Space-Constrained Fit

The clocks on board the satellite will drift somewhat over an extended period of time. The precise time available from the NovAtel receiver will be used to correct for this drift for accurate scientific monitoring.

Charles Nokes, Project Manager of Ex-Alta 1 project at the University of Alberta, explains, “Members of our team contacted NovAtel early in the design process. The company executives were excited to participate in the project and immediately sent two OEM615™ units to use so that we had one to fly and one to test. It is really great the way NovAtel worked with us. This is a student volunteer project, not an official academic program; it’s something that students work on in their spare time. Our partnership with NovAtel has been great. Having a company like NovAtel’s support helped make this project possible.”

The OEM615 Global Navigation Satellite System (GNSS) positioning system is able to track GPS, GLONASS, Galileo and BeiDou. It’s easy to integrate, has low power consumption (1 W), is lightweight (24 g) and is small in size (71 mm x 46 mm x 11 mm).

The positioning system is located on the anti-ram side, the side that points opposite the direction of the Ex-Alta 1 satellite’s motion. (Note: the ram side of the satellite faces in the direction of the satellite’s motion.)

Nokes continues, “Integrating the GPS and the antenna was an interesting process because we needed to have access to GPS signals to test the connection to the antenna and its functionality. We did not have access to a GPS simulator, so we ended up testing the GPS in real-time on the roof.”

The team designed a sealed portable container that could transport the satellite and facilitate the interface. Once on the roof, the GPS antenna on the satellite acquired signals from GPS satellites overhead. They initialized the OEM615 unit and verified that the spacecraft could obtain a lock on the location and the time. Once launched into the ionosphere, the student-led team sent commands to turn on the GPS in orbit. The environment on orbit in the ionosphere has much higher levels of radiation. The GPS unit may be affected by interactions with large numbers of high energy particles.