[{"data":1,"prerenderedAt":1725},["ShallowReactive",2],{"blog-\u002Fblog\u002Frtk-gps-real-time-kinematic":3,"blog-surround-\u002Fblog\u002Frtk-gps-real-time-kinematic":1714},{"id":4,"title":5,"author":6,"body":7,"category":1681,"description":1682,"extension":1683,"image":1684,"meta":1685,"navigation":1706,"path":1707,"publishedAt":1708,"readTime":1709,"seo":1710,"sitemap":1711,"stem":1712,"__hash__":1713},"blog\u002Fblog\u002F21.rtk-gps-real-time-kinematic.md","Real-Time Kinematic (RTK): Instantaneous Precision in GPS Surveying","Surveyiiing Expert",{"type":8,"value":9,"toc":1657},"minimark",[10,15,32,36,49,53,69,73,90,94,903,1059,1063,1112,1116,1177,1263,1267,1479,1483,1553,1557,1574,1578,1638,1642,1645,1649],[11,12,14],"h2",{"id":13},"overview","Overview",[16,17,18,22,23,27,28,31],"p",{},[19,20,21],"strong",{},"Real-Time Kinematic (RTK)"," surveying is the pinnacle of satellite-based positioning for the site engineer. Unlike traditional GPS methods that require post-processing of data in an office, RTK provides relative positions instantaneously as the roving receiver occupies a point ",[24,25,26],"span",{},"1",". By using a dedicated data link between a fixed base station and a mobile rover, the system resolves integer ambiguities \"on-the-fly,\" delivering centimetre-level accuracy in seconds ",[24,29,30],{},"1, 2",".",[11,33,35],{"id":34},"why-this-matters","Why This Matters",[16,37,38,39,42,43,46,47,31],{},"For the engineering surveyor, time is the most expensive variable. RTK eliminates the \"wait and see\" risk of post-processing. It allows for the immediate ",[19,40,41],{},"setting-out"," of design coordinates and the rapid capture of topographic detail ",[24,44,45],{},"3",". If a point is blocked or a measurement is suspect, the surveyor knows immediately, rather than discovering the error hours later at a desk ",[24,48,26],{},[11,50,52],{"id":51},"background","Background",[16,54,55,56,59,60,63,64,66,67,31],{},"The major hurdle in high-precision GPS is the time required for a significant change in satellite-receiver geometry to resolve the ",[19,57,58],{},"initial integer ambiguities"," ",[24,61,62],{},"2",". RTK overcomes this by utilizing a base station at a known position to transmit both code and carrier phase data to the rover ",[24,65,45],{},". This allows the rover's on-board processor to solve for coordinate differences relative to the base in real-time ",[24,68,26],{},[11,70,72],{"id":71},"theory","Theory",[16,74,75,76,79,80,83,84,87,88,31],{},"RTK relies on ",[19,77,78],{},"Differential GPS (DGPS)"," principles, where errors common to both receivers (such as satellite clock bias, orbital errors, and atmospheric refraction) are cancelled out over short baselines ",[24,81,82],{},"4, 5",". The \"Real-Time\" component is achieved via ",[19,85,86],{},"mobile data communication"," (usually radio modems or GSM), which must have sufficient bandwidth to transmit complex carrier phase data every epoch ",[24,89,26],{},[11,91,93],{"id":92},"mathematical-principles","Mathematical Principles",[16,95,96,97,100,101,59,900],{},"The core of RTK is the ",[19,98,99],{},"Double Difference"," algorithm, which eliminates receiver and satellite clock offsets.\nThe pure phase observation equation is:\n",[24,102,105,271],{"className":103},[104],"katex",[24,106,109],{"className":107},[108],"katex-mathml",[110,111,113],"math",{"xmlns":112},"http:\u002F\u002Fwww.w3.org\u002F1998\u002FMath\u002FMathML",[114,115,116,266],"semantics",{},[117,118,119,124,129,138,141,144,153,156,158,165,169,175,177,180,182,185,188,194,196,202,204,206,208,215,217,223,225,228,231,234,236,251,253],"mrow",{},[120,121,123],"mi",{"mathvariant":122},"normal","Φ",[125,126,128],"mo",{"stretchy":127},"false","(",[130,131,132,135],"msub",{},[120,133,134],{},"t",[120,136,137],{},"r",[125,139,140],{"stretchy":127},")",[125,142,143],{