[{"data":1,"prerenderedAt":1155},["ShallowReactive",2],{"knowledge-page-en-\u002Flearn\u002Frtk-baseline-length":3},{"article":4,"posts":337,"relatedPosts":338},{"id":5,"title":6,"author":7,"body":8,"category":322,"cover":323,"description":324,"extension":325,"meta":326,"navigation":327,"path":328,"publishedAt":329,"relatedArticles":330,"seo":333,"stem":334,"updatedAt":335,"__hash__":336},"knowledge_en\u002Fen\u002Flearn\u002Frtk-baseline-length.md","How far can you be from the base station?","Wilko",{"type":9,"value":10,"toc":312},"minimark",[11,16,20,23,44,48,159,163,166,182,190,194,197,200,220,224,227,253,257,264,267,306],[12,13,15],"h2",{"id":14},"what-is-baseline-length","What is baseline length?",[17,18,19],"p",{},"The baseline is the straight-line distance between your RTK rover and the reference station providing corrections. In a base-rover setup, that is your own base station. When using an NTRIP correction service, it is the nearest physical reference station in the network.",[17,21,22],{},"The shorter the baseline, the more similar the satellite signals seen by both rover and base — which means corrections are more accurate and Fix is faster. As the baseline grows, atmospheric differences (ionosphere and troposphere) between rover and base increase, making it harder for the receiver to resolve carrier phase ambiguities.",[24,25,27,32,36,40],"text-grid",{"additionalstyles":26},"mt-[60px]",[28,29],"text-grid-item",{"text":30,"title":31},"Fast Fix, centimetre accuracy","0–30 km",[28,33],{"text":34,"title":35},"Slower Fix — use VRS","30–60 km",[28,37],{"text":38,"title":39},"Fix becomes unreliable without VRS","60–100 km",[28,41],{"text":42,"title":43},"Use VRS or another network solution","100 km+",[12,45,47],{"id":46},"practical-limits-by-setup-type","Practical limits by setup type",[49,50,51,70],"table",{},[52,53,54],"thead",{},[55,56,57,61,64,67],"tr",{},[58,59,60],"th",{},"Setup type",[58,62,63],{},"Recommended max",[58,65,66],{},"Absolute max",[58,68,69],{},"Status",[71,72,73,92,109,126,143],"tbody",{},[55,74,75,83,86,89],{},[76,77,78,82],"td",{},[79,80,81],"strong",{},"Own base station"," — Single base, radio or NTRIP",[76,84,85],{},"10–15 km",[76,87,88],{},"~30 km",[76,90,91],{},"Best accuracy",[55,93,94,100,103,106],{},[76,95,96,99],{},[79,97,98],{},"NTRIP network, standard mountpoint"," — Nearest physical station",[76,101,102],{},"20–30 km",[76,104,105],{},"~50 km",[76,107,108],{},"Good in dense networks",[55,110,111,117,120,123],{},[76,112,113,116],{},[79,114,115],{},"NTRIP network, VRS mountpoint"," — Virtual reference station",[76,118,119],{},"Any distance in network",[76,121,122],{},"Network coverage area",[76,124,125],{},"Recommended for >30 km",[55,127,128,134,137,140],{},[76,129,130,133],{},[79,131,132],{},"NTRIP network, no VRS"," — Sparse station coverage",[76,135,136],{},"20 km",[76,138,139],{},"~40 km with degraded accuracy",[76,141,142],{},"Use VRS if available",[55,144,145,151,154,156],{},[76,146,147,150],{},[79,148,149],{},"PPP (Precise Point Positioning)"," — No local base needed",[76,152,153],{},"Global",[76,155,153],{},[76,157,158],{},"Minutes to converge, cm post-fix",[12,160,162],{"id":161},"what-happens-as-baseline-grows","What happens as baseline grows",[17,164,165],{},"Longer baselines introduce three problems that affect RTK performance:",[167,168,169,174,178],"cards",{"additionalstyles":26},[170,171],"cards-item",{"text":172,"title":173},"The ionosphere is a layer of charged particles that delays satellite signals. At short baselines, rover and base see nearly identical ionospheric conditions, so corrections cancel out the delay well. Beyond roughly 20–30 km, conditions diverge enough to degrade corrections, especially during high solar activity.","1. Ionospheric decorrelation",[170,175],{"text":176,"title":177},"The lower atmosphere also delays signals based on temperature, pressure and humidity. These vary across terrain. At longer baselines, especially with significant altitude differences between rover and base, tropospheric errors become significant.","2. Tropospheric decorrelation",[170,179],{"text":180,"title":181},"RTK Fix depends on resolving carrier phase ambiguities. At longer