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

learn more… | top users | synonyms (2)

6
votes
1answer
189 views

GIS Server for web service

I am building an app that has some GIS requirements that go a little beyond (I think) what I can retrieve from existing online web services resources so I am attempting to build a server of my own to ...
6
votes
2answers
227 views

Survey Data to GIS database [closed]

This is a General Question on a possible workflow for Survey Data directly to ArcGIS In most GIS/Survey workflows there is a field collection team and backoffice GIS team. When the availability of ...
6
votes
2answers
2k 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). ...
5
votes
3answers
807 views

Tracking a vehicle without GPS device

We are planning to write an application which have to track the user driving in his truck in the cities like New York city accurate upto which lane he was driving on. In the cities with those tall ...
5
votes
2answers
2k views

Why is the GPS Reference Meridian 100m to the East of the Prime Meridian?

Apparently if you stand at Greenwich then your GPS will not say you are at longitude zero. This is because the GPS reference meridian is about 100 metres to the east of the prime meridian. My ...
5
votes
4answers
1k views

Looking for software to interface GPS data with PC

I have GPS Unit from Garmin (GPS 18xPC). I'm looking for software I can install on my PC that will allow me to interface with the data I collect on my GPS unit. Any help will be great
5
votes
5answers
320 views

Detecting and fixing outliers in a GPS trajectory

I need to find an algorithm or method that can detect outlier latitude longitude points in a trajectory during post-processing, which can then be fixed (brought back into the trajectory's path based ...
5
votes
1answer
302 views

Odd, old coordinate formatting from 1997 GPS

A typical coordinate is given as 68 35 067 N 123 54 817 W. I thought maybe some old timers could help me out. The author says in his report of the time that they were using a GPS, but I contacted ...
5
votes
2answers
1k views

Accuracy vs Precision GPS

I am doing some research on consumer grade GPS accuracy and precision. I took 5 readings for 20 known locations (100 readings). Am I correct in assuming that the standard deviation between the 5 ...
5
votes
2answers
475 views

gpspipe returns correct timestamp, but wrong date (21 dec 1995)

I'm having this strange issue where my gps pipe is returning the correct location and time but the wrong date (including year). For reference, at the time of writing it is 06 aug 2015, 09:27 UTC). ...
5
votes
3answers
438 views

How to calculate 'off track' error from GPS data?

I'd like to analyse navigational accuracy, comparing planned transects with the actual track flown from GPS data. For example, the planned transects below (green) don't match perfectly with the ...
5
votes
4answers
155 views

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
5
votes
2answers
114 views

Are speeds in GPS data obtained by detection or calculation?

I have been doing a study into taxi behavior with its GPS data. I could calculate taxi's mileage by either longitudes and latitudes or times and speeds in the data. Since there are several errors in ...
5
votes
1answer
2k views

What is required for post-processing differential correction? (And can Garmin units provide it?)

2 very closely related questions about differential correction with a Garmin unit: 1). Some data was collected using a Garmin GPSMAP 76Cx unit and the data collectors are interested in whether post-...
5
votes
3answers
2k views

GPS Datalogger with USB Interface and GPX Output

I'm looking for a reliable, robust and reasonably priced GPS datalogger, to measure time, distance on tracks. The logger should be reasonably priced but ready for outdoor activities. Mud, dirt, a ...
5
votes
3answers
3k views

GPS post processing - Differential Correction

I have a large set of collected GPS points that I'm pulling into Arcgis from SQL and creating an xy event layer to then map them. The fields for the points are as follows: recorded, lat, long, ...
5
votes
1answer
6k views

How can I convert Horizontal dilution of position to a radius of 68% confidence?

I am working at mobile app that uses external GPS module. What I need is to calculate accuracy for the fix from GPGGA command to be able to compare it with my mobile platform's GPS accuracy. Mobile ...
5
votes
1answer
471 views

Why are points collected with a Trimble FM 750 off by more than a mile when displayed in QGIS?