},"=",[145,146,147,150],"mfrac",{},[120,148,149],{},"f",[120,151,152],{},"c",[120,154,155],{},"R",[125,157,128],{"stretchy":127},[130,159,160,162],{},[120,161,134],{},[120,163,164],{},"s",[125,166,168],{"separator":167},"true",",",[130,170,171,173],{},[120,172,134],{},[120,174,137],{},[125,176,140],{"stretchy":127},[125,178,179],{},"−",[120,181,149],{},[125,183,184],{"stretchy":127},"[",[120,186,187],{},"δ",[130,189,190,192],{},[120,191,134],{},[120,193,137],{},[125,195,128],{"stretchy":127},[130,197,198,200],{},[120,199,134],{},[120,201,137],{},[125,203,140],{"stretchy":127},[125,205,179],{},[120,207,187],{},[209,210,211,213],"msup",{},[120,212,134],{},[120,214,164],{},[125,216,128],{"stretchy":127},[209,218,219,221],{},[120,220,134],{},[120,222,164],{},[125,224,140],{"stretchy":127},[125,226,227],{"stretchy":127},"]",[125,229,230],{},"+",[120,232,233],{},"N",[125,235,230],{},[130,237,238,241],{},[120,239,240],{},"e",[117,242,243,246,249],{},[120,244,245],{},"I",[120,247,248],{},"O",[120,250,233],{},[125,252,230],{},[130,254,255,257],{},[120,256,240],{},[117,258,259,262,264],{},[120,260,261],{},"T",[120,263,155],{},[120,265,248],{},[267,268,270],"annotation",{"encoding":269},"application\u002Fx-tex","\\Phi(t_r) = \\frac{f}{c} R(t_s, t_r) - f[\\delta t_r(t_r) - \\delta t^s(t^s)] + N + e_{ION} + e_{TRO}",[24,272,275,366,560,671,756,776,843],{"className":273,"ariaHidden":167},[274],"katex-html",[24,276,279,284,288,292,350,354,359,363],{"className":277},[278],"base",[24,280],{"className":281,"style":283},[282],"strut","height:1em;vertical-align:-0.25em;",[24,285,123],{"className":286},[287],"mord",[24,289,128],{"className":290},[291],"mopen",[24,293,295,299],{"className":294},[287],[24,296,134],{"className":297},[287,298],"mathnormal",[24,300,303],{"className":301},[302],"msupsub",[24,304,308,341],{"className":305},[306,307],"vlist-t","vlist-t2",[24,309,312,336],{"className":310},[311],"vlist-r",[24,313,317],{"className":314,"style":316},[315],"vlist","height:0.1514em;",[24,318,320,325],{"style":319},"top:-2.55em;margin-left:0em;margin-right:0.05em;",[24,321],{"className":322,"style":324},[323],"pstrut","height:2.7em;",[24,326,332],{"className":327},[328,329,330,331],"sizing","reset-size6","size3","mtight",[24,333,137],{"className":334,"style":335},[287,298,331],"margin-right:0.0278em;",[24,337,340],{"className":338},[339],"vlist-s","​",[24,342,344],{"className":343},[311],[24,345,348],{"className":346,"style":347},[315],"height:0.15em;",[24,349],{},[24,351,140],{"className":352},[353],"mclose",[24,355],{"className":356,"style":358},[357],"mspace","margin-right:0.2778em;",[24,360,143],{"className":361},[362],"mrel",[24,364],{"className":365,"style":358},[357],[24,367,369,373,451,455,458,498,502,506,546,549,553,557],{"className":368},[278],[24,370],{"className":371,"style":372},[282],"height:1.2772em;vertical-align:-0.345em;",[24,374,376,380,448],{"className":375},[287],[24,377],{"className":378},[291,379],"nulldelimiter",[24,381,383],{"className":382},[145],[24,384,386,439],{"className":385},[306,307],[24,387,389,436],{"className":388},[311],[24,390,393,409,420],{"className":391,"style":392},[315],"height:0.9322em;",[24,394,396,400],{"style":395},"top:-2.655em;",[24,397],{"className":398,"style":399},[323],"height:3em;",[24,401,403],{"className":402},[328,329,330,331],[24,404,406],{"className":405},[287,331],[24,407,152],{"className":408},[287,298,331],[24,410,412,415],{"style":411},"top:-3.23em;",[24,413],{"className":414,"style":399},[323],[24,416],{"className":417,"style":419},[418],"frac-line","border-bottom-width:0.04em;",[24,421,423,426],{"style":422},"top:-3.4461em;",[24,424],{"className":425,"style":399},[323],[24,427,429],{"className":428},[328,329,330,331],[24,430,432],{"className":431},[287,331],[24,433,149],{"className":434,"style":435},[287,298,331],"margin-right:0.1076em;",[24,437