baselines, this calculation becomes harder and takes longer, or may not converge at all. The result is Float instead of Fix.","3. Slower ambiguity resolution",[183,184,187],"card",{"additionalstyles":26,"color":185,"title":186},"orange","Watch for this sign",[17,188,189],{},"If you are consistently stuck on Float and your environment is good (open sky, strong signal), long baseline is often the cause. Check the distance to the nearest reference station in your NTRIP sourcetable.",[12,191,193],{"id":192},"how-vrs-solves-long-baselines","How VRS solves long baselines",[17,195,196],{},"VRS (Virtual Reference Station) is a network feature where the NTRIP server computes a synthetic correction stream as if a real base station existed right next to your rover — typically within 1–2 km. It achieves this by interpolating data from multiple physical stations across the network.",[17,198,199],{},"To use VRS, your NTRIP client must send your position (a GGA sentence) to the server. The server uses that position to generate the virtual corrections and streams them back. If GGA is not sent, the VRS cannot generate a local correction and you will receive no data.",[201,202,204,210,215],"requirements",{"additionalstyles":26,"title":203},"VRS setup checklist",[205,206,207],"requirement-item",{},[17,208,209],{},"Enable GGA transmission in your NTRIP client.",[205,211,212],{},[17,213,214],{},"Select a mountpoint labelled VRS, MAC or RTCM3_VRS.",[205,216,217],{},[17,218,219],{},"Ensure you have a Single or Float solution first so GGA contains a valid position.",[12,221,223],{"id":222},"limits-by-device-type","Limits by device type",[17,225,226],{},"Different receivers handle long baselines differently depending on their processing engine and the signals they track.",[167,228,229,233,237,241,245,249],{"additionalstyles":26},[170,230],{"text":231,"title":232},"Multi-band. Use a VRS mountpoint beyond 30 km.","Emlid Reach RS2+ \u002F RS3 \u002F RS4 — ~60 km",[170,234],{"text":235,"title":236},"Pure network rover. VRS is strongly recommended.","Emlid Reach RX \u002F RX2 — ~30 km",[170,238],{"text":239,"title":240},"Advanced engines. VRS or MAC required beyond 30 km.","Trimble \u002F Leica — ~100 km",[170,242],{"text":243,"title":244},"Use an MSM5 mountpoint. Use VRS for longer baselines.","DJI RTK drones — ~30 km",[170,246],{"text":247,"title":248},"Entry-level multi-band receiver. Sensitive to baseline length.","u-blox ZED-F9P — ~20 km",[170,250],{"text":251,"title":252},"Short baselines only. No ionospheric correction.","Single-frequency receivers — ~10 km",[12,254,256],{"id":255},"tips-for-long-baseline-situations","Tips for long baseline situations",[183,258,261],{"additionalstyles":26,"color":259,"title":260},"green","Use VRS first",[17,262,263],{},"If your NTRIP service offers a VRS or MAC mountpoint, switch to it. This eliminates baseline as a factor entirely and is the single most effective change you can make.",[17,265,266],{},"If VRS is not available or you are using your own base station, these steps help:",[268,269,270,278,285,292,299],"stepper",{"additionalstyles":26},[271,272,275],"stepper-item",{"marker":273,"title":274},"1","Move your base closer",[17,276,277],{},"For own-base setups, the most direct solution is repositioning the base within 10–15 km of your work area.",[271,279,282],{"marker":280,"title":281},"2","Wait for better conditions",[17,283,284],{},"During high solar activity (solar maximum), ionospheric delays increase. Working early morning often gives better results.",[271,286,289],{"marker":287,"title":288},"3","Use a multi-band receiver",[17,290,291],{},"Dual or triple-frequency receivers can model and correct ionospheric delays using the difference between frequencies (L1\u002FL2\u002FL5). Single-frequency receivers cannot.",[271,293,296],{"marker":294,"title":295},"4","Increase initialisation time",[17,297,298],{},"At longer baselines, ambiguity resolution simply takes longer. Give the receiver 5–10 minutes in a stationary position before starting work.",[271,300,303],{"marker":301,"title":302},"5","Check elevation mask",[17,304,305],{},"A 15° elevation mask removes low-elevation satellites that carry the highest