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Lesson's Learnt

Posted by Aran Fitzgerald on August 13, 2013 at 6:30am

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° Don't leave your model in a car in the middle of summer if your principle construction method is hot glue


° 3D LOCK DOESN'T MEAN JACK - you absolutely need telemetry so that you can track your GPS location and wait for it to settle down. Since the crash I have seen the 3D lock jump 30m and back within a few seconds. Almost surely this was the reason for my model rocketing off (I got a 3D lock after 20s or so in a completely new location).

Finally...

° There are HD cameras and then there are cheap HD cameras. Cheap HD cameras are not HD, no matter what the video resolution output is. HK HD WingCam I'm talking about you. $40 wasted on you when the 480p keychain for $7 makes better video.

 

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  • Aran Fitzgerald August 19, 2013 at 2:23pm

    Hi Thomas,

    I have in fact discovered that it was activated as per the standard logic. What I didn't know was that one really must install the 3DR firmware. So I spent some time doing this. Although it didn't change anything with respect to EGNOS, it did activate aircraft / airplane mode for the NAV5 parameter. NAV1-4 were still automotive though, so don't know how that is selected.

    Anyone know what the difference between NAV1-4, NAV5 and NAV5x is?

    I have not however been able to test yet, my life with 3 young kids, job, wife and organising moving the family back to Australia... well need not say more I think. 

  • Gary Hunkin August 16, 2013 at 9:39am

    With these low cost CA code GPS receivers static or low speed accuracy  will only be sub 20m from the true position. A good way to get them back to a better static position is to reset them and wait 5 seconds after it gets a fix. You can compare the position before and after this reset and somtimes it will jump up 100m to the true position. This is only if you are standing still or moving very slowly. Any form of position pinning should be dissabled in the GPs, accelerometres should be used to confirm if the unit is moving or not.

  • Vindolin August 15, 2013 at 6:45am

    @Aran no because there are different SBAS systems around the globe and you have to select the one that you want to use.

    http://en.wikipedia.org/wiki/Satellite-based_augmentation_system#Sa...

    and configure your ublox with a serial adapter and the ucenter: http://www.u-blox.com/de/evaluation-tools-a-software/u-center/u-cen...

  • Aran Fitzgerald August 15, 2013 at 1:46am

    http://www.kowoma.de/en/gps/waas_egnos.htm

    OK, I get it. This is a very good description of EGNOS. Maybe if I bought the module through HK, EGNOS is not automatically on.

  • Aran Fitzgerald August 15, 2013 at 1:26am

    Hi Thomas, no I haven't. What does it do? Honestly, I haven't changed the 'as sold' configuration on my Ublox.

  • Randy Ram August 14, 2013 at 12:09pm

    I have a APM2 sitting and wondering how good would the accuracy of the built-in gps be? How does it perform with the new 3.0.1 version?

  • Wipo August 14, 2013 at 7:47am

    I got the same gps issue with a sparkfun sup500f. Before you take off check the gpshdop value. If it is > 2 then don't take off. And also verify your location on the map via the mission planner. But for this you'll need telemetry hardware and a groundstation (pc, tablet, smartphone,...)

    For the HK HD WingCam (720p). I have this item and the video's I got are much better then the vidoe's from the RCmodelreview website. Because there video is blurry I guess they have a faulty product or a bad lens. The wingcam is in fact a RD32 sports cam clone. Maybe there are multiple version of this WingCam. Because the hd wingcam on rcmodelsreview has a green PCB and the item I got from HK has a red PCB. I know that the color of a PCD doens't matter, but this indicates that maybe different version exists.

  • Vindolin August 14, 2013 at 7:29am

    @Aran: have you tried enabling EGNOS?

    http://www.navilock.de/dyn/faq/uBloxEgnos.jpg

  • Aran Fitzgerald August 14, 2013 at 2:52am

    Hi Magnus, OK. That's really given me food for thought. I would be surprised really if they are really that bad considering the specified resolution. I also have my GPS mounted close to an ESC. Since my airframe is essentially mini scale I don't have much space for stuff so I ended up putting my GPS on right next to an ESC. Maybe this really is a bad idea. I'll try to put it on top of the APM (crius in my case) maybe this will be better.

    Food for though and some good tips. At least now I know that I should expect much better performance and I can keep trying until I get it. 

    I will definitely invest in telemetry now that I know that this stuff needs to be troubleshooted to this degree. i'll have to upgrade from a mini to normal scale copter also. I don't think I can lift any more stuff! I already have an amazing amount of gear for the size.

  • Magnus von Rosen August 14, 2013 at 1:43am

    That's the one. Just ordered mine actually, borrowing a friend's until mine gets here. His' is the same, from the ArduPilot kit they sell there.

    His worked out of the box, even though I had to manufacture a cable from bits I had here and there. Using the included cable and the cable from you existing GPS, you can do the same.
    Default I think they only do 1 Hz and 9600 bauds, you're supposed to connect and update them to 5 hz and 38400 if I understand correctly. I haven't yet, just so happy with the way its doing now...
    First you might try to move your GPS of course. Iv'e been thinking about that too. For example the Naza systems and others have their GPS on a 15 cm pole up in the air. For good reason perhaps?
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