,340],{"className":438},[339],[24,440,442],{"className":441},[311],[24,443,446],{"className":444,"style":445},[315],"height:0.345em;",[24,447],{},[24,449],{"className":450},[353,379],[24,452,155],{"className":453,"style":454},[287,298],"margin-right:0.0077em;",[24,456,128],{"className":457},[291],[24,459,461,464],{"className":460},[287],[24,462,134],{"className":463},[287,298],[24,465,467],{"className":466},[302],[24,468,470,490],{"className":469},[306,307],[24,471,473,487],{"className":472},[311],[24,474,476],{"className":475,"style":316},[315],[24,477,478,481],{"style":319},[24,479],{"className":480,"style":324},[323],[24,482,484],{"className":483},[328,329,330,331],[24,485,164],{"className":486},[287,298,331],[24,488,340],{"className":489},[339],[24,491,493],{"className":492},[311],[24,494,496],{"className":495,"style":347},[315],[24,497],{},[24,499,168],{"className":500},[501],"mpunct",[24,503],{"className":504,"style":505},[357],"margin-right:0.1667em;",[24,507,509,512],{"className":508},[287],[24,510,134],{"className":511},[287,298],[24,513,515],{"className":514},[302],[24,516,518,538],{"className":517},[306,307],[24,519,521,535],{"className":520},[311],[24,522,524],{"className":523,"style":316},[315],[24,525,526,529],{"style":319},[24,527],{"className":528,"style":324},[323],[24,530,532],{"className":531},[328,329,330,331],[24,533,137],{"className":534,"style":335},[287,298,331],[24,536,340],{"className":537},[339],[24,539,541],{"className":540},[311],[24,542,544],{"className":543,"style":347},[315],[24,545],{},[24,547,140],{"className":548},[353],[24,550],{"className":551,"style":552},[357],"margin-right:0.2222em;",[24,554,179],{"className":555},[556],"mbin",[24,558],{"className":559,"style":552},[357],[24,561,563,566,569,572,576,616,619,659,662,665,668],{"className":562},[278],[24,564],{"className":565,"style":283},[282],[24,567,149],{"className":568,"style":435},[287,298],[24,570,184],{"className":571},[291],[24,573,187],{"className":574,"style":575},[287,298],"margin-right:0.0379em;",[24,577,579,582],{"className":578},[287],[24,580,134],{"className":581},[287,298],[24,583,585],{"className":584},[302],[24,586,588,608],{"className":587},[306,307],[24,589,591,605],{"className":590},[311],[24,592,594],{"className":593,"style":316},[315],[24,595,596,599],{"style":319},[24,597],{"className":598,"style":324},[323],[24,600,602],{"className":601},[328,329,330,331],[24,603,137],{"className":604,"style":335},[287,298,331],[24,606,340],{"className":607},[339],[24,609,611],{"className":610},[311],[24,612,614],{"className":613,"style":347},[315],[24,615],{},[24,617,128],{"className":618},[291],[24,620,622,625],{"className":621},[287],[24,623,134],{"className":624},[287,298],[24,626,628],{"className":627},[302],[24,629,631,651],{"className":630},[306,307],[24,632,634,648],{"className":633},[311],[24,635,637],{"className":636,"style":316},[315],[24,638,639,642],{"style":319},[24,640],{"className":641,"style":324},[323],[24,643,645],{"className":644},[328,329,330,331],[24,646,137],{"className":647,"style":335},[287,298,331],[24,649,340],{"className":650},[339],[24,652,654],{"className":653},[311],[24,655,657],{"className":656,"style":347},[315],[24,658],{},[24,660,140],{"className":661},[353],[24,663],{"className":664,"style":552},[357],[24,666,179],{"className":667},[556],[24,669],{"className":670,"style":552},[357],[24,672,674,677,680,711,714,743,747,750,753],{"className":673},[278],[24,675],{"className":676,"style":283},[282],[24,678,187],{"className":679,"style":575},[287,298],[24,681,683,686],{"className":682},[287],[24,684,134],{"className":685},[287,298],[24,687,689],{"className":688},[302],[24,690,692],{"className":691},[306],[24,693,695],{"className":694},[311],[24,696,699],{"className":697,"style":698},[315],"height:0.6644em;",[24,700,702,705],{"style":701},"top:-3.063em;margin-right:0.05