Replies to This Discussion

DeveloperPermalink Reply by Andreas M. Antonopoulos on June 21, 2012 at 1:54pm

Where are you located?

It might be more feasible to add an external GPS instead of repairing that one

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Permalink Reply by Anders Hansen on June 21, 2012 at 2:35pm

Hi,

The same happened to me after an heavy impact.

I managed to fix so that it was able to function again, but the rest of the card was so smashed that I didn't dare fly with it again.

Anywho, here is how i fixed mine:

1. Put som soldering tin on, the center connector (the antenna connector)

2. HInge the GPS antenna on the two horizontal holes (bottom of gps in the picture, in the gold part) on the GPS-base.

3. Have a friend help you to hold the GPS antenna in a 45 degree angle

4. Heat up the soldering tin, count down so that the moment you pull the iron out your buddy lowers the gps-antenna onto the melted tin. And hence reconnecting the whole thing.

5. The thing is now very fragile so i used a gluegun to fix and support the antenna by gluing all the way around.

(I have also done this with my current board as it serves as a good support structure in case of a new crash)

6. Voila, you now have your GPS back :)

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Permalink Reply by firerescue41 on June 21, 2012 at 4:08pm

Thank you I will have a go at that. I am not a big fan at trying to take the GPS off or removing the trace wiring but if worse case i will use external GPS. The APM function  just fine but no GPS. Thanks for all your help

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Permalink Reply by vUAVman on June 21, 2012 at 6:58pm

I've experienced this too. 

For APM 1 there was wooden box "Ardupilot Mega Case" designed by Peter Koppendorfer that was great at protecting the APM from crash impact.

When testing hardware I use a KK board ($20) and then when the most of the kinks are worked out I switch over to an APM ($200).  Surprises still do come up and the detachment of GPS antenna on the APM2 shield was my first (surprise for APM 2).

The solder repair proposed by Anders Hansen looks promising.  External GPS is another work around.

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Permalink Reply by firerescue41 on June 22, 2012 at 11:42am

I tried Anders Hansen fix but was unable to get it on. This is my next attempt at fixing it. With this setup I get 6 to 8 Sats but no GPS lock. I do not believe I have the right location for the ground wire any help would be great.

Thank you

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Permalink Reply by Anders Hansen on June 22, 2012 at 12:47pm

Hi firerescue41,

The fix you are doing there is very suboptimal as the long wires will mess up the characteristics of the antenna. This is espescially important on high frequency applications such as GPS.

One thing I was thinking about if I hadn't been able to fix it my way was to buy some conductive ink (like the putty you fix the heating threads in the rear window of your car). Dab that in the middle and again fix with glue around the edges..

(Btw: Try to test the APM2 just by powering it from usb, and have it outside for a GPS fix Wait for at least 10 minutes. Kinda strange since you get lock on 4 satellites)

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Permalink Reply by Zachary Eldridge on June 22, 2012 at 12:53pm

When has 3DR stop doing repairs. They fix a few of my stuff that was not working really cheap. However, wait time was long.

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Permalink Reply by firerescue41 on June 22, 2012 at 3:21pm

you are right about the messing with characteristics I get  a 3D GPS lock and 8 sats but looks like about 50m off location accuracy is off. I will look into the conductive ink do you think it would help if i used shielded wiring that may  help or is the wiring acting like a db gain on antenna. I know nothing about GPS antenna only VHF antenna systems. 

Thanks for all your help 

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Permalink Reply by Anders Hansen on June 22, 2012 at 3:30pm

It is the same theory which implies to the GPS antenna as for VHF. The only difference is the frequency, GPS is ~1,5 GHz, compared to 30-300 MHz in VHF systems. And when one enters the realm of GHz communication things realy start to get tricky, as the margins is much smaller. So I think the shielded cables wont do you that much good anyway.

But it is strange since you get a lock the antenna should be ok enough really. Have you checked the LAT LON against another GPS (ie your smartphone). It might be that the maps are 50m off, not your GPS ;)

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Permalink Reply by firerescue41 on June 22, 2012 at 3:37pm

Good info I will check with hand held gps did not think of that.

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Permalink Reply by firerescue41 on June 22, 2012 at 4:35pm

Andiers I hope I am not bothering you to much but I thank you for all the help. I used a hand help GPS and it was spot on. If I cut the wires down a lot shorter then they are now and use a glue gun to secure it to the board do you think that would cut down on some of the noise?

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Permalink Reply by Anders Hansen on July 22, 2012 at 8:44am

Hi firerescue,

Sorry for the extremely late answer. Didn't notice that you had posted again.

To put it simple the closer you are to the original design the better the GPS performance;)

One thing you can do to check for noise and other performance issues is to analyze a know path, ie fly in a straight line or a square. Dump the log into your computer and look at the path recorded by the gps. As long as there is no large discrepancies you are good to go.

Happy flying!

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