Because our autonomous balloon is so high, and has a great antenna, it can repeat or re-transmit any voice communications from the ground. This means that an ambulance or fire truck can talk to headquarters on their little mobile radio, even if they are 100 miles away. That is the subject of the previous post.
Another cool thing that our balloon can do is to provide APRS "hops". APRS radios like ours transmit their GPS coordinates on a regular interval. When a special ground station called an i-gate hears this message, it can put the information on the internet so anyone can see that unit's location. The problem is that if the APRS radio is not near to an i-gate, then no-one knows where it is. Our balloon, though, because of its altitude and antenna, can hear any APRS transmission within about 100 miles. (During our second flight, our longest range transmission was over 130 miles). Not only can the balloon hear it, it can re-transmit it to an i-gate. This is called an APRS "hop". So if the commander at the HQ wants to know at any time where all the rescue teams are, instead of talking to everyone, he or she could just look at a live moving map with all the units displayed. To cover a large area like the island of Puerto Rico, we could launch several balloons that would talk with each other and cover the whole island. Our blog includes more details on APRS and how we built our radio using inexpensive parts. The TNC in our system can be easily configured to provide hops.
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Recent events have highlighted reasons for us to use our autonomous balloon technology for humanitarian purposes.
Here is the way we could use our balloon; in a crisis, we could repeat radio transmissions or make cell coverage when cell phone towers are knocked out. Here are examples of what we mean: Puerto Rico has seen widespread hurricane damage and flooding, and not a single person can communicate whatsoever so coordination is rough. What we could do is send our balloon up with our radio, which can repeat any messages within 100 miles! How do we repeat to a 100 mile radius? Our inexpensive 2 meter hand-talkie radio only transmits at 4 watts, but with our good homemade antenna and lots of altitude, we can communicate with stations very far away. The higher it is, the better the coverage. When we were testing our radio on the ground, we had to be less than a mile away from a ground station to make contact. This is the situation in Puerto Rico... Emergency services cannot talk to each other. Once our balloon was above 2500 feet, our same little radio was talking to stations more than 130 miles away! So in a humanitarian crisis, if we launch our balloon to altitude, then a ground radio can communicate to the balloon because there is direct line of sight. Then our balloon repeats the message to other ground stations. This means that two ground stations can talk to each other over massive distances. Texas had another hurricane attack, and coordinating and communication were also problems, but not as bad because their cell towers survived. This is an example of how things can work better when people can talk to each other. Of course there a many more examples, but I think you get the picture. What would be even better than Emergency services talking on the radio is if we could restore cell phone service. What we do, is we send a $250 balloon into the air with a cell repeater, and it acts as a cell phone tower. Now, people who are trapped can call for help. |
AuthorMalachi and Ezra's page where we build cool stuff and either break it, set fire to it, etc. in the name of science. Archives
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