atmospheric errors at long baselines.",[183,307,309],{"additionalstyles":26,"color":185,"title":308},"Accuracy degrades with baseline even at Fix",[17,310,311],{},"RTK Fix does not guarantee centimetre accuracy at long baselines. At 50+ km without VRS, horizontal errors of 5–10 cm are common even with a Fix solution. For precision work, always verify with known control points.",{"title":313,"searchDepth":314,"depth":314,"links":315},"",2,[316,317,318,319,320,321],{"id":14,"depth":314,"text":15},{"id":46,"depth":314,"text":47},{"id":161,"depth":314,"text":162},{"id":192,"depth":314,"text":193},{"id":222,"depth":314,"text":223},{"id":255,"depth":314,"text":256},"learn","learn\u002Fhow-far-can-you-be-from-the-base-station.webp","Baseline length — the distance between your rover and the nearest reference station — directly affects whether you get RTK Fix, how fast you get it, and how accurate it is. Here is what every RTK user needs to know.","md",{},true,"\u002Fen\u002Flearn\u002Frtk-baseline-length","2026-07-25",[331,332],"\u002Fen\u002Flearn\u002Fwhat-is-vrs","\u002Fen\u002Flearn\u002Fwhat-is-gga",{"title":6,"description":324},"en\u002Flearn\u002Frtk-baseline-length",null,"yeaRAGNaezFD_GcEdCRK8Ash3gctEZjgZw5BfvONNWU",[],[339,744],{"id":340,"title":341,"author":342,"body":343,"category":322,"cover":735,"description":736,"extension":325,"meta":737,"navigation":327,"path":331,"publishedAt":329,"relatedArticles":738,"seo":741,"stem":742,"updatedAt":335,"__hash__":743},"knowledge_en\u002Fen\u002Flearn\u002Fwhat-is-vrs.md","What is VRS and when do you need it?","Yuri",{"type":9,"value":344,"toc":726},[345,349,356,359,362,380,384,387,419,426,430,433,508,512,538,542,549,552,558,565,569,572,644,648,651,720],[12,346,348],{"id":347},"what-vrs-is-and-why-it-exists","What VRS is and why it exists",[17,350,351,352,355],{},"VRS stands for ",[79,353,354],{},"Virtual Reference Station",". It is a network RTK technology that makes your receiver work as if a physical base station were located just beside you, wherever you are within the correction network's coverage area.",[17,357,358],{},"With a normal single-station NTRIP mountpoint, your rover receives corrections from one physical reference station. That station can be 20, 40 or even 60 kilometres away. As the baseline gets longer, the atmospheric conditions at your rover become less like those at the station. Ionospheric and tropospheric errors then make RTK initialisation slower and a Fixed solution less stable.",[17,360,361],{},"VRS solves that problem on the server. It combines observations from several surrounding reference stations, models the conditions at your location and sends a synthetic RTCM correction stream. To your receiver, it looks exactly like corrections from a nearby base station.",[24,363,364,368,372,376],{"additionalstyles":26},[28,365],{"text":366,"title":367},"Typical effective VRS baseline","1–2 km",[28,369],{"text":370,"title":371},"Reference stations used around you","3+",[28,373],{"text":374,"title":375},"Position message required by VRS","GGA",[28,377],{"text":378,"title":379},"Correction format your rover receives","RTCM3",[12,381,383],{"id":382},"how-vrs-works","How VRS works",[17,385,386],{},"VRS is a server-side calculation that runs invisibly behind your NTRIP connection. The sequence is straightforward:",[268,388,389,395,401,407,413],{"additionalstyles":26},[271,390,392],{"title":391},"Connect to a VRS mountpoint",[17,393,394],{},"Your NTRIP client connects to the correction service and sends an NMEA GGA sentence with its approximate position. This two-way communication is what makes VRS different from a normal single-station stream.",[271,396,398],{"title":397},"The server places you in the network",[17,399,400],{},"The VRS server uses your GGA position to identify the physical reference stations around you. It typically selects three or more nearby stations to build the correction model.",[271,402,404],{"title":403},"Atmospheric conditions are modelled",[17,405,406],{},"The server interpolates the ionospheric and tropospheric differences observed across those stations. It estimates the errors that apply at your exact working location.",[271,408,410],{"title":409},"A