Since getting back from New Zealand, the Project Loon team has been busy conducting a series of research flights in California’s Central Valley. The purpose of these flights is to allow us to research various approaches for improving the technology, like the power systems (solar panel orientation and batteries), envelope design, and radio configuration. We’ll be doing a series of posts on what we learn from these flights, and how the technology develops as a result.

On our most recent research flight we overflew Fresno, a nearby city, to get statistics on how the presence of lots of other radio signals (signal-noise) in cities affects our ability to transmit Internet. It turns out that providing Internet access to a busy city is hard because there are already many other radio signals around, and the balloons’ antennas pick up a lot of that extra noise. This increases the error-rate in decoding the Loon signal, so the signal has to be transmitted multiple times, decreasing the effective bandwidth.

This is like trying to talk to a friend at a loud concert. The the music interferes with your voice, so your friend might have to ask you to repeat what you said a few times in order to make sure she heard it correctly. This will result in a more basic conversation; instead of speaking about complicated topics in depth, you’ll have to spend a lot of your time repeating yourself just to make sure your friend can understand you!

One way to deal with this is to speak louder, or in the case of a Loon balloon, to increase the signal strength. Our tests over Fresno will help us understand how signal-noise interferes with our signals, so we can determine how strong we’ll need to make our signal in order to transmit it effectively. 
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Central Valley Research Flights
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