I have a grower that has a FM 750 and is trying to make points in a field. When finished he takes the file out of the display and goes to his computer and he can bring up the points in the right ...
5
votes
1answer
500 views

PLT track in PostGIS

What are the best practices for importing and aggregating tracks (in my case in 'plt' format) in a PostGIS table, grouped by user. Are there any tools/db models/tutorials available?
5
votes
2answers
2k views

Does iOS know the phone's location solely from cell tower, i.e. without GPS data?

Question Does the iOS operating system know the phone's location even if one could turn off the iPhone's built-in GPS module or if it was broken? Elaboration What I understand I understand that ...
5
votes
1answer
548 views

If the GPS navigation message takes 12 1/2 minutes to cycle, how can receivers update your position every second?

According to Wikipedia's article on GPS, Each GPS satellite continuously broadcasts a navigation message... Each complete message takes 750 seconds (12 1/2 minutes) to complete. My ...
5
votes
2answers
5k views

How to merge multiple file geodatabases into one file geodatabase?

I have created a file geodatabase that has several feature data sets, feature classes, and domains. I have created a map with the file geodatabase added to it, converted the map to ARCPAD AXF format ...
5
votes
1answer
549 views

How to connect particular sets of points with (poly)lines?

I think my problem is quite easy to be solved by the most postgis-users, but i am a bloody beginner: i have a timestamped point-table representing GPS-tracked places of different cars. To distinguish ...
5
votes
2answers
1k views

Garmin etrex 10 and QGIS

I want to know if anyone has been able to download data from a etrex 10/20/30 directly from Qgis. The usb protocol decsribe in a recent post does not do the trick. GpsBabel documentation states that ...
5
votes
1answer
145 views

How does a GPS unit ensure it has the same time reference as a GPS satellite?

I've been reading about GPS to find how it works, but one thing still bothers me. To calculate distance from GPS unit/receiver to GPS satellite, it uses the difference between radio signal sending ...
5
votes
3answers
248 views

Mapping Trails with GPS - Hardware Suggestions

I have been hired to map about 100km of XC ski trails. I am super proficient in GIS but have not done any detailed GPS work since college when I worked with some sort of Trimble explorers. This is a ...
5
votes
1answer
516 views

Sub-meter Bluetooth GPS units and ESRI Collector App

We have been using Trimble XT/XH for years now, but we are at a time when we need to upgrade and do not want to drop another $8000 for another Trimble that only causes us headaches and not very user ...
5
votes
0answers
339 views

GPS data based track/trip calculation algorithm available?

Currently I'm receiving position data of moving assets every 90 or 120 seconds (depending on the asset). What I'd like to achieve now is to detect standstill and movement phases (tracks/trips) on the ...
4
votes
3answers
5k views

Measuring polyline using either QGIS or ArcGIS Desktop?

I've collected a bunch of GPS polylines (WGS84). What is the easiest way to measure the length of these lines in KM using QGIS or ArcGIS Desktop?
4
votes
3answers
303 views

Differentiating a building from a road on a map?

This question was originally asked here by Steven and I felt the question was better asked here. Steven would also like to know the sources Google buys it maps from. I remember seeing a post about it ...
4
votes
5answers
459 views

How do I find software for my GPS?

I recently unearthed a GPS unit I purchased a few years. It's a Garmin GPSmap 60 (picture) and has a usb port on it. Is there a way that I can link it to my mac? I do have windows installed also, and ...
4
votes
3answers
2k 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) -...
4
votes
3answers
102 views

What view of sky is required for RTK GPS

When using RTK or differential GPS technologies, considering the Base has a clear unobstructed view, what view of the sky is required to be able to get an accurate fix with the rover when is moving (...
4
votes
4answers
5k views

Connecting GPS to ArcGIS via USB

Is there a way to connect a GPS to ArcGIS via USB? At the moment the GPS extension only appears to support comm port connections. It would be good to know if a USB connection can be made, then perhaps ...
4
votes
2answers
197 views