virtual station is created",[17,411,412],{},"The server synthesises an RTCM3 stream as if a base station existed only a kilometre or two from your rover. No physical hardware is installed at that virtual location.",[271,414,416],{"title":415},"Your receiver computes RTK normally",[17,417,418],{},"Your receiver processes the VRS corrections like any other RTCM3 stream. It does not need to know whether the corrections came from a real or virtual station; it simply benefits from the short effective baseline.",[183,420,423],{"additionalstyles":26,"color":421,"title":422},"primary","VRS changes the effective baseline, not your equipment",[17,424,425],{},"You still use the same rover, field software and NTRIP credentials. Select a VRS mountpoint and transmit GGA; the network does the additional calculation for you.",[12,427,429],{"id":428},"standard-mountpoint-vs-vrs","Standard mountpoint vs VRS",[17,431,432],{},"Both options use the same correction network. The important difference is how the correction stream is made.",[434,435,439,455,469,482,495],"compare-table",{"additionalstyles":26,"items":436,"label":437,"winner":438},"Standard mountpoint|VRS mountpoint","Standard NTRIP and VRS comparison","VRS mountpoint",[440,441,443,450],"compare-row",{"title":442},"Correction source",[444,445,447],"compare-cell",{"status":446},"positive",[17,448,449],{},"One physical reference station.",[444,451,452],{"status":446},[17,453,454],{},"A virtual station calculated from multiple physical stations.",[440,456,458,464],{"title":457},"Effective baseline",[444,459,461],{"status":460},"negative",[17,462,463],{},"The actual distance to the selected station. It may be tens of kilometres.",[444,465,466],{"status":446},[17,467,468],{},"Usually around 1–2 km, even when physical stations are far away.",[440,470,472,477],{"title":471},"GGA transmission",[444,473,474],{"status":446},[17,475,476],{},"Usually not required.",[444,478,479],{"status":460},[17,480,481],{},"Required so the server can generate corrections for your location.",[440,483,485,490],{"title":484},"Working over a large area",[444,486,487],{"status":460},[17,488,489],{},"You may need to change mountpoints as the nearest station changes.",[444,491,492],{"status":446},[17,493,494],{},"The network adapts to your position automatically.",[440,496,498,503],{"title":497},"Fix reliability at long distances",[444,499,500],{"status":460},[17,501,502],{},"Can degrade as atmospheric differences increase.",[444,504,505],{"status":446},[17,506,507],{},"Typically faster to initialise and more stable across the network.",[12,509,511],{"id":510},"when-to-use-vrs-and-when-not-to","When to use VRS — and when not to",[167,513,514,518,522,526,530,534],{"additionalstyles":26},[170,515],{"text":516,"title":517},"Once the nearest physical station is more than roughly 20–30 km away, a VRS stream reduces the baseline-related errors that can keep a receiver in Float or make Fix drop.","Use VRS beyond 20–30 km",[170,519],{"text":520,"title":521},"For work that covers a large area in one day, VRS follows your approximate location. You do not need to keep choosing a different physical station as you travel.","Use VRS when moving across a region",[170,523],{"text":524,"title":525},"If your sky view and connection are good but Fix repeatedly drops on a standard mountpoint, switching to VRS removes baseline length as a likely cause.","Use VRS for unstable Fix",[170,527],{"text":528,"title":529},"High solar activity and geomagnetic disturbances increase ionospheric errors. The network model in a VRS service can compensate for spatial differences much better than a distant single station.","Use VRS during disturbed conditions",[170,531],{"text":532,"title":533},"Within about 15 km of a physical reference station, the atmospheric difference is usually small. A standard mountpoint can work just as well and does not depend on GGA.","A nearby station may be enough",[170,535],{"text":536,"title":537},"The server must receive your GGA position. Without mobile data at the rover, use a local base and radio link or another correction method that works offline.","VRS needs an internet connection",[12,539,541],{"id":540},"the-gga-requirement-explained","The