Satellites Blog

Satellites Team Talks Over Ten Kilometers!

After nearly two years of effort and a summer of hard work, the SSI satellites team has achieved our goal of a 10km optical communications link! On the night of August 20th, 2016 we successfully established a two-way optical communications link between the Stanford Amateur Radio Facility and the Skyline Boulevard Overlook. This was the first time our custom built transmitter and receiver boxes have both sent and received data over such a large distance!

After aligning the sensors using a motorized telescope mount, the laser (a standard low power laser pointer) was visible to the naked eye as a gentle flickering red light in the distance. The terrestrial link sent text messages through the atmosphere. The hazy conditions periodically occluded the laser, but we were able to transmit through periodic “windows” of clear air. Under the best of conditions our current communications rig is capable of transmitting and receiving at 10kb/sec, which is primarily limited by the sampling rate of the team’s Teensy Microcontroller. This 10km test is an exciting distance because at sea level the laser will pass through the same number of molecules of atmosphere as it would from a ground station to one in low earth orbit.

The success of this long distance test is an important step towards our goal of building an optical communications system in space. Over the next year the team will be working hard to realize a bi-directional optical communications satellite. We are looking forward to the year to come!

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