Hexagon | NovAtel engineer Rob Watson found himself in a familiar situation to many parents working from home. While balancing work and ensuring his children were both learning and entertained, he thought of a way to bring the two together by teaching his children how satellite navigation works in a hands-on way.
Satellite Navigation in a Science-Art Project
With two school-aged children at home since mid-March, I spend a lot of time asking myself, “How can I keep them learning today?” Bridging my work in GNSS and my children’s education, I decided to use strings and pins to explain GPS in a fun and interactive way.
First, the plan was to use nails on a board and get my kids to measure points with a string. But then things spiraled out of control, as many things do, and the plan evolved into a functional art project. The real challenge: what could we build using materials we already had in the house?
Step 1: Building the Satellites
We needed to build satellites with antennas.
Using some brass rod leftover from fixing my fridge, and three-millimeter thick fiberboard we still had from building cabinet doors, we created these satellites:
Which, of course, needed to be painted:
Step 2: Creating the Earth
With a remaining, larger piece of fiberboard, we created the backdrop.
The challenge here was to have enough of Earth shown for us to determine positioning, but also to have a reasonable amount of space shown for satellites.
Using a string and a pencil, we plotted a curve to outline the Earth:
From there, we needed to include land and water. I browsed Google Earth and found this perspective view on Europe – it was an excellent match for the fiberboard space.
I drew some latitude and longitude lines and started drawing the coastline by hand. The resulting coasts aren’t one hundred percent accurate, but artistic freedom is necessary now and then:
After painting, we have our final model of space, Earth, white dots representing cities, and a small constellation of satellites:
Step 3: Calculating Pseudoranges
We attached string to our satellites to replicate their ranges. I tied knots every 10 centimeters on the string so we would have units to measure distance by; this is how we calculated pseudoranges (the estimated distances between satellites and equipment receivers). This is how I introduced satellite navigation.
Learning Satellite Navigation and Positioning Hands-On
I painted white spots across the Earth to represent different cities so the kids could calculate their positions and learn a bit of geography in the process. To make the project a bit more challenging for them, I measured sets of pseudoranges to different cities and captured them in a table. With the table and the strings, I asked the kids to find which city was in which location.
While this science and art project only scratches the surface of how satellite navigation and positioning works, it was a great introduction to basic GNSS concepts. From this introduction, I was able to begin explaining more in-depth principles, like the geometry of positioning and needing at least three satellites for unambiguous 2D positioning. We could easily visualize precise positioning by using larger or smaller knots. Errors in measurements were demonstrated with poorly placed knots or by using strings with more elasticity.
This science/art project was a fun activity with my kids while I’m working from home, and they enjoyed learning at least the basics behind what I do every day.