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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 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"'> foss-gps-bounces@lists.osgeo.org [mailto:foss-gps-bounces@lists.osgeo.org] <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></body></html>