MediaWiki API result

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            "*": "Subscribe to the mediawiki-api-announce mailing list at <https://lists.wikimedia.org/postorius/lists/mediawiki-api-announce.lists.wikimedia.org/> for notice of API deprecations and breaking changes."
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            "*": "Because \"rvslots\" was not specified, a legacy format has been used for the output. This format is deprecated, and in the future the new format will always be used."
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        "pages": {
            "969": {
                "pageid": 969,
                "ns": 0,
                "title": "Real Time Kinematics",
                "revisions": [
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                        "*": "{{Article Infobox2\n|Category=Fundamentals\n|Editors=GMV\n|Level=Basic\n|YearOfPublication=2011\n|Logo=GMV\n|Title={{PAGENAME}}\n}}\nWith origin dating back to the mid-1990s, Real Time Kinematics (RTK) is a [[Differential GNSS|differential GNSS]] technique which provides high positioning performance in the vicinity of a base station. The technique is based on the use of carrier measurements and the transmission of corrections from the base station, whose location is well known, to the rover, so that the main errors that drive the stand-alone positioning cancel out. A RTK base station covers a service area spreading about 10 or 20 kilometres, and a real time communication channel is needed connecting base and rover. RTK, which achieves performances in the range of a few centimetres, is a technique commonly used in surveying applications.<ref name=\"RTKIAG\">[http://www.wasoft.de/e/iagwg451/ International Association of Geodesy (IAG) Working Group 4.5.1: Network RTK ] </ref><ref name=\"RTK_WIKI\">[http://en.wikipedia.org/wiki/Real_Time_Kinematic RTK in Wikipedia]</ref><ref name=\"RTKWPNC06\">[http://www.wpnc.net/fileadmin/WPNC06/Proceedings/34_Precise_Positioning_in_Real-Time_using_Navigation_Satellites_and.pdf Remote Sensing 2009, A. Rietdorf et al., ''Precise Positioning in Real-Time using Navigation Satellites and Telecommunication'', Proceedings of the 3rd Workshop on Positioning, Navigation and Communication (WPNC\u201906) ]</ref>\n\n==Introduction RTK==\nReal Time Kinematics (RTK) is a [[Differential GNSS|differential GNSS]] technique originated in the mid-1990s that provides high performance positioning in the vicinity of a base station.<ref name=\"RTKIAG\"/>\n\nFrom an architectural point of view, RTK consists of a base station, one or several rover users, and a communication channel with which the base broadcasts information to the users at real time.\n\n[[File:Summit_rtk_survey.jpg|300px|thumb|RTK Support Polar Survey]]\n\nThe technique is based on the following high-level principles:\n*In the neighbourhood of a clean-sky location, the main errors in the GNSS signal processing are constant, and hence they cancel out when differential processing is used. This includes the error in the satellite clock bias, the satellite orbital error, the ionospheric delay and the tropospheric delay.\n*The noise of carrier measurements is much smaller than the one of the pseudo-code measurements. However, the processing of carrier measurements is subject to the so-called carrier phase ambiguity, an unknown integer number of times the carrier wave length, that needs to be fixed in order to rebuild full range measurements from carrier ones.\n*The phase ambiguity can be [[RTK Fundamentals|fixed]] for dual-frequency differential measurements for two close receivers.\n\nThe base station broadcasts its well-known location together with the code and carrier measurements at frequencies L1 and L2 for all in-view satellites. With this information, the rover equipment is able to fix the phase ambiguities and determine its location relative to the base with high precision. By adding up the location of the base, the rover is positioned in a global coordinate framework.\n\nThe RTK technique can be used for distances of up to 10 or 20 kilometres,<ref name=\"RTKIAG\"/><ref name=\"RTKWPNC06\"/> yielding accuracies of a few centimetres in the rover position. RTK is extensively used in surveying applications.\n\nThe main limitations of RTK are as follows:\n*Limited range with respect to the base location.\n*The need of a communication channel for real time applications.\n*Some convergence time is needed to fix the phase ambiguities. This time depends on the processing algorithm and the distance between base and rover, and ranges from a few seconds to a few minutes.\n*In order to avoid re-initialization of the processing, the rover has to track the GNSS signals continuously. This makes the RTK not suitable for urban applications.\n\nRecently, different approaches have been followed to improve the limitation regarding the range of the base station, namely Network RTK<ref name=\"RTKIAG\"/><ref name=\"RTCM_V3\">[http://www.rtcm.org/ RTCM STANDARD 10403.1, FOR DIFFERENTIAL GNSS (GLOBAL NAVIGATION SATELLITE SYSTEMS) SERVICES \u2013 VERSION 3, RTCM 10403.1, RTCM Paper 177-2006-SC104-STD, 2006]</ref> and [[Wide Area RTK (WARTK)|Wide Area Real Time Kinematics (WARTK)]]. Network RTK is based on the provision of corrections from a network of base stations in such a way that the phase measurements are provided with consistent ambiguities; this has the advantage that the rover can switch from one base station to another without the need of re-initializing the ambiguity fixing filters. WARTK is further described in dedicated [[Wide Area RTK (WARTK)|articles]].\n\n==RTK Related Articles==\n\nThe following articles include further information about different important topics related to RTK:\n* [[RTK Fundamentals|RTK Fundamentals]]. \n* [[RTK Standards|RTK Standards]].\n* [[RTK Systems|RTK Systems]].\n\n\n==Notes==\n<references group=\"footnotes\"/>\n\n==References==\n<references/>\n\n[[Category:Fundamentals]]"
