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

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Local Coordinate to Geocentric

The ultimate question, I need a transformation matrix to take a point in local space representing a roughly 500m x 500m place in New Mexico centered at -108.619987456 long 36.234600064 lat. The final ...
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11answers
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Device for Logging GPS and Accelerometer Data?

I am looking for a device that can track my location (lat,long) and speed all day long. Perhaps, I need GPS and accelerometer data bundled together. What I want to do is to log my daily activities. I ...
11
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5answers
2k views

How to build a geographic database of GPS logs?

On our aerial wildlife surveys we typically generate dozens of GPX files, and usually convert most of them into shapefiles for display in a GIS application. GPX files are a terrific way of keeping all ...
11
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5answers
10k views

Convert XY points to a line?

Someone mistakenly saved a GPS track as waypoints and then sent them along to me in a .csv file. They want a line back (shapefile). What's the simplest method to convert this to a line? Available ...
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7answers
9k views

Is there a good GPS track analysis library?

I keep writing custom code to work with GPS tracks: GPX files and NMEA logs from my phone, dedicated GPS logger, etc. I feel like I'm reinventing the wheel and am wondering if there's some standard ...
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4answers
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What is the maximum Theoretical accuracy of GPS?

I was talking with a potential client, and they requested that we plot some points with GPS, with a maximum (or should that be minimum?) accuracy of 2 m. This is an area with no WAAS, and I was under ...
9
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1answer
884 views

What causes the GPS offset/shift in China?

I've spent close to two full days trying to understand the nature of the infamous GPS shift in China. After sifting through the noise, two recurring symptoms are that: GPS coordinates (WGS-84) plot ...
4
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3answers
1k views

Mobile, Offline viewer for geographic data

Currently, field crews consumer geographic data via laptop (no internet, no gps). ArcReader. I would like to get them shapefiles (or some derivative of a shapefile) on a mobile platform (smartphone) ...
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1answer
1k views

How do I calculate ECEF X,Y,Z velocities for GPS if I have no satellites

I'm attempting to simulate a GPS message where know variables are starting location, ending location, speed (m/s), and a bearing (0 - 359 degrees). How can I calculate the ECEF X, Y, Z velocities ...
3
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1answer
231 views

Automatically panning the map in ArcGIS when using the Time slider

I have a point dataset with time-stamps at 1 minute intervals showing a driving route. I have enabled the Time properties of the layer and I am able to use the Time slider to see the points move ...
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4answers
5k views

Can *.ssf files from Trimble GPS be imported as features to display in ArcMap?

I have not come across *.ssf files before but I believe they are a Trimble GPS binary format. Someone has asked me if these files which he thinks have line/poly features can be imported for display ...
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6answers
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Sources of realtime spatial data

I'm trying to set up a demo that serves up live spatial data, but am having trouble finding any suitable example data sources. Ideally I'm looking for something that updates every few seconds; either ...
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3answers
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Post Processing GPS Data with open source software

I am using Magellan Professional Mapper CX working on ArcPad 7.1 platform. It has sub-meter accuracy after post processing. Without post processing the data collected in the field is off by 10 to 15 ...
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10answers
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Need a Benchmark GPS Trajectory data-set? Anyone?

I'm looking for a benchmark GPS data set, available for research purposes for free. I've found GeoLife GPS Trajectories dataset from Microsoft Research but I find it a little incomplete. What I need ...
3
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3answers
7k views

Distance between GPS coordinates

Given a database of GPS points, a center GPS location, and a radius R (in meters), how can I find all points in the database that are within a distance of R of the center point? Will the distance ...
35
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12answers
27k views

Tablet or smart phone GPS vs “real” GPS

I've been reading a lot today about android and iphone devices being used for spatial data collection in the field and it sure seems to be that single purpose devices such as the extremely popular ...
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6answers
5k views

How to create a polyline-based “heatmap” from GPS tracks?

This winter I am planning to track my downhill skiing/snowboarding using a GPS. Most of my riding will occur at the same resort. I would like to be able to create a sort of "heatmap" that shows the ...
13
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5answers
8k views

How to get an elevation profile for a gps track?

