Dear Thomas: > Who is the manufacturer of your GPS equipment that you used to collect the > Rinex data?
AS10 antennas, GMX 902 GNSS receptors and software GNSS Spider, everything from Leica. I want do the tests in real-world situations, and I already have one that set that spans for two months at 20 MHz, almost without interruptions. > Please define ‘very demanding’ in terms of horizontal and vertical > accuracy requirements We want to test GNSS near real-time positioning techniques in the monitoring of large structures (mainly bridges and tall buildings). Better than 1 cm is mandatory; better than 0.5 cm is what I would like to get. Our baselines are not long: usually less than 2 km. We want near real-time (real-time with a constant, and small, time delay) because we want to plot the behavior of the structures under dynamic loads. > RTK by it’s very nature does not utilize a intermediate PC. The GMX 902 receptors are just dummy receptors: they don't have processing capacity apart from the one that is needed to get the code and phase observations. So we need PC's to do the configuration of the receptors (elevation mask, rate of observations, etc.), defining the data to be logged if any (and the formats to use) end do the positioning computations. In my setup I used a PC for each receptor. I could not do the displacement analysis in real-time using Spider because I could not connect both rover and reference to the same PC running Spider. That's why I decided to store the observations (rover and reference) in RINEX files. No I want do process these files as if they were being collected just now. > The rover applies a correcting factor that was developed by the base and > broadcast in some fashion. I am aware of these techniques mostly used in large-area RTK network for GIS and Surveying. The observations made by the reference stations belonging to the network are used to build model of the errors for all the area of the network. Then there are two main "ways of doing the things": a) the rover sends is approximate position to the network and the network returns to the rover the corrections computed for the position of the rover; b) the network sends to the rover the parameters of the error model and the rover computes the actual values to his position. Given that my baselines are small I think that in my case the best approach is to use plain-old double-differences. As you stated the use of ionospheric-free combination of observations may prove to be disadvantageous (theoretically these linear combinations have the potential to increase the noise): clearly this is one aspect that needs to be tested. But I need to get one position for epoch, that is to say, I want to get positions at a 20 MHz rate. > To answer your question, the processing software that come with your GPS > units should be able to do the work depending on the features that were > licensed with it Yes, Spider could to the job. But as I have already written it needs to be connected to the two receivers at the same time. This connection proved to be impossible in site. Regards Antonio -- View this message in context: http://open-source-gps-related-discussion-and-support.1099874.n2.nabble.com/Post-processing-RINEX-to-simulate-RTK-tp6926010p6932334.html Sent from the Open Source GPS-related discussion and support mailing list archive at Nabble.com. _______________________________________________ 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