GGA requirement explained",[17,543,544,545,548],{},"VRS has one requirement that a standard NTRIP connection normally does not: your client must send an ",[79,546,547],{},"NMEA GGA sentence"," to the caster. GGA includes latitude, longitude, altitude and fix quality. The server uses it to decide which part of its atmospheric model applies to you and where to place the virtual reference station.",[17,550,551],{},"The position does not need to be centimetre accurate. A Single or Float position is enough to locate you in the correct network area. However, the GGA must contain a valid position before you connect.",[183,553,555],{"additionalstyles":26,"color":185,"title":554},"Connected, but receiving 0 bytes per second? Check GGA first.",[17,556,557],{},"When GGA is disabled, a connection to a VRS mountpoint can look successful but the caster may send no correction data. Your receiver stays on Single and there may be no obvious error message. Enable GGA transmission, then reconnect.",[183,559,562],{"additionalstyles":560,"color":421,"title":561},"mt-[30px]","Wait for a valid initial position",[17,563,564],{},"Before connecting, give the receiver 30–60 seconds outdoors to obtain satellite lock. A GGA sentence with zero coordinates can be rejected by the server or place the virtual station in the wrong area.",[12,566,568],{"id":567},"how-to-enable-vrs-on-your-device","How to enable VRS on your device",[17,570,571],{},"Select the VRS mountpoint supplied by your correction provider, then make sure GGA transmission is enabled. The wording differs slightly by application.",[573,574,576,591,601,614,624,634],"device-tabs",{"additionalstyles":26,"items":575},"Emlid Flow|Trimble Access|SW Maps|FieldGenius|DJI Pilot|Lefebure NTRIP",[577,578,580],"device-tab",{"name":579},"Emlid Flow",[17,581,582,583,586,587,590],{},"Go to ",[79,584,585],{},"Correction input → NTRIP",". Select your provider's VRS mountpoint, enable ",[79,588,589],{},"Send GGA to caster",", then connect after the receiver has a Single solution.",[577,592,594],{"name":593},"Trimble Access",[17,595,596,597,600],{},"Open ",[79,598,599],{},"Survey Style → Rover radio",", then enter the VRS mountpoint in the NTRIP settings. Trimble Access normally sends GGA automatically while NTRIP is active.",[577,602,604],{"name":603},"SW Maps",[17,605,582,606,609,610,613],{},[79,607,608],{},"Settings → NTRIP Client",", choose the VRS mountpoint from the sourcetable and enable ",[79,611,612],{},"Transmit GGA"," before tapping Connect.",[577,615,617],{"name":616},"FieldGenius",[17,618,619,620,623],{},"Choose ",[79,621,622],{},"Set Up Corrections → RTK via Internet",", add a source with the VRS mountpoint and enable GGA transmission in the data-link settings. Confirm the antenna height, then connect.",[577,625,627],{"name":626},"DJI Pilot",[17,628,629,630,633],{},"In ",[79,631,632],{},"RTK Settings → Custom Network RTK",", enter the VRS mountpoint provided by your service. DJI sends GGA automatically after it has GPS lock, so configure it outdoors.",[577,635,637],{"name":636},"Lefebure NTRIP",[17,638,639,640,643],{},"Enter the caster host, port and VRS mountpoint. Enable ",[79,641,642],{},"Send GGA"," in the app settings and select your receiver or the phone's internal GPS as the GGA source.",[12,645,647],{"id":646},"vrs-by-another-name","VRS by another name",[17,649,650],{},"VRS is the most common name for network RTK, but it is not the only approach. A sourcetable may also contain these alternatives:",[49,652,653,666],{},[52,654,655],{},[55,656,657,660,663],{},[58,658,659],{},"Name",[58,661,662],{},"What it does",[58,664,665],{},"What you need to know",[71,667,668,681,694,707],{},[55,669,670,675,678],{},[76,671,672],{},[79,673,674],{},"MAC",[76,676,677],{},"The caster sends observations from a master station and auxiliary stations; the receiver performs the network calculation.",[76,679,680],{},"Common with Leica systems. GGA is not always required.",[55,682,683,688,691],{},[76,684,685],{},[79,686,687],{},"FKP",[76,689,690],{},"The caster sends area-correction parameters that the receiver applies to a single-station stream.",[76,692,693],{},"An older network format