Questions tagged [gps]

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

243 questions with no upvoted or accepted answers
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151 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 ...
5
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185 views

Determining Bounding Points of UAV Images

I know the EXIF data from drones contains the GPS point central to the photo to provide photo location. What I'd like is to determine the lat/lon of the four corners of the image. I've done a pretty ...
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2k views

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 ...
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1k views

Importing GPX data to PostGIS table

I'm implementing a recipe from Paolo Corti's PostGIS Cookbook (by the way, a great help!) in order to import track points from multiple GPX files into a PostGIS table in two steps (pages 87-88): 1 ...
5
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8k 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 ...
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31 views

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 ...
4
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1answer
113 views

Cleaning GPS tracks from large jump / outliers

Can someone please explain the steps to take in order to eliminate the parts of these linestrings which jump across large distances (not along with the road network)? They were created from GPS ...
4
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240 views

Reading ephemeris data from GPS receiver?

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 ...
3
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1answer
108 views

Is the GPS signal being scrambled near military bases

We are navigating our survey aircraft using standard GPS receiver. Sometimes we fly near the vicinity of US Ramstein military base in Germany and it seems we are losing lock (no solution) in that area ...
3
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10k views

How to download Google location timeline raw data (red dots)?

So 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 ...
3
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315 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) ) ...
3
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114 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 ...
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654 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 ...
3
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841 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. ...
3
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802 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 ...
3
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789 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 ...
3
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491 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 ...
3
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718 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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49 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 ...
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2answers
55 views

Ignoring ellipsoidal heights recorded from GPS when only interested in location?

I am not interested in converting ellipsoidal height into AHD heights, because I have a good DEM. However, this whole business about geocentric vs geodesic coordinate systems is thoroughly confusing ...
2
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1answer
45 views

Options for precise relative position calculations

I'm investigating an industrial application that has a requirement to calculate with precision the relative distance on the ground between two outdoor points in the following scenario: The first ...
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0answers
98 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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26 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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30 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 ...
2
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55 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 ...
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70 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 ...
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235 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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23 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 ...
2
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1answer
228 views

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 ...
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85 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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0answers
92 views

Garmin GPSMap 64S deleting waypoints?

So I'll start off by saying I'm still in the rookie stages of GIS work. But I have a GPSMap 64S and for work I had to go out and collect waypoints of an area. No problem, all was good and well, got ...
2
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0answers
98 views

Problems when converting KML files to GPX

Looking at the KML and the GPX file that I created (in QGIS through 'Save as'), in QGIS it looks as if the lines are all right (picture 1), but when I open it in another type of GPS program like ...
2
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1answer
3k views

Maximum GPS-based location Sampling rate of smartphones

I am working on Android application that needs to take GPS locations at the rate of 10Hz to 1Hz. I tried it by setting 100ms for time interval for requestLocationUpdates(_, 100, _, _) function. But ...
2
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74 views

Where exactly is the GPS position located on a GPS device?

I have a very precise GPS which in theory when using RTK achieves 2cm accuracy when reporting its GPS position. But where exactly on the GPS device is this position? In other words, when the GPS ...
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89 views

How can I change QGIS GPS tracker symbol?

I may look stupid, but can't the find place where I can change GPS live tracking symbol. I use GPS tool in fieldworks with forest orthophotos and default symbol that displays my location (black circle ...
2
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0answers
671 views

Record a GPS track in qfield?

Okay I can't figure out for the life of me how to log a live GPS track in qfield. I can add points and draw polygons, both of which are useful, but how does one track? I am trying to use qfield to ...
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0answers
1k views

What is a Trimble .CAR file?

I have a field team using a Trimble Geo XH from 2008. My usual workflow is to have them email me the raw GPS files, which I copy into a "GIS Folder" for import to Pathfinder where I process it. I ...
2
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0answers
378 views

Plotting realtime .nmea files with QGIS 2.18.10

I am working on a project that requires us to track 2 GPS targets, one car and one weather balloon. The realtime GPS tracking of the car via the COM port works great. The decoded data from our weather ...
2
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0answers
361 views

Getting Latitude and Longitude using GPS Averaging app on android phone?

I am trying to get latitude and longitude of radio stations across my country (Liberia) using an Android phone. I downloaded GPS Averaging but I keep getting an error which says: NO GPS SIGNAL How ...
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0answers
677 views

How to calculate elevation of the point?

I have two points: A ( x1 ( latitude ), y1 ( longitude ), z1 ( elevation ) ) and B ( x2, y2, z2 ). x1,y1,z1 and x2,y2 are known, also I know the distance between A and B. How can I calculate z2 ...
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0answers
516 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 ...
2
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0answers
140 views

How was GPS not freely available for civilian use before 1983

In 1983 GPS was made freely available for civilian use, https://en.wikipedia.org/wiki/Global_Positioning_System: President Ronald Reagan issued a directive making GPS freely available for ...
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980 views

Height above sea level measurement

I would like to use height above sea level in the gravity equations. What is the source for getting it? Can i use altitude measurements from Altimeter or GPS 'z' measurement? For your kind information,...
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0answers
44 views

GPS accuracy for blind person O&M

I would like to be able to use GPS on my phone, in conjunction with an app, to enable O&M (Orientation and Mobility) support, on my device. I want the app to tell a blind person walking along a ...
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0answers
1k views

How to calculate all distance from GPS route using date time and coordinates for php?

I have big GPS data which have 4 columns for id, date time, lat, long. I wanna implement Haversine's formula to get distance between 2 nodes. But if I want to find all distance from start to last ...
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0answers
544 views

How to compare a theoretical GPS route and a real one?

In an iPhone app, I'm trying to generate a roadbook automatically based on a real recorded route. I have figured out an algorithm to use a directions service to do it, but my algorithm needs to be ...
2
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0answers
301 views

Multiple gps tracking in QGIS?

I was wondering if someone could point me in the direction of display the output of multiple gps devices at the same time in QGIS. I have two GPS devices that are both outputting NMEA sentences ...
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0answers
71 views

How to count near intersecting polylines and merge them?

I have a dataset with several polylines created by GPS points of car trips. I am trying to create a simple heatmap where roads with more traffic (where polylines intersect) get darker. I already ...
2
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321 views

How can I position gps point on svg (or any other special type if exist) scheme of building?

I have an indoor map of a building in svg and this is an only scheme of a building, there is no google maps or any other maps. But I need positioning (navigation) by gps coordinates in this scheme. ...
2
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0answers
2k views

Convert GPX/KMZ to google maps directions

Is there a way to convert a set of waypoints in a GPX/KMZ file to driving directions suitable for Google Maps. There are numerous sites listing community generated routes which I am unable to load ...