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            "597": {
                "pageid": 597,
                "ns": 0,
                "title": "Receiver Antenna Phase Centre",
                "revisions": [
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                        "*": "{{Article Infobox2\n|Category=Fundamentals\n|Authors=J. Sanz Subirana, J.M. Juan Zornoza and M. Hern\u00e1ndez-Pajares, Technical University of Catalonia, Spain.\n|Level=Basic\n|YearOfPublication=2011\n|Title={{PAGENAME}}\n}}\nThe measurements are referred to the [[Antenna Phase Centre]] (APC) position. As this location is frequency dependent, a point tied to the base of the antenna is used as a more suitable reference. This point is named Antenna Reference Point (ARP). The manufacturers provide technical information on the APC position relative to the ARP. On the other hand, relative and absolute antenna phase centre corrections have been compiled by IGS and are provided in the PCV and ANTEX files respectively for several antenna models (see [[Antenna Phase Centre]]).\n\nIn geodetic positioning, the receiver coordinates are referred to a Monument Marker (MM) or to an external Benchmark (BM). Figure 1 illustrates this concept.\n\n\n::[[File:Rx_APC_ STAOFF.png|none|thumb|520px|'''''Figure 1:''''' Layout of a permanent receiver site with indication of the Monument Marker, Antenna Reference Point and Antenna Phase Centre.]]\n\n\nIn the IGS SINEX files, the computed coordinates for Monument Marker coordinates are given in the block \"SOLUTION/ESTIMATE\", in ECEF coordinates, for each processed station. The position of the ARP relative to the MM, or the site eccentricity vector, are given the block \"SITE/ECCENTRICITY\" in Up North East (UNE) coordinates. Finally, the Antenna Phase Centre offsets for the different frequencies used and the Antenna Calibration model (e.g., ANTEX file) are given in the \"SITE/GPS_PHASE_CENTER\" block of data <ref group=\"footnotes\">See SINEX format at: http://www.iers.org/MainDisp.csl?pid=190-1100110. SINEX files can be found at ftp://cddis.gsfc.nasa.gov/pub/gps/products.</ref>.\n\n\nLet <math>{\\mathbf r}_{M}</math> be the position of Monument Marker in a ECEF reference frame. Let <math>{\\boldsymbol \\Delta}_{ARP}</math> be the offset vector defining the ARP position relative to the Monument Marker, and <math>{\\boldsymbol \\Delta}_{APC}</math> the offset vector defining the APC position relative to the ARP. Thence the receiver APC position <math>{\\mathbf r}</math>, in a ECEF reference frame is given by <ref group=\"footnotes\">Note: As commented before, <math>{\\boldsymbol \\Delta}_{APC}</math> is a frequency dependent correction. Equation \n\n::<math>\n{\\boldsymbol \\Delta}_{APC_{LC}}=\\frac{f_1^2 {\\boldsymbol \\Delta}_{APC_{L1}}-f_2^2 {\\boldsymbol \\Delta}_{APC_{L2}}}{f_1^2-f_2^2}</math>\n\n\n gives the correction <math>{\\boldsymbol \\Delta}_{{APC}_{LC}}</math> from the L1, L2 APCs vectors.</ref>:\n\n::<math>\n{\\mathbf r}={\\mathbf r}_M+{\\boldsymbol \\Delta}_{ARP}+{\\boldsymbol \\Delta}_{APC} \\qquad\\mbox{(1)}</math>\n\n\n::{|\n|+align=\"bottom\"|''Figure 2: Receiver Antenna Phase Centre: Range and position domain effect.''\n| [[File:Rx_APC_Ex2c2.png|none|thumb|400px|frameless]]\n| [[File: Rx_APC_Ex2c3.png |none|thumb|400px|frameless]]\n|-\n| [[File: Rx_APC_Ex2c1.png|none|thumb|400px|frameless]]\n| '' First row shows the horizontal (left) and vertical (right) positioning error using (blue) or not using (red) the Receiver APC correction. The variation in range is shown in the second row at left. As the APC vector is along the vertical axis, its effect is a displacement in the vertical component ''\n|}\n\n\nFigure 2, shows an example illustrating the effect of APC correction in the positioning domain (first row) and range domain (second row). The solution computed using the APC correction is shown in blue and the solution without using the APC in red. The projection in range of the APC offset is shown in the second row at left. The results correspond to an Ashtech-ZXII3 receiver with ASH70093D_M antenna, located at coordinates <math>\\lambda=34^o45^m</math>, <math>\\phi=30^o36^m</math> (Israel), on May 2nd 2000 and positioned in [[Code and Carrier Based Positioning (PPP)|Kinematic Precise Point Positioning (PPP)]] mode.\n\n\n\n==Notes==\n<references group=\"footnotes\"/>\n\n\n[[Category:Fundamentals]]\n[[Category:GNSS Measurements Modelling]]"
                    }
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