em;",[24,703],{"className":704,"style":324},[323],[24,706,708],{"className":707},[328,329,330,331],[24,709,164],{"className":710},[287,298,331],[24,712,128],{"className":713},[291],[24,715,717,720],{"className":716},[287],[24,718,134],{"className":719},[287,298],[24,721,723],{"className":722},[302],[24,724,726],{"className":725},[306],[24,727,729],{"className":728},[311],[24,730,732],{"className":731,"style":698},[315],[24,733,734,737],{"style":701},[24,735],{"className":736,"style":324},[323],[24,738,740],{"className":739},[328,329,330,331],[24,741,164],{"className":742},[287,298,331],[24,744,746],{"className":745},[353],")]",[24,748],{"className":749,"style":552},[357],[24,751,230],{"className":752},[556],[24,754],{"className":755,"style":552},[357],[24,757,759,763,767,770,773],{"className":758},[278],[24,760],{"className":761,"style":762},[282],"height:0.7667em;vertical-align:-0.0833em;",[24,764,233],{"className":765,"style":766},[287,298],"margin-right:0.109em;",[24,768],{"className":769,"style":552},[357],[24,771,230],{"className":772},[556],[24,774],{"className":775,"style":552},[357],[24,777,779,783,834,837,840],{"className":778},[278],[24,780],{"className":781,"style":782},[282],"height:0.7333em;vertical-align:-0.15em;",[24,784,786,789],{"className":785},[287],[24,787,240],{"className":788},[287,298],[24,790,792],{"className":791},[302],[24,793,795,826],{"className":794},[306,307],[24,796,798,823],{"className":797},[311],[24,799,802],{"className":800,"style":801},[315],"height:0.3283em;",[24,803,804,807],{"style":319},[24,805],{"className":806,"style":324},[323],[24,808,810],{"className":809},[328,329,330,331],[24,811,813,817,820],{"className":812},[287,331],[24,814,245],{"className":815,"style":816},[287,298,331],"margin-right:0.0785em;",[24,818,248],{"className":819,"style":335},[287,298,331],[24,821,233],{"className":822,"style":766},[287,298,331],[24,824,340],{"className":825},[339],[24,827,829],{"className":828},[311],[24,830,832],{"className":831,"style":347},[315],[24,833],{},[24,835],{"className":836,"style":552},[357],[24,838,230],{"className":839},[556],[24,841],{"className":842,"style":552},[357],[24,844,846,850],{"className":845},[278],[24,847],{"className":848,"style":849},[282],"height:0.5806em;vertical-align:-0.15em;",[24,851,853,856],{"className":852},[287],[24,854,240],{"className":855},[287,298],[24,857,859],{"className":858},[302],[24,860,862,892],{"className":861},[306,307],[24,863,865,889],{"className":864},[311],[24,866,868],{"className":867,"style":801},[315],[24,869,870,873],{"style":319},[24,871],{"className":872,"style":324},[323],[24,874,876],{"className":875},[328,329,330,331],[24,877,879,883,886],{"className":878},[287,331],[24,880,261],{"className":881,"style":882},[287,298,331],"margin-right:0.1389em;",[24,884,155],{"className":885,"style":454},[287,298,331],[24,887,248],{"className":888,"style":335},[287,298,331],[24,890,340],{"className":891},[339],[24,893,895],{"className":894},[311],[24,896,898],{"className":897,"style":347},[315],[24,899],{},[24,901,902],{},"6",[16,904,905,906,936,937,967,968,936,998,1026,1027,1055,1056,31],{},"By differencing observations between two receivers (",[24,907,909,923],{"className":908},[104],[24,910,912],{"className":911},[108],[110,913,914],{"xmlns":112},[114,915,916,921],{},[117,917,918],{},[120,919,920],{},"A",[267,922,920],{"encoding":269},[24,924,926],{"className":925,"ariaHidden":167},[274],[24,927,929,933],{"className":928},[278],[24,930],{"className":931,"style":932},[282],"height:0.6833em;",[24,934,920],{"className":935},[287,298]," and ",[24,938,940,954],{"className":939},[104],[24,941,943],{"className":942},[108],[110,944,945],{"xmlns":112},[114,946,947,952],{},[117,948,949],{},[120,950,951],{},"B",[267,953,951],{"encoding":269},[24,955,957],{"className":956,"ariaHidden":167},[274],[24,958,960,963],{"className":959},[278],[24,961],{"className":962,"style":932},[282],[24,964,951],{"className":965,"style":966},[287,298],"margin-right:0.0502em;",") and