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.
Maybe it will work if you change the standard deviations of the observations. Kind regards, Yanqing > On 18 Sep 2014, at 14:16, "Sean Hyde" <[email protected]> wrote: > > Hi Antonio, > > 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. > > The base station and the rover are much closer than 100m. > > -Sean > > From: [email protected] > [mailto:[email protected]] On Behalf Of António Pestana > Sent: Thursday, September 18, 2014 4:06 AM > To: Open Source GPS-related discussion and support > Subject: Re: [FOSS-GPS] Mobile Robot Experimentation > > 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. > > Antonio > > 2014-09-18 8:50 GMT+01:00 Yanqing <[email protected]>: > Dual frequency receivers could solve this problem. You need both the rover > and the base station receivers to be dual frequency. > > Kind regards, > Yanqing > > On 18 Sep 2014, at 03:02, "Sean Hyde" <[email protected]> wrote: > > 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. > > “I'm not sure what receivers you are using, but if it's this one: > http://www.nvs-gnss.com/products/receivers/item/2-nv08c-csm.html it seems > to be L1 only, not L1+L2. The antenna you are using covers 1574-1610 MHz, > so while multi-system (GPS/Glonass) it is also L1 only. The GPS L2 > frequency is quite a bit lower, at 1227.6 MHz. > http://en.wikipedia.org/wiki/GPS_signals#Frequencies_used_by_GPS > > As far as I know, GPS L1+L2 receivers start around $750 used (eg. Trimble > 4000ssi on ebay) and much more new. > “ > > 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? > > > “Did you try with simultaneous mode of ambiguity resolution and use a smaller > min ratio to fix ambiguity, such as 2 or 1.5? > > Kind regards, > Yanqing > “ > > 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. > > -Sean > _______________________________________________ > This message is sent to you from [email protected] mailing list. > Visit http://lists.osgeo.org/mailman/listinfo/foss-gps to manage your > subscription > For more information, check http://wiki.osgeo.org/wiki/FOSS-GPS > > _______________________________________________ > This message is sent to you from [email protected] mailing list. > Visit http://lists.osgeo.org/mailman/listinfo/foss-gps to manage your > subscription > For more information, check http://wiki.osgeo.org/wiki/FOSS-GPS > > _______________________________________________ > This message is sent to you from [email protected] mailing list. > Visit http://lists.osgeo.org/mailman/listinfo/foss-gps to manage your > subscription > For more information, check http://wiki.osgeo.org/wiki/FOSS-GPS
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