that is less common today.",[55,695,696,701,704],{},[76,697,698],{},[79,699,700],{},"iMAX",[76,702,703],{},"A personalised version of the Master-Auxiliary approach.",[76,705,706],{},"Functionally similar to VRS for most users.",[55,708,709,714,717],{},[76,710,711],{},[79,712,713],{},"SSR \u002F SSRZ",[76,715,716],{},"Separately models satellite orbits, clocks and atmospheric effects.",[76,718,719],{},"A newer approach that is becoming more common in modern networks.",[183,721,723],{"additionalstyles":26,"color":259,"title":722},"For most users, choose the VRS mountpoint",[17,724,725],{},"Unless your receiver or correction provider specifically asks for MAC, FKP or another format, VRS is the practical default. It works with modern RTK receivers and gives you near-local network corrections throughout the covered area.",{"title":313,"searchDepth":314,"depth":314,"links":727},[728,729,730,731,732,733,734],{"id":347,"depth":314,"text":348},{"id":382,"depth":314,"text":383},{"id":428,"depth":314,"text":429},{"id":510,"depth":314,"text":511},{"id":540,"depth":314,"text":541},{"id":567,"depth":314,"text":568},{"id":646,"depth":314,"text":647},"learn\u002Fwhat-is-vrs.webp","VRS (Virtual Reference Station) makes a correction network behave as though a base station is right beside your rover. It eliminates long-baseline errors, improves Fix reliability across a network and is simple to use once GGA transmission is enabled.",{},[739,740],"\u002Fen\u002Flearn\u002Fwhat-is-ntrip","\u002Fen\u002Flearn\u002Ffloat-vs-fix",{"title":341,"description":736},"en\u002Flearn\u002Fwhat-is-vrs","Q_R7dGN8SakA5nbtnxs_dK8uAMrv0Wf41kDVzWa369Y",{"id":745,"title":746,"author":342,"body":747,"category":322,"cover":1148,"description":1149,"extension":325,"meta":1150,"navigation":327,"path":332,"publishedAt":329,"relatedArticles":1151,"seo":1152,"stem":1153,"updatedAt":335,"__hash__":1154},"knowledge_en\u002Fen\u002Flearn\u002Fwhat-is-gga.md","What is GGA and why do I need to enable it?",{"type":9,"value":748,"toc":1137},[749,753,760,768,771,775,778,782,866,871,874,984,990,994,1026,1030,1048,1052,1055,1115,1119],[12,750,752],{"id":751},"what-gga-is","What GGA is",[17,754,755,756,759],{},"GGA stands for ",[79,757,758],{},"Global Positioning System Fix Data",". It is one of several standardised NMEA 0183 sentences — short text strings that GPS and GNSS receivers use to report position and status information. You have probably seen NMEA sentences if you have ever looked at raw receiver output: they begin with a dollar sign and are comma-separated.",[17,761,762,763,767],{},"In the context of NTRIP, GGA has a specific role: it is the sentence your device sends ",[764,765,766],"em",{},"to the server"," — in the opposite direction from the correction data — to tell the server where you are. This is unusual because most NTRIP communication is one-way (server to rover), but VRS requires this two-way exchange.",[17,769,770],{},"GGA does not need to be accurate to centimetre level for NTRIP to work correctly. A Single or Float solution position — accurate to a few metres — is more than sufficient. The server only needs to know which part of the network you are in, not your exact position.",[12,772,774],{"id":773},"what-a-gga-sentence-contains","What a GGA sentence contains",[17,776,777],{},"A typical GGA sentence looks like this. Each comma-separated field carries a specific piece of information:",[779,780],"terminal-box",{"additionalstyles":560,"items":781},"Example GGA sentence|$GPGGA,123519,5230.000,N,00452.000,E,4,09,0.9,25.4,M,46.9,M,,*47",[49,783,784,794],{},[52,785,786],{},[55,787,788,791],{},[58,789,790],{},"Field",[58,792,793],{},"Meaning",[71,795,796,807,817,827,836,846,856],{},[55,797,798,804],{},[76,799,800],{},[801,802,803],"code",{},"123519",[76,805,806],{},"UTC time — 12:35:19",[55,808,809,814],{},[76,810,811],{},[801,812,813],{},"5230.000,N",[76,815,816],{},"Latitude — 52° 30.000' North (Netherlands)",[55,818,819,824],{},[76,820,821],{},[801,822,823],{},"00452.000,E",[76,825,826],{},"Longitude — 4° 52.000' East",[55,828,829,833],{},[76,830,831],{},[801,832,294],{},[76,834,835],{},"Fix quality — 4 = RTK Fixed (see table