# Questions tagged [gps]

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

320 questions with no upvoted or accepted answers
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### Get rid of jumping GPS data with pykalman

I have gps data that I get from a smartphone application. Whenever the smartphone is stationary, the gps points are jumping. I understand that the signal is inaccurate due to the reception in a city ...
• 191
272 views

### Position of vehicles relative to lead vehicle

I have a set of vehicles (think railway) that are in a (semi)fixed formation. I know the lead vehicle and I know the GPS coordinates of the lead vehicle at any given time. Sometimes, I can rely on the ...
• 181
10k views

### Translating hdop, pdop and vdop to metric accuracy from given NMEA strings

How can I translate dilution of precision to a metric unit? For example: say I got 1.2 in hdop from NMEA sentence of my GPS receiver, in what should I multiply to get a metric accuracy? Just like the ...
545 views

### Math formula to calculate GPS location for weighted GPS data points

I'm working to improve the location and accuracy of a map / data-point driven application. I have a collection of locations of interest. Each location of interest has a collection of data points that ...
• 161
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### Acquire ground coordinates of target while doing aerial survey (airplane or helicopter)

The Problem: Each year I board a small airplane and look for diseased individual trees while flying transects over the forest I help manage. The current method for marking a tree's location is ...
• 61
302 views

I want to filter the GPS data. when I use the low cost GPS receiver, it gives erroneous data. therefore I want to apply some filtering technique. How can I read ephemeris data from GPS receiver? I ...
• 73
2k views

### How to approximate point to segment distance on sphere?

I would like to approximate the distance of a line segment from a reference point on the map (coordinates are gives as lat/lon). In the Cartesian coordinate system I would simply find the closest ...
• 141
139 views

### How to detect curves and straight paths using GPS coordinates?

I'm working on a project involving railway tracks and I'm trying to find an algorithm that could detect curves(left/right) or straight lines based on time-series GPS coordinates. The data contains ...
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274 views

### Separate NMEA String in QGIS for position tracking

I'm using a tracking system that exports positions as NMEA strings output by a single COM port. Each string has a unique identifier ("001", "002", "003") that represents ...
• 101
533 views

### How do I read the GPS data from a GPS device using Java

I want to read data from a GPS device connected to my laptop and find the latitude and longitude. I searched a lot about it but could only find Android related programs. How do I read the GPS data ...
562 views

### WSG84, GPS, GEOID and other altitudes

INTRO A bit of tool introduction, but the problem is not related to this directly. I have an app in CesiumJS. I am using Cesium World Terrain, and get altitude using Sample Terrain Most Detailed ...
• 121
15k views

I downloaded Google location timeline history. However, this data is represented as a polyline with just about a dozen time marks (Figure 2). At the same time when I look at the Google location ...
679 views

### Store live tracked GPS points with additional attributes (alitude, DOP, accuracy)

I am using the Live GPS tracking feature from QGIS (GPS Information Panel). For a project I need to collect points in the field and directly see and store them in QGIS. For this I have a setup of a ...
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352 views

### Import GPS SINEX (for velocity analysis) into Sarscape or processing with others software

I try to import GPS snx. into Sarscape 5.2 (use GPS Import tool) and getting error 115) ) gps_type : [sinex] 116) ) generate_kml : [OK] 117) ) generate_shape : [OK] 118) ) ...
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480 views

### High-level method for offline future road elevation data

I am new to GIS, so please do not hesitate to call me out in providing limited information. I have a .tiff Terrain (elevation) data file for the east coast of the US and a .osm.pbf OSM file for ...
155 views

### Understanding Latitude Jumps

I'm decoding some AIS messages and outputting KML files showing routes. Looking at some ships in the Adriatic Sea there are some weird Latitude jumps that I don't understand. Several ships show ...
• 187
724 views

### Is it possible to display labels in background files (.imp) on Trimble GPS units?

I have been trying to figure out if this is possible for a while now. I know if you load a file in as a data file, you can click on a feature and the label will pop up. However, you cannot view a data ...
• 31
997 views

### GLONASS Satellite Position Prediction using Almanac Data

GLONASS ICD has a section named "Algorithm of calculation of satellite motion parameters using almanac". It gives the formulas in order to calculate the position and velocity of the satellite. ...
• 141
1k views

### Should 2D Positions and 3D Positions be considered conceptually different entities?

Let's suppose we want to model GeographicPositions, described by coordinates or coordinate tuples inside some Coordinate Reference System. Also, these would be put inside some sequence to represent ...
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881 views

### QGIS: GPS Tracking with improved Altitude

I am preparing for archeological fieldwork in Sudan. I recently came up with RTK equipment and software using RTKlib to export the real time corrected data (cm level) to QGIS via a simulated NMEA ...
527 views

### Are there any shapefile-based GPS data recorders?

I am looking for a data recorder that can be programmed to send a serial data request to a field computer and then accept and record an incoming data string and tie it to GPS location and then save ...
777 views

### How to read a .GPB file in C#?

I have a .GPB file, I need to extract the common GPS data from it but I don't find a clear structure that specify the contents of that file. as a sample record from file 00000260 02 11 A9 61 E7 96 ...
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44 views

### How does a receiver locate with more than 4 satellites?

If it takes 4 equations to find x,y,z and t, how does one improve the accuracy by adding 5th equation or does it reuse any 3 previous equations and recalculate with the 5th equation?
116 views

### Is GPS data already filtered?

I was driving around in my car, with a GPS module on the roof. The data I collected is somewhat suspicious. The module I used is a standalone GPS module (L80-M39) integrated into a PiHat LORA-module. ...
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### Calculate nearest point in a orbital path to user (GPS)