two satellites (",[24,969,971,985],{"className":970},[104],[24,972,974],{"className":973},[108],[110,975,976],{"xmlns":112},[114,977,978,983],{},[117,979,980],{},[981,982,26],"mn",{},[267,984,26],{"encoding":269},[24,986,988],{"className":987,"ariaHidden":167},[274],[24,989,991,995],{"className":990},[278],[24,992],{"className":993,"style":994},[282],"height:0.6444em;",[24,996,26],{"className":997},[287],[24,999,1001,1014],{"className":1000},[104],[24,1002,1004],{"className":1003},[108],[110,1005,1006],{"xmlns":112},[114,1007,1008,1012],{},[117,1009,1010],{},[981,1011,62],{},[267,1013,62],{"encoding":269},[24,1015,1017],{"className":1016,"ariaHidden":167},[274],[24,1018,1020,1023],{"className":1019},[278],[24,1021],{"className":1022,"style":994},[282],[24,1024,62],{"className":1025},[287],"), the resultant equation removes the clock errors and leaves the baseline vector as the primary unknown, provided the integer ambiguity (",[24,1028,1030,1043],{"className":1029},[104],[24,1031,1033],{"className":1032},[108],[110,1034,1035],{"xmlns":112},[114,1036,1037,1041],{},[117,1038,1039],{},[120,1040,233],{},[267,1042,233],{"encoding":269},[24,1044,1046],{"className":1045,"ariaHidden":167},[274],[24,1047,1049,1052],{"className":1048},[278],[24,1050],{"className":1051,"style":932},[282],[24,1053,233],{"className":1054,"style":766},[287,298],") can be resolved ",[24,1057,1058],{},"4, 7",[11,1060,1062],{"id":1061},"field-workflow","Field Workflow",[1064,1065,1066,1071,1076,1080,1085,1089,1094,1098,1103,1107],"steps",{},[1067,1068,1070],"h3",{"id":1069},"base-station-setup","Base Station Setup",[16,1072,1073,1074,31],{},"Set up a high-quality dual-frequency receiver over a point with known coordinates. Connect the transmitter (radio modem) and ensure a clear line of sight for the antenna ",[24,1075,45],{},[1067,1077,1079],{"id":1078},"rover-initialization","Rover Initialization",[16,1081,1082,1083,31],{},"Power on the roving receiver. It must \"lock on\" to a minimum of five satellites to begin ambiguity resolution. The data link must be stable to receive the base station's corrections ",[24,1084,45],{},[1067,1086,1088],{"id":1087},"ambiguity-resolution-initialization","Ambiguity Resolution (Initialization)",[16,1090,1091,1092,31],{},"Wait for the system to achieve a \"Fixed\" solution. Modern \"On-the-Fly\" (OTF) systems can resolve these ambiguities while the rover is moving ",[24,1093,62],{},[1067,1095,1097],{"id":1096},"capture-or-set-out","Capture or Set-Out",[16,1099,1100,1101,31],{},"Once \"Fixed,\" the rover can capture topographic points or use graphical on-board software to guide the surveyor to design coordinates ",[24,1102,45],{},[1067,1104,1106],{"id":1105},"verification","Verification",[16,1108,1109,1110,31],{},"Periodically check the RTK solution by occupying a different known control point to ensure the ambiguity resolution remains correct ",[24,1111,45],{},[11,1113,1115],{"id":1114},"step-by-step-example-setting-out","Step-by-Step Example: Setting Out",[16,1117,1118,1121,1122,1176],{},[19,1119,1120],{},"Scenario:"," Set out a building corner with design coordinates ",[24,1123,1125,1148],{"className":1124},[104],[24,1126,1128],{"className":1127},[108],[110,1129,1130],{"xmlns":112},[114,1131,1132,1145],{},[117,1133,1134,1136,1139,1141,1143],{},[125,1135,128],{"stretchy":127},[120,1137,1138],{},"E",[125,1140,168],{"separator":167},[120,1142,233],{},[125,1144,140],{"stretchy":127},[267,1146,1147],{"encoding":269},"(E, N)",[24,1149,1151],{"className":1150,"ariaHidden":167},[274],[24,1152,1154,1157,1160,1164,1167,1170,1173],{"className":1153},[278],[24,1155],{"className":1156,"style":283},[282],[24,1158,128],{"className":1159},[291],[24,1161,1138],{"className":1162,"style":1163},[287,298],"margin-right:0.0576em;",[24,1165,168],{"className":1166},[501],[24,1168],{"className":1169,"style":505},[357],[24,1171,233],{"className":1172,"style":766},[287,298],[24,1174,140],{"className":1175},[353]," using