Late Saturday evening on January 13th, SSI conducted a long-range test of its SRADio (Student Researched And Designed Radio) system. One team drove to a vista point on Skyline Boulevard, while another team went to the Stanford Radio Shack, which is positioned along The Dish trail. The Skyline team transmitted packets while the Stanford team received them. Under various settings, the number of packets dropped out of a benchmark of 20 was counted.
The radio system performed well at an effective distance of 31 kilometers at a data transmission rate of 5 and 50 kilobits per second, which proved it successful for the applications it is designed for.
IMG_2814.JPG 1.52 MB
IMG_2814.JPG 1.52 MB
The SRADio system was built by Sasha Maldonado, Sharon Platt, Aria Tedjarati, Joan Creus-Costa, and Tim Vrakas. The system will be used by the IREC team to downlink live telemetry from the rocket. It will also be used by the ValBal and Buzz projects to set up a continental US-wide high altitude balloon communication network.
To simulate the environment of a rocket, the Skyline team placed the transmitter inside a rocket airframe. The carbon fiber of the rocket’s airframe can affect radio wave propagation because it is conductive. While the team was planning on building a carbon fiber rocket at the time of the test, the team has since decided to switch entirely to fiberglass.
The large distance between the two points, which is about ten kilometers, ensured that the radio would function at great distances. A shorter range test can be conducted with attenuation in place of a long range test, however there is the risk that the signal bypasses the attenuation by being transmitted or picked up by the traces on the transmitter or receiver board. As a result, short range tests are not always reliable indicators of whether or not a system will function at great distance.
Halfway through the test drag racers showed up at the vista point parking lot the Skyline team was positioned at. The San Mateo Police Department and California Highway Patrol swiftly arrived to stop the dangerous activity, and permitted the Skyline team to finish the test. We would like to thank the San Mateo Police Department and California Highway Patrol for their support during the test. Without them the test could not have been fully completed.