TLDR: how do I go about determining the nearest point in an orbital path to a user's location? Longer version: This is gonna remain a bit vague, I'm uncertain of the terminology needed to ask/answer ...
433 views

### Calculating coordinates of two GPS points whose line through them is perpendicular to two other GPS points

Given two GPS points A and B, I would like to compute the GPS coordinates A1 and A2. [A1A2] forms a segment perpendicular to segment [AB]. For this, I start to compute M1, which is the midpoint ...
• 121
275 views

### Activating the GPS on QField for Windows Desktop (beta)

Has anyone figured out how to activate the GPS on the computer to use in QField-Windows? I have a Getac field tablet/computer. I've created a QGIS Project with 3 vector layers and packaged for QField. ...
52 views

### Showing multiple GPS devices at the same time in QGIS

Is it possible to show multiple live GPS devices at the same time in QGIS?
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### How is Trimble Pathfinder Office transforming positions?

I am struggling to understand how Trimble’s Pathfinder Office transforms and exports GNSS data and I’m hoping someone here can explain. I've seen posts like this and this, and documents like this, but ...
53 views

### Under which condition(s) does geopositioning precision infer accuracy?

I am not sure whether this is the right forum for this question but I reckon that since it gathers experts in GIS, the odds of someone having valuable insights is higher than anywhere else. So here's ...
444 views

### How to interpret gpsd TPV accuracy info

I want to understand the epx (Longitude error estimate in meters, 95% confidence) and epy (Latitude error estimate in meters, 95% confidence) values in a gpsd TPV packet. If I have data like this { &...
• 71
145 views

### Calculating the coordinates of the selected pixel point from an image with known corner coordinates

How can I calculate the coordinates of the point(P) we want from an image with known corner coordinates? I want to find out respective coordinates from the selected the pixel of the image obtained ...
394 views

### GPS emulators on Linux/Windows

I'd like to know if there are any GPS emulators available? What I'd like to do is the following: Given a series of straight lines and a vehicle moving at a certain velocity on the lines, I'd like the ...
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35 views

### Pseudo-range computing

I have to compute the relative pseudo-range for my student job, unfortunately, nobody can help me because they are not read into the topic enough. So I'm asking here: My receiver has to have a 1500 ...
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314 views

### Aggregating DateTime and GPS latitude/longitude

I have a dataframe with multiple columns including SerialNumber, DateTime, GPS latitude and GPS longitude. Background: Tractors marked with Serial numbers are working(driving) on fields, sending data ...
• 195
158 views

### What is the best way to calculate the accuracy of GPS point measurements in relation to the road network?

I have a vector dataset containing GPS locations/points of different vehicles and a (polygon) road network dataset. Due to the inaccuracy of the GPS receiver, these gps points can deviate up to 10-20 ...
• 509
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### Putting locator from GPS coordinates in 3D projected map

I'm new to maps and not so good in math and geometrics. I have a 2d google map. I have to put a 2d projection of this map (not exactly this one but a handpainted one, so I will not violate any ...
• 129
568 views

### Calculating Center (GPS Point) and Radius (km) of n GPS points

I'm new to GPS and position mapping but i have a background in programing and some of the math related to it. I've been tasked with writing a small golang program that takes n GPS points (DMS) and ...
• 121
253 views

### What is causing this shift in coordinates?

I'm working on taking raw GPS measurements and getting a position from them. It involves double differencing measurements from a fixed base station (with a known position) and a rover (in my case, an ...
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47 views

### Updating local datum to latest ITRF?

I have read that Australia is updating its local reference frame. If a small territory has a complete CORS GNSS network aligned to ITRF2000, does it need to update the CORS network to the latest ...
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97 views

### Receiving strange characters from GPS tracker, is this HEX or binary?

I am struggling with a GSM GPS tracker. It looks like a clone of GT02A, and it is a relatively common model. My problem is that when it sends data to my server, it is not readable. I set it to send ...
• 141
57 views

### Can I correct position data from a device suffering from the 4/6/19 roll-over problem?

I work for a company that sells apparatus containing GPS receivers. Over the years a lot of this gear has been sold and deployed. A number of machines in the field contain GPS receivers that feature ...
• 121
94 views

### QGIS, polygons and GPS

I intend to use QGIS 3.6 as a tool for archaeological field works, live tracking. I have created a form and everything works great except for creating polygons. I have installed QGIS on a Panasonic ...
758 views

### Calculate Galileo satellite position from Ephemeris data

I'm trying to calculate Galileo stallite's position from ephemerides data. I'm reading from https://gssc.esa.int/navipedia/GNSS_Book/ESA_GNSS-Book_TM-23_Vol_I.pdf at 3.3.1. The first step is: ...
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25 views

### Filter pictures in directory

I have a drone project with 50,000 pictures in 50 layers. Each layer has 2 to 5 zones. When I put them all together, we have a lot of overlap and in some places, we have up to 4 pictures of the same ...
411 views

### calculating HRMS using NMEA sentences including GPGGA , GPGSV, GLGSV, QZGSV,QZGSA, GPGSA?

I have NMEA sentences including GPGGA , GPGSV, GLGSV, QZGSV,QZGSA, GPGSA and GNGSA. my goal is to achieve HRMS accuracy meter. produced android devices for special intent gives GP/GN GST nmea message ...
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### Does GPGGA have leap second correction?

I'm trying to use GPS clocks to synchronize some measurements and I'm a little confused about the leap second correction between GPS time and UTC. I was wondering - does the GPGGA NMEA header have the ...
94 views

### Very different static gps tests for different devices

I don't understand the results that I got when I measured with three different devices that were lying on the ground for couple of hours. These devices were: Nexus 10 tablet, Samsung Galaxy Core Prime ...
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