Tagged Questions

GPS is a space-based satellite navigation system that provides location and time information.

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1
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0answers
256 views

how to correct the coordinate of points [closed]

I have some a layer which contains some points. The coordinate of the points should be GPS points. However, the coordinate of these points are not correct. What should I do? I am using QGIS. If I ...
3
votes
2answers
190 views

What is the minimal data necessary to reconstruct GPS location?

Imagine that a minimal GPS device is attached to a moving object (animal, shipping container, geocache object, etc). Every few months, data from the device is downloaded for post-processing. What ...
3
votes
1answer
172 views

is the GPS network free or available for any device?

I have a question (I'm really sorry if is kind of dumb question). But if I have a device with GPS (smarthphone,pda,pocket pc, etc) Does the device need any additional service to enable GPS data? I ...
3
votes
6answers
7k views

Sending GPS Location to server

Is it possible to send my current location on iPhone or Android to the server so that others can view my current location?
5
votes
2answers
837 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 ...
2
votes
1answer
501 views

Snap Polygon vertices to Point features

I have a set of polygons drawn using an inaccurate GPS PDA. these polygons are sharing nodes. after post-processing GPS data to get accurate coordinates i have a set of all the nodes, then i have to ...
11
votes
1answer
637 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 ...
1
vote
3answers
240 views

How to upload and download to gps

Do you have a step by step guide on how to upload/download points/wayponts and polylines/routes from a gps? Regards Christo
3
votes
1answer
217 views

How to overlay map onto a corner of an image, using that image's GPS exif data?

I have several hundred JPG images taken during a time lapse of a drive, with each image containing embedded GPS information. Is there an OS X friendly workflow that can allow me to: create a ...
13
votes
3answers
4k views

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 ...
3
votes
1answer
367 views

GPS problem in QGIS

I have a very strange problem that I cannot understand. I am trying to put together a demo-laptop with QGIS and gps. On other computers I have it working as expected, but on this particular box ...
19
votes
2answers
419 views

Precision when working with spatial data in GIS

Is there a basic or introductory study that examines and compares the precision of spatial data when working with varying precison of the data input, like having 1, 2, ... decimal places? with the ...
2
votes
1answer
2k views

How do I calculate a xyz-position of a gps-position relative to an other gps-position?

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? Thanks in advance. Edit: The locations have a ...
10
votes
3answers
2k views

Bluetooth GPS to Smart Phone

Has anyone had any luck intergrating a GPS unit with your Smartphone? Looking to gain sub 5m accuracy. Ideally would like the phone to just use the better gps reciever when it is connected. This ...
4
votes
1answer
257 views

Proper work flow to move manholes and pipes to surveyed location

I would like to know how to accomplish the following task using QGIS. I have an existing point shapefile representing sanitary sewer manholes and an existing polyline shapefile representing sanitary ...
1
vote
1answer
160 views

Mobile location determination

I was wondering how Google Maps on my Android phone can locate me with a good accuracy when my GPS is disabled. At first I though it was with the cell tower but I'm not sure it can achieve this ...
22
votes
7answers
7k 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 ...
2
votes
2answers
558 views

How to convert Garmin Waypoints to Google Mercator?

I have georef some topocards with QGIS and the Google Hybrid Layer. So, this cards are connected with the Google Mercator System. Now I have some waypoints taken with Garmin GPSmap62 (in WGS84). ...
1
vote
0answers
310 views

Holux GPS logger .itm fileformat

I'm looking for a spec sheet or a library to open and decompress .itm files from the Holux GPS logger. Has anyone worked with the proprietary .itm format already and can provide me with some usefull ...
3
votes
2answers
409 views

How to get the layers of my project to show while tracking with GPS?

I've been using/testing several versions of various GIS software and run into occasional issues. Right now, my biggest with QGIS is with GPS connection/downloading from/tracking. These are all ...
32
votes
12answers
22k 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 ...
11
votes
2answers
1k views

Why is getting a 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 ...
3
votes
3answers
848 views

GPS device taking pictures and saving heading + HDOP?