I'd like to get a reasonably accurate elevation profile for a track recorded with a GPS (which often has very unreliable altitude data and occasionally none at all, depending on the model.) Does ...
15
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12answers
4k views

Mobile Data collection options

What COTS software is available to do mobile data collection, with GPS positioning. Map display not required. I'm looking across the board (platform wise). I'm already aware of... RhinoSpect ...
35
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9answers
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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 ...
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2answers
21k views

Differences between triangulation and trilateration?

Looking around I noticed that many people interchange the terms (triangulation and trilateration) for the same sense. What is the correct sense of Triangulation and what are the differences from ...
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2answers
3k views

Using OpenLayers (with OpenStreetMaps) and PostGis for rendering data acquired from GPS tracking device?

I'm researching and planing to acquire data from GPS device and store them in postGIS database, then use geodjango to process/work them out and finally chart them on a map with OpenLayers. Will these ...
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2answers
4k views

What algorithm should I use to remove outliers in trace data?

I have GPX traces and want to remove outlying observations. There are some route points that are impossible because it would require acceleration that the vehicle can not achieve. Are there good ...
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2answers
1k views

Storing GPS tracks with timestamps in PostGIS

I need to store a series of GPS points with timestamps in the database (traces of various vehicles). I am wondering which of two approaches to choose for storing them in the PostGIS table: 1.) Each ...
7
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4answers
510 views

Is there a way to identify and remove similar GPS tracks in PostGIS or ArcGIS?

I have a large number of GPS tracks from a number of different users. I'd like to identify tracks that take the same route and remove those duplicates. For example, a user takes the same streets from ...
6
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2answers
731 views

Managing error with GPS routes (theoretical framework?)

I'm looking for the appropriate theoretical framework or speciality to help me deal with understanding how to deal with the errors that the GPS system has - especially when dealing with routes. ...
0
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2answers
289 views

how to load gps information in my map and track way points?

i am using QGIS 1.8 in ubuntu 12.04 . i am working with ROBOTIC OPERATING SYSTEM(ROS) and QGIS simultaneously . My ROS system is connected to LIDAR(sensors) that will publish gps message so i could ...
2
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2answers
510 views

Automating the production of GPS-compatible map tiles from georeferenced raster maps

I have a set of TIFF maps that I want to load onto Garmin GPS 62s units. The maximum size for each tile on the GPS is 3Mb and less than 1 million pixels. I manually produced one tile, following this ...
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2answers
6k views

How to export and import gps points from Garmin 62S and QGIS

I'm pretty new to using QGIS and I'm curious about how to import and export GPS points created in QGIS. I have QGIS 2.0.1 dufour on windows XP and a Garmin 62s. Any suggested walk throughs would be ...
0
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1answer
7k views

Convert Degree Minutes to decimal degrees [duplicate]

I have location points collected from a garmin device stored in an excel sheet in Degree Minutes format --- W00208.172,N1046.977. I am looking for an Excel formula to convert either to Decimal Degrees ...
16
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1answer
447 views

How can I statistically calculate the “real” road from a set of GPS tracks

I participate in a long-distance cycling club, and we started to collect GPS data routinely from our riders. My interest is to calculate "the real trajectory" for future events based on accumulated ...
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5answers
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How correct is the “Accuracy” value given by GPS devices?

I have a Garmin Forerunner 305 and a Google Nexus One Android phone. From the GPS on both these devices I can get a "Accuracy" value that is usually between 6-20 meters. How much can I trust this ...
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7answers
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Why don't they use cell towers like GPS satellites?

If my understanding is correct, a GPS satellite produces a pretty simple signal which is basically composed of its location and its time. Given 4 of these signals, then one can uniquely solve for the ...
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4answers
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Clustering Trajectories (GPS data of (x,y) points) and Mining the data

I've got 2 questions on analyzing a GPS dataset. 1) Extracting trajectories I have a huge database of recorded GPS coordinates of the form (latitude, longitude, date-time). According to date-time ...
12
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2answers
1k views

How much sense does it make to average (lat,lon) samples in order to increase 2D accuracy of a GPS location?

