I've modified Phillip Anthony Smith's Mavlink Ardustation to support an inexpensive tilt/pan antenna platform. RAM is very tight in the software so this is not a laptop/ground station replacement and the original software was oriented towards APM. However, I've been flying many flights with Arducopter 2.0.x and this antenna and have gotten pretty good video performance with much less multipath interference. I still use a second Xbee on a notebook with the Mission Planner and that seems to work pretty well with the Ardustation. This link gives some more details, a demo video of the software with some explanation of the added screens, and the software itself for others to play with. The software is a little rough since it was developed quickly before the 4th of July weekend, but it is fun to watch the antenna follow the quad and I wanted to give a little back to the Arducopter community.
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Also - I originally didn't have the antenna test screen to calibrate. I used the actual values from my quad to get the servo values close - so it will be good to get the test screen working better. I think I'll also change the values to represent the true heading and pitch angles.
Just checked it and the 0ngle value varies -10 to -80 when it's pointed about 30 degrees below the horizon. Even when 0ngle is -10 it still is about 30 degrees below the horizon. If the mavlink alt goes lower then it gets down to -80 0ngle but it's still pitched 30° below the horizon. It doesn't go more than 30° down.
Alt setting of antenna tracker is fixed at 260 meters and the copter was at 231 meters but sitting right next to it. It thinks the altitude is lower than it really is because it only has 6 sats and it's indoors. First time a bad GPS fix is helpful :)
I understand the antenna test is backwards but otherwise it's working right? That is what is really confusing me. If the test has a correct range of 90° then it should use those same 90° when in flight right?
I could just reposition the servo arm so that it's level but that's probably not the right way to do it. The max it points down below horizontal is 30°.
I had a user in Australia report issues with the accuracy with range/bearing and I added an alternate algorithm that you can access in the same screen as 0ngle by pressing the center button (displays "al 1") He had tested the alternate algorithm and said the pointing was better. I'm now wondering if there is something up with your location and the lat/lon values. It is helpful that your'e seeing the problem at 100 meters - I was testing last night with much longer distances so I may need to get a copy of a log from one of your flights (either tlog or internal log).
It's definitely not backwards because it does go up when it should but just gradually pitches down as I fly away even though I'm in altitude hold and I see on my OSD that the altitude is steady. If I get 100 meters out, it's pitched down about 20°. I will check what you asked and get back to you tonight.
I just set up an external servo and here is what I found.
In the antenna test, a tilt value of 140 corresponds to a pitch of 0. A tilt value of 60 correponds to 90 degrees up. I varied the altitude from a large value (around 90) over Mavlink to large negative values and the servo stopped at the title value of 140 and did not travel further.
It looks like it works ok for me - except for the weirdness of the antenna test screen. I did not write that portion and had not used it very much and now I realize the guy who did it used the arbitrary values that seem inverted from the physical pitch.
So I'm wondering if your pitch servo is backwards and that is causing the below the horizon pointing?
Check on the second flight data screen and what the 0ngle value is. This should correspond to the pitch value and should be less than zero when the below 0 degrees value happens. I would be interested what the value is when you have the "below the horizon" behavior.
Thanks Heino! Really appreciate it. I didn't see any directions on it but hopefully I did it right. In antenna test I just make sure the max is horizontal and vertical and reposition the servo arm if necessary. If the 90° are perfect in that test then it should have exactly this range in real flight correct? I believe the pan is working that way.
I'll set up a external servo and fake some long distances to see what is up. I won't be able to get to this until later today.
Heino, I did some flight tests with it today and as I fly out it pitches below the horizon less than before but it still does it and the further I go out, the more it points down. I'm using 500,2500. Do you know how I can fix that? I don't understand how it can be ok in the antenna test but in flight it has a different range? I hope it can be solved because I need it for range and it just gets worse the further out I go. I'm using HS-645MG for pitch. Roll is tracking perfect.
I ended up setting it to 500, 2500. It gave me a 90° travel in antenna test. Tomorrow I will see if it still descends as I get further out. Not sure I understand how this setting will fix that though. Isn't 500 and 2500 the servo range? Was it because I was at the end of it's range and isn't linear? The antenna test with the other settings also gave me a 90° travel in antenna test but would descend down as I traveled further out.
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