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Post by tracyk on Aug 10, 2016 8:45:23 GMT -7
We are wanting to do our first tethered flight on 8/21/16 to test the modems for both the BCTC and UK teams. Having never conducted one of these tethered flights before I was wondering if we can use a smaller balloon to save money on helium (currently have 1600g). Any suggestions on optimum size balloon for tethered flight to use a maximum of one helium tank? Also is there a minimum height above the ground that we need to reach for the modem to communicate optimally? Thanks!
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Post by Skylar MSGC on Aug 18, 2016 11:47:55 GMT -7
So I haven't done too much with picking the balloons but Berk Knighton (MSGC flight advisor) would be the person to ask about that.
With the connection between modems, You should be able to flight at any level and have decent connection, the only thing you might need to worry about is interference from other devices. Cellphone frequency (4G) for Sprint is 2.5GHz-2.7GHz, So most likely you won't have interference from that considering the second harmonics for those frequencies are (respectively) 5.0GHz-5.4GHz. [First and second harmonics of frequency is where most of the power for the transmission is]. The rest of the cellphone companies are at lower frequency.
These Ubiquiti modems were originally created for providing WiFi to a whole city block at once. We have re-purposed them to a long range setup using the dish to focus the transmission power instead of just projecting in every direction at once.
So you still may run into interference between devices in the payload. I would not recommend flying the Ubiquiti modems and Iridium modem in the same payload. We have found that the Ubiquiti modems will drown out the Iridium modem and no GPS/Iridium connection would be established.
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Post by ProfLeeT on Sept 16, 2016 13:56:01 GMT -7
We would also like to do a tethered flight since redesigning our video payload to include a GPS tracker. We were wondering if it is possible to reuse a balloon if we can pull it down and ensure it doesn't touch anything other than gloved hands?
Or would it be better (to not waste Helium and potentially a balloon) to find a way to move our ground station to a ground-based location at a much higher altitude?
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