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Questions tagged [gps]

This tag refers generically to any space-based satellite navigation system that provides location and time information.

The GPS tag refers generically to any space-based satellite navigation system that provides location and time information. These are properly known as global navigation satellite systems, or GNSS.

Technically, GPS refers to the specific GNSS system run by the United States known as the Global Positioning System. However, the term is often used generically to refer to other GNSS systems such as GLONASS of Russia (see GNSS link above for others) or the concept of satellite-based locating services in general.

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Why does GPS positioning require four satellites?

I have a question on the GPS positioning algorithm. In all books I've read for 3D positioning we need four satellites, and I don't understand why. We need to calculate three variables: x, y, z. We know when satellite send the signal to earth and…
matekm
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Does an earthquake affect GPS?

There are news reports saying that the Sendai earthquake a couple days ago has shifted the earth on its axis and moved the island 8 feet. Last year, there were similar reports with the earthquake in Chile. Does this affect GPS devices at all? Is an…
Rebecca Chernoff
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What are the major differences between GPS, GLONASS and Galileo?

What are the major differences between GPS, GLONASS, COMPASS and Galileo?
JamesRyan
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How to parse EXIF GPS information to lat,lng decimal numbers

"EXIF_GPSAltitude": "(220.279)", "EXIF_GPSLatitude": "(55) (40.711) (0)", "EXIF_GPSLatitudeRef": "N", "EXIF_GPSLongitude": "(8) (30.2282) (0)", How should i understand the above example as degree, min, sec? Some EXIF data that I extracted has…
Poul K. Sørensen
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How do GPS/Glonass/Galileo satellite know their position?

We use satellites to calculate our position. How do satellites know their position if it is right or wrong ? I have heard that the base station records and corrects the satellite path but how do they know what is right path what is wrong path ?
Abhijit Gujar
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Why is getting GPS fix so slow?

I understand the basic concepts of GPS positioning system and the use of trilateration but I don't understand why it takes so much time to get a fix. On commercial GPS like TomTom it usually takes about one minute and on my phone it can take more…
Martin Trigaux
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GPS to map workflow, for non-GIS folk

What applications and workflow(s) do you use for gathering, displaying and storing GPS data, with your centralised corporate data, for people who are not GIS folk? We're in the process of standardizing across all branch offices and I'd like to hear…
matt wilkie
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Does GPS signal quality depend on the chip manufacturer? Does it depend on weather?

(Sorry if GIS is not the right place to post this question to). Recently me and my school friends had a GPS software application project to pursue at the university. A device very similar to this one was used by the application. One day it refused…
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Does the strength of GPS weaken in rural areas?

Does the strength of GPS weaken in rural areas? For example, based on how the satellites work, would the strength in the centre of Australia differ from a populated city in Europe?
S-K'
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Reasoning behind GPS time week number?

So the GPS Week Number rollover has been all over the news lately. I don't really know anything about GPS, but my first thought upon reading up on this topic was: why use a week-based format in the first place? It seems like it would have been much…
Andrea
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What is the origin of the term "kinematic" in RTK?

Where does "Kinematic" in "Real Time Kinematic" (RTK) come from? Most litterature on RTK explains that it stands for Real Time Kinematic, but not why that name is used instead of something more descriptive like "real time carrier phase differential…
Erik
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Precision of x decimal points in meters?

Is there a handy reference that corelates the number of decimal points in a coordinate to the precision in meters? I had discussions like "4 decimal places will place you within a 500 meter radius" and "6 decimal places will place you in a house". I…
Jesvin Jose
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Can GNSS precision be improved with a local atomic clock?

Does the use of a local atomic clock improve the accuracy for position determination with existing GNSS?
Nick Russler
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Accuracies of various GNSS systems

I was looking for a comparitive statement of the accuracies achived by various GNSS systems such as QNSS, COMPASS, GLONASS, GPS..etc. however i find only discriptions of only GPS everywhere
userX
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How do I calculate a xyz-position of one GPS position relative to another?

I have two GPS positions (lon, lat, alt) and want to get the position of one relative to the other one. (in meters, as x, y, z) How do I do that? Edit: The locations have a distance of up to three kilometers And: I do NOT just want the distance.
Lara
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