgeo.org/wiki/FOSS-GPS" target="_blank">http://wiki.osgeo.org/wiki/FOSS-GPS</a><o:p></o:p></p></blockquote></div><p class="MsoNormal"><o:p> </o:p></p></div></div></div></blockquote><blockquote type="cite"><div><span>_______________________________________________</span><br><span>This message is sent to you from <a href="mailto:FOSS-GPS@lists.osgeo.org">FOSS-GPS@lists.osgeo.org</a> mailing list.</span><br><span>Visit <a href="http://lists.osgeo.org/mailman/listinfo/foss-gps">http://lists.osgeo.org/mailman/listinfo/foss-gps</a> to manage your subscription</span><br><span>For more information, check <a href="http://wiki.osgeo.org/wiki/FOSS-GPS">http://wiki.osgeo.org/wiki/FOSS-GPS</a></span></div></blockquote></body></html>