T3-4 Photocontest using EasyUAV from brakar on Vimeo.
This thread explains things:http://www.rcgroups.com/forums/showthread.php?p=14059833#post14059833Compare how few satellites over the horison can fool navigating plane.You need to be a member of diydrones to add comments!
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Also turn left lost more than turns to the right.
http://www.sarantel.com/downloads/specifications/geohelix-s.pdf
Page 2 shows 'radiation pattern' and how much the gain drops off when not 'pointing' directly at a satellite.
You 'should' be able to see what really happened if you plot time vs 'sats in view' and roll angle. There will likely be a reverse correlation.
Mungewell.
When performing a mission you can:
1). Improve the number of sats by flying at a different time
2). Improve the number of sats by using a GPS/Galileo system
3). Improve the number of sats by flying at a different location.
1) & 3) are probably impractical given a 'mission', 2) costs a fair chunk of money.
So you have want you have and you have to make the most of it. I think the biggest issue is not that you only have 6 sats, but that you 'lose' half of them when you bank/roll due to the reception pattern on the patch antenna.
Assuming that the body of your aircraft is RF transparent (most likely) then mounting the GPS/antenna on a small servo which rotates in the opposite direction to the roll may aid reception a great deal. Pitch would probably not be so much of an issue as the altitude would be fixed.
If you are doing ground photography (as in the contest) then you may already have the gyro signal required from the camera stablisation system.
I just got (at work) a couple of the LINX GPS modules (http://ca.mouser.com/ProductDetail/Linx-Technologies/RXM-GPS-SR-B/?...) and boy are these things small. SiRF Star binary support too. These would be easy to mount with some glue/double sided tape.
Mungewell
Moving from Norway???
Or if you had a piece of string on a reel tied to the launch point you could count how far from launch you had flown, perhaps black and white string with optical sensors counting the black and whit bits. Or some obstruction or knot in the string that you could count as it bumped over something. Then for RTL all you have to do is winch the plane back in.
Its a tricky subject this, and its only now that people are getting out there and using there UAS frequently that we are taking note. A growing pain!!
I have my GPS buried in the top of the wing, clear view of the sky seems to work, you have to wonder about peeps that put theirs under the wing of a high wing trainer, I have seen it a couple of times.
For me flying most days I notice when it takes ages to get a lock.
However in this case Flexipilot has seen more than that before launch and gave the green light...
The GPS is on the tail quite far from the motor, has separate power supply etc. Only the BEC brakar has installed could be possibly blamed, or something else, maybe in order to improve reception pattern, maybe fly higher at 200agl...
But Chris is right, more than one factor to take into account when going out to fly. Proves his system works if there's time to think about other things!!
It should be part of the flight planning in the GCS really, make your flight plan, choose a time of day to fly, then let it tell you if its a good idea or not.
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