Several GPS applications, like this one, or this one, acquire multiple (lat,lon) samples of a given location, assuming that the GPS unit is not moving, and then take an average of the samples in order ...
16
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3answers
537 views

Lightsquared GPS controversy: Where is the analysis?

GPS World reports that Lightsquared's network of 40,000 transmitters will interfere with GPS signals. Initial technical analyses have shown that the distant, low-powered GPS signals would ...
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3answers
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Advanced android app for mapping and GPS logging

I am looking for an android app able to log GPS data like coordinates, altitude, current speed and would be nice if also the GPS accuracy/number of satellites. Many GPS apps are able to display these ...
12
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1answer
875 views

How to find ring of coverage of GPS Satellite on WGS-84 ellipsoid?

Given the following: Time, t The set of IS-200 Ephemeris data, E, of a GPS Satellite corresponding to time t The ECEF position of the GPS satellite, P=(x,y,z), derived from the time and ephemeris, ...
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3answers
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Calculate maximum speed from GPS data

I have raw GPS locations for a track, and need to get maximum speed. Simple methods (calculate speed between 2 points, take max) will give meaningless large numbers due to GPS inaccuracy, the point is ...
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4answers
4k views

What data is sent from GPS satellites to receivers?

I know more or less how the GPS system works. But I would like to understand it in more details. Exactly what data is sent from a GPS satellite to a GPS receiver? I think there is multiple types of ...
12
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2answers
543 views

Why does GPS altitude jump sometimes?

I am currently developing a little application in Android which uses GPS. When i click a button i start to record a "track". If i walk around i save my position every second into a file. This works ...
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4answers
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How to filter wrong GPS points?

I have a database of GPS points. There aren't any tracks, only points. I need to calculate some value for every 100 meters, but sometimes GPS gave a wrong coordinates that lies far from real GPS ...
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4answers
1k views

Matching GPS tracks

I'm looking for a proper way to process multiple GPS tracks (so time ordered list of lat/lon points) and match/classify that segments, that are covered by multiple tracks: So it's not about ...
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3answers
512 views

GPS and GIS for real time monitoring of an object

How is it possible to store coordinate of object in server in real time using feasible hardware ( can be used by student) GPS into database and retrived in real time?? What are the names of ...
12
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3answers
1k views

GPS Elephant Tracking: Utilizing A-GPS, WAAS, DGPS and Understanding HDOP, NSAT, and ZDA

*I'm using a GPS data logger (qstarz bt-q1000xt) to track the movement of zoo elephants, and I have a variety of technical questions. I've had limited success receiving answers from the vendor. You ...
7
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1answer
230 views

Analysis of GPS error

I'm wondering if there have been any studies which attempt to analyze or characterize GPS error distribution over different situations/conditions (e.g. surrounded by tall buildings/mountains, ...
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2answers
20k views

How to make work tablet integrated GNSS (GPS) on Windows 8 with QGIS?

I have tablet - Dell latitude 10, running Windows 8, with integrated Broadcom GNSS Receiver BCM47511 (GPS,Glonass...). Because it is integrated GPS and Windows 8, there is the "new" way of providing ...
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2answers
1k views

Trimble GeoXH vs GeoXT and GPS Correct

I am about to purchase a new GPS unit. I currently have a GeoXT and have used the combo of GPS Correct/ArcPad with GPS Analyst/ArcMap to correct the collected data to submeter (or close to it). ...
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1answer
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Calculating absolute precision confidence number from Dilution of Precision indicators from GPS receiver

End-user GPS receivers typically show an absolute confidence indication, such as Within 25 Metres, for the calculated position. I am parsing NMEA data from a GPS unit and wan't to calculate a similar ...
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2answers
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GPS Module Without Velocity or Altitude Limitations

I am looking for a GPS module that I can use in a high-altitude project. The problem I have discovered is that GPS manufacturers are required to place a set of restrictions on GPS modules. The ...