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July 11, 2010
News - High Altitude Balloon Pro…
about 5 years ago
Regading spin stablization; this is outside my area of knowledge but I wonder if some vertical ‘fins’ along each side if the payload would help. Yes, this would make it more vulnerable to wind but is that really a problem?
Tutorial - HAB - Sensor System, Flight Computer, and Radio System
about 5 years ago
I’d have two radios in the unit; the first being the microwave high-bandwidth one described above, and the second being an HF beacon for a locator, which would do something like transmit a different digit of its lat/long every 5 minutes or so. I’d use an omnidirectional antenna here, vertically polarized. You could also use an APRS locator but I am not sure how well APRS stuff works when you have a need for great distance and low power consumption.
Directly soldering, instead of using connectors, will increase reliablity. Failing that, use good quality brass connectors.
The problem with using off-the-shelf, part-15 hardware is that everyone else is ising it too. You need to some quiet radio spectrum. This is where ham radio comes in handy; there’s lots of spectrum in the microwave region which is fairly quiet. You could transmit real-time video here and not crowd other signals out. At higher bandwidths, of course, antennas are smaller. I’ve thought of using a yagi, with element spacing accomplished by weight on a line from the balloon, but then the elements themselves might not be stable. You might want to try a circularly polarized yagi, with circular elements so the polarization problem is eliminated, but then there’s some weight being added. But it may not be worth worrying at all, if you’re at 10 ghz the directional antennas you can use can be very small, and don’t have to be the string-supported yagis I describe.
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