below)",[55,837,838,843],{},[76,839,840],{},[801,841,842],{},"09",[76,844,845],{},"Number of satellites in use",[55,847,848,853],{},[76,849,850],{},[801,851,852],{},"0.9",[76,854,855],{},"HDOP — horizontal dilution of precision",[55,857,858,863],{},[76,859,860],{},[801,861,862],{},"25.4,M",[76,864,865],{},"Altitude above mean sea level in metres",[867,868,870],"h3",{"id":869},"fix-quality-values","Fix quality values",[17,872,873],{},"The fix quality field in GGA tells the NTRIP server — and any other system reading the output — what kind of position solution your receiver currently has:",[49,875,876,891],{},[52,877,878],{},[55,879,880,883,885,888],{},[58,881,882],{},"Value",[58,884,793],{},[58,886,887],{},"Typical accuracy",[58,889,890],{},"Suitable for VRS?",[71,892,893,909,924,939,954,968],{},[55,894,895,900,903,906],{},[76,896,897],{},[801,898,899],{},"0",[76,901,902],{},"No fix",[76,904,905],{},"—",[76,907,908],{},"No — position is invalid",[55,910,911,915,918,921],{},[76,912,913],{},[801,914,273],{},[76,916,917],{},"GPS fix (Single)",[76,919,920],{},"2–5 m",[76,922,923],{},"Yes — good enough to locate in network",[55,925,926,930,933,936],{},[76,927,928],{},[801,929,280],{},[76,931,932],{},"DGPS fix",[76,934,935],{},"0.5–2 m",[76,937,938],{},"Yes",[55,940,941,945,948,951],{},[76,942,943],{},[801,944,294],{},[76,946,947],{},"RTK Fixed",[76,949,950],{},"1–3 cm",[76,952,953],{},"Yes — best quality GGA",[55,955,956,960,963,966],{},[76,957,958],{},[801,959,301],{},[76,961,962],{},"RTK Float",[76,964,965],{},"0.1–1 m",[76,967,938],{},[55,969,970,975,978,981],{},[76,971,972],{},[801,973,974],{},"6",[76,976,977],{},"Dead reckoning",[76,979,980],{},"Variable",[76,982,983],{},"Depends on accuracy",[183,985,987],{"additionalstyles":26,"color":421,"title":986},"You do not need Fix before sending GGA",[17,988,989],{},"A common misunderstanding is that GGA only works when you already have RTK Fix. In fact, a Single solution (quality 1) is perfectly sufficient. Send GGA as soon as your receiver has any valid position — this allows VRS to start generating corrections, which then helps you get Fix.",[12,991,993],{"id":992},"how-gga-enables-vrs","How GGA enables VRS",[268,995,996,1002,1008,1014,1020],{"additionalstyles":26},[271,997,999],{"marker":273,"title":998},"Your receiver gets a rough position",[17,1000,1001],{},"Within 30–60 seconds of powering on outdoors, your receiver acquires satellite signals and computes a Single solution — typically accurate to 2–5 metres. This is enough.",[271,1003,1005],{"marker":280,"title":1004},"Your NTRIP client sends GGA to the server",[17,1006,1007],{},"Your client connects to the VRS mountpoint and immediately sends the GGA sentence containing your rough position. Most clients send GGA once on connection and then again every 10–60 seconds to account for movement.",[271,1009,1011],{"marker":287,"title":1010},"The server identifies your location in the network",[17,1012,1013],{},"The VRS server reads the latitude and longitude from your GGA sentence and determines which surrounding physical reference stations apply to your area. This computation takes less than a second.",[271,1015,1017],{"marker":294,"title":1016},"A virtual station is generated near you",[17,1018,1019],{},"The server synthesises an RTCM3 correction stream as if a base station existed 1–2 km from your position. It starts streaming this data back to your client immediately.",[271,1021,1023],{"marker":301,"title":1022},"Your receiver achieves RTK Fixed",[17,1024,1025],{},"With local-quality corrections flowing, your receiver resolves carrier phase ambiguities and reaches Fixed — typically within 10–60 seconds in good sky conditions.",[12,1027,1029],{"id":1028},"when-gga-is-required-vs-optional","When GGA is required vs optional",[167,1031,1032,1036,1040,1044],{"additionalstyles":26},[170,1033],{"text":1034,"title":1035},"Any mountpoint labelled VRS, MAC or a similar network correction type. The server cannot generate a virtual station without your position.","GGA required — VRS mountpoints",[170,1037],{"text":1038,"title":1039},"Some NTRIP services select the closest physical station automatically based on your GGA position, rather than requiring you to choose a mountpoint