Lit Review

Follow this link to read the description of the Lit Review assignment (you can also find the link on the Course syllabus page:

Project Description

Folow this link to read through an example template for the class project (there is also a link on the course syllabus page):

Raster Layers Review

The lab this week is working with Raster data. Have a look through the lecture from Friday to get a better understanding of this data type.

Global Navigation Satellite System (GNSS)

GPS – What we really mean is GNSS – Global Navigation Satellite System. GPS is actually a subset of GNSS, below is a list of some of the satellite networks covered under the GNSS unbrella

GPS: Global Positioning System – USA
GLONASS: Globalnaya Navigazionnaya Sputnikovaya Sistema, or Global Navigation Satellite System – It has Sputnik in the name – must be Russian
BeiDou: Navigation Satellite System (BDS) – Chinese
Galileo: European Union
Quasi-Zenith Satellite System (QZSS): Japan
NAVICIndian Regional Navigation Satellite System (IRNSS) : India

The always useful Wikipedia link

Using a GNSS receiver (i.e. your phone)

You GNSS unit (OK we still call them GPS units) needs a few things to start collecting location information. Fist, your guessed it, it needs to be able to collect information from satellites.

Check out the animation from the US Department of Transportation

Here is another diagram from illustrating the need at least for four satellites to get proper location information. Click on the image to read the page describing the collection method :

GNSS is really using a method called Trilateration (Wikipedia) where a object is located by using other moving objects whereby the moving objects have know locations at known times. Or – it just works!

Almanacs and Ephemeris information

When a GNSS receiver is started, it looks to build location information from the radio signals it is receiving from the orbiting satellites.

It first uses Almanac information. This information is a rough estimate of satellite locations in a constellation and is sent by all satellites in the constellation. This a rough estimate, but it helps the receiver build an initial location model.

The Ephemeris information is sent by each satellite and has precise information for the satellite sending the ephemeris data. Once there are four satellites being tracked using the ephemeris data, the receiver can start collecting location information:

Augmented or Assisted GPS/GNSS – your mobile phone

Our receivers and antennas on cell phones are not very powerful (excepts Scott’s old Nokia) as they will drain batteries.  There is a mechanism to get supplementary location data (such as the almanac and ephemeris data) from using your cell network – A-GPS.  Again we will look at the Wikipedia page for help.

Start collecting data for next week’s lab and tutorials

Start using the apps recommended to gather both tracks and waypoint information.

OpenGPX Tracker – iPhone
GPS Logger – Android

Once you get some information, we will upload the tracks and waypoints to osmotar in our labs next week.