Server in the clouds: Project summary

Friends, it's time to sum up our project-competition "Server in the clouds". If someone does not know, we have zapilili fanic gik-project: they made a small server on Raspberry Pi ? screwed to it a GPS tracker and sensors, loaded all this stuff into a balloon and trusted the forces of nature. Where the ball lands, it is known only to the gods of the winds and the patrons of aeronautics, so we invited everyone to put the points on the map - whose points will be closest to the actual landing site, receive "tasty" prizes.
Server in the clouds: Project summary
So, our server has already flown to the clouds, and it's time to sum up our competition.

References to previous publications about the contest [/b]
Post about regatta (the prize for the first place in our competition is participation in the sailing regatta AFR (Another F * cking Race) , which will be held from 3 to 10 November in the Saronic Gulf (Greece) in conjunction with the team RUVDS and Khabra
How did we do " iron part "Project - for fans of geek-porn, with details and analysis of the code.
Megapost about the project with a full description.
The project site is , which could monitor the movement of the ball and telemetry in real time.
Reporting from the launch site of the ball.

And experience, the son of the mistakes of difficult

As you remember, we planned to broadcast data from the server via GSM-modem. This was the main channel for information transfer. We thought we had provided for any surprises with the coverage of the cellular network by inserting into the modem two SIM-cards of the operators with the best coverage in the Dmitrovsky district. In addition, the modem had a good omni-directional antenna. But, as they say, a person presumes, but puts pressure on the opossians. When the balloon rose above 500 meters (the height of the Ostankino TV tower), the cellular communication disappeared completely.
Thinking backwards, it seems obvious, but then it's the back number. Of course, cellular antennas are designed to cover on the ground, and not in the air. Their directional patterns "beat" along the relief and do not "shine" in the clouds. So cellular communication at a height of half a kilometer and above is only a random re-reflection of the petal of some antenna. So half of the route of communication with the ball on the cellular channel was not. And on the decline, when they descended below 500 meters, the cellular communication again earned.
How did we receive telemetry from the balloon? For this, thanks to the duplicate data channel. We installed a set on the ball. LoRa-radio communication , operating at a frequency of 433 MHz.
The capacity is not large, but for our problems it was quite enough. As for determining the location of the ball on the GPS, then there was no problem with it, the tracker worked without a hitch.
And even in flight it became clear that the USB cable that connected the telemetry module with Raspberry Pi 3 turned out to be defective. He worked on the ground, but refused in the sky. Probably scared of heights. We found out the fault of the cable after the landing. Fortunately, it was possible to establish data transfer directly from the telemetry module via LoRa.

And about a good

Luck smiled at the hubriasers @ severov_info (first place), @ MAXXL (second place) and @ evzor (third place)! The luckiest one in November is waiting for a lot of impressions (hopefully pleasant) from Participation in the sailing regatta AFR , and the owners of the second and third place, we will soon present a good smartphone. And of course, all three of them are free to rent a virtual server from RUVDS.
As the launch took place, you can see in this small video:
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