I'm looking for a device that can do all of the following: Take picture Save lat-long GPS position + heading (angle to North) of picture [so need tilt-compensated 3D compass], in exif or other ...
0
votes
0answers
37 views

Calculating ECEF X, Y, and Z velocities between 2 points on Earth [duplicate]

Possible Duplicate: How do I calculate ECEF X,Y,Z velocities for GPS if I have no satellites This is my third attempt at explaining what I'm trying to do. If I have two ECEF X, Y, Z ...
1
vote
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 ...
0
votes
0answers
52 views

Calculate XYZ velocities between 2 ECEF points [duplicate]

Possible Duplicate: How do I calculate ECEF X,Y,Z velocities for GPS if I have no satellites If I have a starting location (Latitude/Longitude), a bearing (degrees), and a speed (m/s), how ...
3
votes
3answers
5k 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 ...
7
votes
1answer
206 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, ...
1
vote
1answer
472 views

Sensitivity of Garmin eTrex 30

I have a very good experience with Garmin eTrex Legend HCx - here and here they write that HCx has a very sensitive chip, that works in forest, deep valleys and in cities - and I can only confirm - ...
3
votes
1answer
3k views

Difference between Garmin eTrex Legend HCx and eTrex 30?

I have used etrex Legend HCx a lot and been satisfied. Now I've seen etrex 30 just for a while and it seems to me that the Legend is much more user friendly, good old menus with a lot of ...
3
votes
2answers
399 views

Classification of GPS trajectory

I need a detailed description of a GPS trajectories. I don't need to know what a GPS trajectory is, I already know it. Exactly I need a paper (better if scientific cut) that talk about different type ...
12
votes
3answers
852 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 ...
5
votes
2answers
2k 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 ...
2
votes
0answers
125 views

How to configure various client applications to display AVL data?

Given x number of GPS units transmitting NMEA formatted strings back to a server (xxx.xxx.xxx.xxx:xxxxx) is there a way to listen in on the traffic and parse NMEA formatted strings for display on a ...
10
votes
1answer
542 views

Overview of GPS tracking system technologies

Background: I've been asked by a friend to estimate the cost of setting up a GPS tracking system for a small fleet of buses, so we can do real time reporting of bus locations via a webmap. In my ...
4
votes
4answers
3k 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 ...
5
votes
1answer
314 views

Differentially correct GPX file

Is there any way to differentially correct a GPX file using free or open-source tools? Does a GPX file contain the necessary information for differential correction (I can put the timestamp in it ...
1
vote
1answer
2k views

Go to X,Y dialog box

If someone gave you a x,y coordinate numbers he/she got from. I put the numbers in the X,Y events on my ArcMap and they are in Meters numbers. We entered the number into the x,y dialog box. The ...
4
votes
2answers
2k views

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 ...
7
votes
2answers
2k 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 ...
0
votes
1answer
308 views

What GPS unit can I use to track myself all day for a 10 day trip? [duplicate]

Possible Duplicate: Logging GPS and Accelerometer Data - Device Suggestion? I will be visiting China this October as part of a field studies course and I want to be able to take the ...
1
vote
2answers
257 views

Is there a time limit on post-processing GPS data with Pathfinder Office?

Do I need to post process my GPS data within a certain amount of time after collection? Do the services that provide the correction data to Pathfinder Office only make that data available for a ...
4
votes
3answers
2k 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, ...
3
votes
3answers
876 views

GPS drift during the receiver is stationed

I have developed a GPS Tracking device it is working fine when the receiver is in motion, when it stationed in a position for couple of hours i get some drift for around 10-15meters. The receiver send ...
2
votes
1answer
1k views

how to calculate RMS 2D and RMS 1D, using python?

I would like to calculate: RMS 2D: standard deviation for the two coordinates of flat (67% confidence level) and RMS 1D: standard deviation for height (67% confidence level) What is the formula and ...
5
votes
1answer
7k views

How to batch convert Garmin GDB to GPX?

I need to convert a lot of garmin GDB files to GPX in order to convert it to another vector format. Is there any tools available can do a batch convert from garmin GDB files to GPX? Using MapSource ...
0
votes
1answer
111 views

Programs to log NMEA on Nomad 900?

I am interested in logging NMEA data on a Trimble Nomad 900. Unfortunately the SatViewer records a maximum of 64,000 characters, too little for my application. I don't want to have to purchase ...
8
votes
0answers
304 views

Is there open source GPS post-processing software? [duplicate]

Possible Duplicate: Post Processing GPS Data with open source software Here at the office we have a couple of 15-year-old Trimble 4700 and 4800 units but now we don't have the software to ...
21
votes
4answers
8k views

Why is GPS a free service?

The Global Positioning System (GPS) is a free service that is owned and operated by the U.S. Government and is always available. When we buy a GPS device, we don't pay a monthly fee or pay a tax for ...
16
votes
2answers
12k views

What is the difference between triangulation and trilateration?

Looking around I noticed that many people exchange the terms (tringlulation and trilateration) for the same sense. What's, actually, the correct sense of Triangulation and what are the differences ...