manually.","GGA required — nearest-station auto-selection",[170,1041],{"text":1042,"title":1043},"When connecting to a fixed mountpoint like RTCM3_NL, the server streams corrections regardless of whether GGA is sent. You can enable GGA for logging purposes but it is not used.","GGA optional — standard single-station mountpoints",[170,1045],{"text":1046,"title":1047},"When using your own base-rover configuration without NTRIP, GGA is not involved in the correction exchange at all.","GGA optional — own base station setups",[12,1049,1051],{"id":1050},"how-to-enable-gga-on-your-device","How to enable GGA on your device",[17,1053,1054],{},"The setting name varies between NTRIP clients, but the function is the same on all of them.",[573,1056,1058,1068,1078,1085,1093,1102,1109],{"additionalstyles":26,"items":1057},"Emlid Flow|SW Maps|FieldGenius|Trimble Access|DJI Pilot 2|Lefebure NTRIP|Leica Captivate",[577,1059,1060],{"name":579},[17,1061,629,1062,1064,1065,1067],{},[79,1063,585],{},", select your VRS mountpoint and enable ",[79,1066,589],{},". Connect after the receiver has a valid Single solution.",[577,1069,1070],{"name":603},[17,1071,582,1072,1074,1075,1077],{},[79,1073,608],{},", select the VRS mountpoint and enable ",[79,1076,612],{}," before connecting.",[577,1079,1080],{"name":616},[17,1081,582,1082,1084],{},[79,1083,622],{},". Select the VRS source and enable GGA transmission in the data-link settings.",[577,1086,1087],{"name":593},[17,1088,1089,1090,1092],{},"Enter the VRS mountpoint in ",[79,1091,599],{},". Trimble Access sends GGA automatically while NTRIP is active.",[577,1094,1096],{"name":1095},"DJI Pilot 2",[17,1097,1098,1099,1101],{},"Enter the VRS mountpoint under ",[79,1100,632],{},". DJI sends GGA automatically after it has GPS lock, so configure it outdoors.",[577,1103,1104],{"name":636},[17,1105,639,1106,1108],{},[79,1107,642],{}," and select the receiver or internal GPS as the GGA source.",[577,1110,1112],{"name":1111},"Leica Captivate",[17,1113,1114],{},"In the internet connection or rover settings, select the VRS mountpoint and enable NMEA GGA output to the NTRIP caster.",[12,1116,1118],{"id":1117},"gga-troubleshooting","GGA troubleshooting",[167,1120,1121,1125,1129,1133],{"additionalstyles":26},[170,1122],{"text":1123,"title":1124},"The connection is established but no corrections are flowing. This almost always means GGA is not being sent — or is being sent with quality 0 (no fix). Enable GGA, ensure the receiver has at least a Single solution, then reconnect.","Connected to VRS but 0 bytes per second",[170,1126],{"text":1127,"title":1128},"If corrections are flowing but Fix takes many minutes, the GGA position may have had low quality at connection time. Disconnect, wait for a better Single solution outdoors, then reconnect.","GGA sent but Fix is very slow",[170,1130],{"text":1131,"title":1132},"Most NTRIP clients send GGA periodically — every 5–60 seconds. The server receives updated positions and adjusts the virtual station to follow you. You do not need to reconnect when moving around the network coverage area.","Moving between areas — does GGA update?",[170,1134],{"text":1135,"title":1136},"GGA contains only your approximate position, altitude, satellite count and fix quality. It contains no personal identifiers; the NTRIP server uses it only to route corrections.","Privacy note",{"title":313,"searchDepth":314,"depth":314,"links":1138},[1139,1140,1144,1145,1146,1147],{"id":751,"depth":314,"text":752},{"id":773,"depth":314,"text":774,"children":1141},[1142],{"id":869,"depth":1143,"text":870},3,{"id":992,"depth":314,"text":993},{"id":1028,"depth":314,"text":1029},{"id":1050,"depth":314,"text":1051},{"id":1117,"depth":314,"text":1118},"learn\u002Fwhat-is-gga.webp","GGA is a short position message your device sends to the NTRIP server. For standard mountpoints it is optional. For VRS mountpoints it is mandatory — without it the server cannot generate corrections and streams nothing back. This is the single most common reason VRS appears to connect but delivers no Fix.",{},[331,739],{"title":746,"description":1149},"en\u002Flearn\u002Fwhat-is-gga","HFG0RJGp9bO8FHQR5HkzNRVEiSqOCSmiRVEfH3EUQ58",1787304715512]