Road segments reconstruction from GPS trajectories

We have a 10,000 base of vehicle mounted moving devices which report their GPS position on a time based schedule. All that data is currently being stored in our database for several business related ...
4
votes
2answers
218 views

Calculating new satellite position given pseudorange measurements

I'm looking for a reference/text for an explicit formula to calculate a satellite position given pseudorange measurements from later epoch times. I've seen a lot of matlab code on the internet but I ...
4
votes
1answer
197 views

Extract one GPS fix per day from data?

I am in the fortunate position of having 2 years worth of animal movement data. With such a large amount of data I would like to extract only one fix per day to make it easier to work with. Data = 14 ...
4
votes
4answers
1k views

Android devices and apps with support for Galileo positioning

While the European's Galileo positioning system is only expected to be fully deployed by 2020, the first positioning made using already deployed Galileo satellites was made back in 2013. Also, ...
4
votes
3answers
152 views

How to evaluate performance of GPS/GNSS unit

I need to integrate some sort of satellite-based positioning for a mobile robot project. I am at the very beginning - I got 2 u-blox GNSS evaluation boards (these NEO-M8Ts) - I chose an integrated ...
4
votes
1answer
300 views

Calculating speed along point feature class (.gpx) in ArcMap?

I have imported a .gpx file into ArcMap as a point feature class. Each feature has a Point z as well as a DateTime. I want to create a graph that shows speed as a function of distance. How do I do ...
4
votes
1answer
13k views

Looking for an android solution for offline kml/kmz file viewer with gps support

I have some KMZ files of cadastral maps. I need to fiscally go to the boundaries of my lands (parcels) and take a look at where they are with the gps and maps support. Some of these places are not ...
4
votes
3answers
237 views

Is there a service to check whether a gps path belongs to a public road?

I have a bunch of GPS tracks. I want to exclude the ones which go via public roads. I'm interested in off-road segments only. Is there any public api to check if a given set of coordinates belongs to ...
4
votes
3answers
632 views

Wildlife surveys using tablet and GPS, import/export to/from ArcMap

I've found some info about this on a previous post (Advanced android app for mapping and GPS logging), but it didn't provide enough info, I'm hoping some other tech experts can help! I have a tablet (...
4
votes
1answer
5k views

Distance calculation : Integrating incremental gps data

I am trying to build a GPS based odometer based on android. Currently , I am calculating incremental distance changes very frequently ( < 5 meter movement). The distance calculation in android is ...
4
votes
3answers
681 views

API to suggest nearby streets

For an app I'm developing, I want to use the phone's GPS to locate it. I then want it to list streets that are nearby. The customer might be in his back garden for example, and this may be closer to ...
4
votes
1answer
2k views

How to read multiple .gpx files in R [closed]

Suppose I have a number of .gpx files (these contain GPX waypoint data from a Garmin eTrex). I want to load them into R with different names and manipulate them. I can read one file thus: library(...
4
votes
1answer
584 views

how to create a network from gps tracks?

I'm trying to build a network from several GPS-trakcs, to digitalize hiking routes on my land. I have several GPX-files from routes I've tracked with the gps. I managed to display them in Arcmap 10....
4
votes
1answer
6k views

How to calculate Bearing between two GPS points

The following returns 150 degrees using C# converted from JavaScript Bearing formulas, but Google earth returns 210 degrees for the same values. The broken code is GetBearing() but I've also included ...
4
votes
1answer
475 views

RINEX specs and OS library

Is there any OS library to read/write/process RINEX data? I've been wanting to start a OS library to read and write RINEX, which is something I need for a project, but not actually post-process them. ...
4
votes
2answers
2k views

Point interpolation in route

I have a set of GPS coords with X,Y and Course. I need to interpolate additional points based on the course of each point. It would be a simple line intersection based on lines drawn using the 2 ...