RTK.",[1178,1179,1180,1241,1249,1255],"ol",{},[1181,1182,1183,1186,1187,1238,1239,31],"li",{},[19,1184,1185],{},"Input Coordinates:"," Key the design ",[24,1188,1190,1211],{"className":1189},[104],[24,1191,1193],{"className":1192},[108],[110,1194,1195],{"xmlns":112},[114,1196,1197,1209],{},[117,1198,1199,1201,1203,1205,1207],{},[125,1200,128],{"stretchy":127},[120,1202,1138],{},[125,1204,168],{"separator":167},[120,1206,233],{},[125,1208,140],{"stretchy":127},[267,1210,1147],{"encoding":269},[24,1212,1214],{"className":1213,"ariaHidden":167},[274],[24,1215,1217,1220,1223,1226,1229,1232,1235],{"className":1216},[278],[24,1218],{"className":1219,"style":283},[282],[24,1221,128],{"className":1222},[291],[24,1224,1138],{"className":1225,"style":1163},[287,298],[24,1227,168],{"className":1228},[501],[24,1230],{"className":1231,"style":505},[357],[24,1233,233],{"className":1234,"style":766},[287,298],[24,1236,140],{"className":1237},[353]," into the palm-sized processor ",[24,1240,45],{},[1181,1242,1243,1246,1247,31],{},[19,1244,1245],{},"Navigate:"," The graphical output shows the surveyor's current position as a cross and the target as a dot ",[24,1248,45],{},[1181,1250,1251,1254],{},[19,1252,1253],{},"Refine:"," Move the pole-antenna in the direction indicated by the software's arrows.",[1181,1256,1257,1260,1261,31],{},[19,1258,1259],{},"Finalize:"," When the cross and dot coincide, the pole is at the exact setting-out position. Record the \"as-built\" position for a quality check ",[24,1262,45],{},[11,1264,1266],{"id":1265},"formula-breakdown","Formula Breakdown",[16,1268,1269,1272,1273,1384,1385,1424,1425,59,1468,1471,1472,1475,1476,31],{},[19,1270,1271],{},"Accuracy of RTK:","\nThe system typically achieves a precision of:\n",[24,1274,1276,1313],{"className":1275},[104],[24,1277,1279],{"className":1278},[108],[110,1280,1281],{"xmlns":112},[114,1282,1283,1310],{},[117,1284,1285,1288,1290,1293,1297,1299,1301,1303,1305,1308],{},[125,1286,1287],{},"±",[125,1289,128],{"stretchy":127},[981,1291,1292],{},"10",[1294,1295,1296],"mtext",{}," mm",[125,1298,230],{},[981,1300,26],{},[125,1302,179],{},[981,1304,62],{},[1294,1306,1307],{}," ppm",[125,1309,140],{"stretchy":127},[267,1311,1312],{"encoding":269},"\\pm (10 \\text{ mm} + 1-2 \\text{ ppm})",[24,1314,1316,1347,1366],{"className":1315,"ariaHidden":167},[274],[24,1317,1319,1322,1325,1328,1331,1338,1341,1344],{"className":1318},[278],[24,1320],{"className":1321,"style":283},[282],[24,1323,1287],{"className":1324},[287],[24,1326,128],{"className":1327},[291],[24,1329,1292],{"className":1330},[287],[24,1332,1335],{"className":1333},[287,1334],"text",[24,1336,1296],{"className":1337},[287],[24,1339],{"className":1340,"style":552},[357],[24,1342,230],{"className":1343},[556],[24,1345],{"className":1346,"style":552},[357],[24,1348,1350,1354,1357,1360,1363],{"className":1349},[278],[24,1351],{"className":1352,"style":1353},[282],"height:0.7278em;vertical-align:-0.0833em;",[24,1355,26],{"className":1356},[287],[24,1358],{"className":1359,"style":552},[357],[24,1361,179],{"className":1362},[556],[24,1364],{"className":1365,"style":552},[357],[24,1367,1369,1372,1375,1381],{"className":1368},[278],[24,1370],{"className":1371,"style":283},[282],[24,1373,62],{"className":1374},[287],[24,1376,1378],{"className":1377},[287,1334],[24,1379,1307],{"className":1380},[287],[24,1382,140],{"className":1383},[353],"\nThis means for a ",[24,1386,1388,1405],{"className":1387},[104],[24,1389,1391],{"className":1390},[108],[110,1392,1393],{"xmlns":112},[114,1394,1395,1402],{},[117,1396,1397,1399],{},[981,1398,26],{},[1294,1400,1401],{}," km",[267,1403,1404],{"encoding":269},"1 \\text{ km}",[24,1406,1408],{"className":1407,"ariaHidden":167},[274],[24,1409,1411,1415,1418],{"className":1410},[278],[24,1412],{"className":1413,"style":1414},[282],"height:0.6944em;",[24,1416,26],{"className":1417},[287],[24,1419,1421],{"className":1420},[287,1334],[24,1422,1401],{"className":1423},[287]," baseline, the expected error is approximately ",[24,1426,1428,1447],{"className":1427},[104],[24,1429,1431],{"className":1430},[108],[110,1432,1433],{"xmlns":112},[114,1434,1435,1444],{},[117,1436,1437,1439,1442],{},[125,1438,1287],{},[981,1440,1441],{},"12",[1294,1443,1296],{},[267,1445,1446],{"encoding":269},"\\pm 12 \\text{ mm}",[24,1448,1450],{"className":1449,"ariaHidden":167},[274],[24,1451,1453,1456,1459,1462],{"className":1452},[278],[24,1454],{"className":1455,"style":1353},[282],[24,1457,1287],{"className":1458},[287],[24,1460,1441],{"className":1461},[287],[24,1463,1465],{"className":1464},[287,1334],[24,1466,1296],{"className":1467},[287],[24,1469,1470],{},"8",". Note that this is relative to the ",[19,1473,1474],{},"Base Station",", so any error in the base station's coordinates will shift the entire site survey ",[24,1477,1478],{},"9",[11,1480,1482],{"id":1481},"practical-tips","Practical Tips",[1484,1485,1486,1494,1541],"ul",{},[1181,1487,1488,1491,1492,31],{},[19,1489,1490],{},"Loss of Lock:"," If you go under a tree or near a tall building, you may lose the \"Fixed\" status. You must remain static for a short time or return to an open area to regain the integer resolution ",[24,1493,45],{},[1181,1495,1496,1499,1500,1538,1539,31],{},[19,1497,1498],{},"Radio Range:"," The communication link is the \"weakest link.\" Use high-gain antennas if working over ",[24,1501,1503,1520],{"className":1502},[104],[24,1504,1506],{"className":1505},[108],[110,1507,1508],{"xmlns":112},[114,1509,1510,1517],{},[117,1511,1512,1515],{},[981,1513,1514],{},"5",[1294,1516,1401],{},[267,1518,1519],{"encoding":269},"5 \\text{ km}",[24,1521,1523],{"className":1522,"ariaHidden":167},[274],[24,1524,1526,1529,1532],{"className":1525},[278],[24,1527],{"className":1528,"style":1414},[282],[24,1530,1514],{"className":1531},[287],[24,1533,1535],{"className":1534},[287,1334],[24,1536,1401],{"className":1537},[287]," or in undulating terrain ",[24,1540,26],{},[1181,1542,1543,1546,1547,1550,1551,31],{},[19,1544,1545],{},"GDOP Awareness:"," Avoid working when the ",[19,1548,1549],{},"Geometric Dilution of Precision (GDOP)"," is high (e.g., satellites in a straight line), as this degrades the 3D intersection accuracy ",[24,1552,1292],{},[11,1554,1556],{"id":1555},"common-mistakes","Common Mistakes",[1484,1558,1559,1565],{},[1181,1560,1561,1564],{},[19,1562,1563],{},"Ignoring Base Stability:"," If the base tripod is bumped or settles into soft ground, all subsequent RTK points will be wrong. Always sandbag the base tripod.",[1181,1566,1567,1570,1571,31],{},[19,1568,1569],{},"Mixing Datums:"," Ensure the base station is using the same local transformation parameters as the design plan (e.g., WGS84 to National Grid) ",[24,1572,1573],{},"11",[11,1575,1577],{"id":1576},"faq","FAQ",[1579,1580,1581,1590,1632],"accordion",{},[1582,1583,1585],"accordion-item",{"label":1584},"What is the difference between 'Fixed' and 'Float'?",[16,1586,1587,1588,31],{},"A \"Fixed\" solution means the integer ambiguities have been resolved to whole numbers, providing centimetre accuracy. A \"Float\" solution means the ambiguities are still being estimated as decimals, resulting in decimetre or metre-level error ",[24,1589,1514],{},[1582,1591,1593],{"label":1592},"Can I use RTK for vertical control?",[16,1594,1595,1596,1599,1600,1628,1629,31],{},"Yes, but GPS heights are ",[19,1597,1598],{},"ellipsoidal",". You must apply a geoid-ellipsoid separation (",[24,1601,1603,1616],{"className":1602},[104],[24,1604,1606],{"className":1605},[108],[110,1607,1608],{"xmlns":112},[114,1609,1610,1614],{},[117,1611,1612],{},[120,1613,233],{},[267,1615,233],{"encoding":269},[24,1617,1619],{"className":1618,"ariaHidden":167},[274],[24,1620,1622,1625],{"className":1621},[278],[24,1623],{"className":1624,"style":932},[282],[24,1626,233],{"className":1627,"style":766},[287,298],") model to get orthometric heights (elevations) suitable for drainage ",[24,1630,1631],{},"12, 13",[1582,1633,1635],{"label":1634},"Does RTK work in tunnels?",[16,1636,1637],{},"No. GPS signals require a clear line of sight to the satellites. For underground work, use Weisbach Triangles or Gyro-theodolites .",[11,1639,1641],{"id":1640},"conclusion","Conclusion",[16,1643,1644],{},"RTK GPS has revolutionized site surveying by providing instantaneous, high-precision results. By mastering the data link and understanding the constraints of ambiguity resolution, the engineering surveyor can perform complex setting-out tasks with unprecedented speed and confidence.",[11,1646,1648],{"id":1647},"references","References",[16,1650,1651,1652,1656],{},"Schofield, W. (2001). ",[1653,1654,1655],"em",{},"Engineering Surveying",". 5th ed. Butterworth-Heinemann.",{"title":1658,"searchDepth":1659,"depth":1659,"links":1660},"",2,[1661,1662,1663,1664,1665,1666,1674,1675,1676,1677,1678,1679,1680],{"id":13,"depth":1659,"text":14},{"id":34,"depth":1659,"text":35},{"id":51,"depth":1659,"text":52},{"id":71,"depth":1659,"text":72},{"id":92,"depth":1659,"text":93},{"id":1061,"depth":1659,"text":1062,"children":1667},[1668,1670,1671,1672,1673],{"id":1069,"depth":1669,"text":1070},3,{"id":1078,"depth":1669,"text":1079},{"id":1087,"depth":1669,"text":1088},{"id":1096,"depth":1669,"text":1097},{"id":1105,"depth":1669,"text":1106},{"id":1114,"depth":1659,"text":1115},{"id":1265,"depth":1659,"text":1266},{"id":1481,"depth":1659,"text":1482},{"id":1555,"depth":1659,"text":1556},{"id":1576,"depth":1659,"text":1577},{"id":1640,"depth":1659,"text":1641},{"id":1647,"depth":1659,"text":1648},"Satellite Positioning","A technical guide to RTK GPS procedures, mobile data communication requirements, and real-time ambiguity resolution for engineering site work.","md","\u002Fimages\u002Frtk-gps.jpg",{"authorCredentials":1686,"authorBio":1687,"commentCount":1688,"tags":1689,"relatedTools":1694,"relatedArticles":1698,"sources":1701},"LS, P.Eng","Specialist in satellite positioning and real-time dimensional control.",0,[1690,1691,1681,1692,1693],"GPS","RTK","Setting Out","Real-Time",[1695,1696,1697],"GNSS Receiver","Radio Modem","Data Controller",[1699,1700],"wgs84-datum-projections","coordinate-transformations-helmert",[1702],{"title":1703,"type":1704,"note":1705},"Engineering Surveying (Fifth Edition)","Book","Primary source for RTK theory and site application.",true,"\u002Fblog\u002Frtk-gps-real-time-kinematic","2024-04-09",18,{"title":5,"description":1682},{"loc":1707},"blog\u002F21.rtk-gps-real-time-kinematic","nhE0qeuACn3gtZvCGpmtnP7wbMLEkoZSq79iQeAB_pc",[1715,1720],{"title":1716,"path":1717,"stem":1718,"description":1719,"children":-1},"Stadia Tacheometry: Mastering Optical Distance Measurement","\u002Fblog\u002Fstadia-tacheometry-optical-measurement","blog\u002F20.stadia-tacheometry-optical-measurement","A technical exploration of tacheometry theory and formulas for determining distances and elevations using a theodolite and stadia hair readings.",{"title":1721,"path":1722,"stem":1723,"description":1724,"children":-1},"WGS84 and Projections: The Mathematics of Global to Local Mapping","\u002Fblog\u002Fwgs84-datum-and-geodetic-projections","blog\u002F22.wgs84-datum-and-geodetic-projections","A deep dive into the WGS84 reference system, geodetic coordinates, and the formulas required to project a curved Earth onto a flat engineering site grid.",1783851945998]