Objectives:

To learn the basics of GPS signal reception and the calculation of position from pseudoranges.

Requirements:

In this assignment, you and your partners will record some GNSS data, send it to a computer, and analyse what you see. The data you produce will be a log showing you walking a route that spells the first letter of your name, and you share your data with your partners. The assignment has some basic requirements. The extra, “bonus” requirements are not required in order to pass the assignment, but will result in higher marks being awarded.

Minimum requirements:

•    Import: previously, there have been some issues with which version of the

software runs under which version of Android and related issues. Please get onto this early and share on the forum which version worked for you and any modifications you needed to make in order to get it working.

•    If you have an Android device, check here to see if it logs GNSS data. If so,

download and install “GNSSLogger” from the Android App Store or here using your Android device. If you do not have an appropriate Android device, use a friend’s – you will need to create data that is unique to you, so don’t just use someone else’s data.

•     Go to a location where you can walk freely, such as a park or oval. Plan where you are going to walk in order to make a track that shows the first letter of  your name.

•    Run GnssLogger under Android. On the settings tab, turn on “Location”,

“Measurements”, “Navigation Message”, “GnssStatus”, “NMEA”,

“Autoscroll”. Then choose the log tab and press “START LOG” . Now walk the route that you planned, so that the track is in the shape of the first letter of your name. Then press “STOP AND SEND”. You are presented with a number of ways (e.g. email) to transmit the data. Choose whichever is best for you and send it to your computer for analysis.

•    Install the GNSS Analysis app using the instructions here onto your computer. Run the program as required by your sort of computer. Press “Find Log File” and navigate to where you stored the log. Then press “Analyse and Plot” . Several windows will appear with plots showing various elements of receiver performance. You are now ready to do the analysis required from the assignment.

•     Share your log with your partners and be prepared to process their data as well.

•    Questions:

1.   What GNSS systems can your device receive? What about your

partners? In your data log, does it show them all being received? In the analysis plots does it show them all being received? Explain.

2.   The first plot of the GNSS Analysis Tools is the top four satellites in order of received power for each system – green being “good” . Do the results for those satellites make sense, i.e. is the strongest signal the one you would expect to be strongest etc? Which other plots did you use to back up your answer?

3.   Have a look at the plot of pseudorange over time (it should be the

second left at the top). Is there a common trend in this graph? Can you use one of the other plots to explain that trend?

4.   Did the plot of your name’s initial letter work out so you can tell what letter it is? What is the problem? How could you have made it better?

5.   You and your partners will have different data from different locations recorded on different devices. Answer all of the above questions and try to explain why the results are different (or the same?) for each log from the different partners.

Bonus requirements:

•    Questions:

1.   Are you able to plot your positions on a map or satellite imagery?

2.   Can you edit the data file so that there is only GPS data, only Glonass etc? How do the results compare between systems, and with the combined solution?

3.   If necessary, act on your advice above to plot a better version of your name’s initial letter.

Your answers must be written up in a technical report according to the report template in Moodle. If you had difficulties or made discoveries about how better to run the software, include these in your background section, as part of the experiment description. A typical report will be about 10 pages long.

Assessment:

Report: 100% of total mark. Guidelines for report writing and a report marking scheme are on the course website. Penalty (i.e. negative) marks can be assigned so make sure you familiarise yourself with what is required.