Replies to This Discussion

Permalink Reply by Daniel Portillo on July 23, 2012 at 12:47am

I have the same problem in two APM2 in two diferent planes one of these has a external MTK far of other electronics and in the same place that I had when I worked with APM1. This me sound to a wrong board desing that do very sensitive to electric noise, because the units work fine out the plane without wiring and rx only with battery and ESC.

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Permalink Reply by Will Snodgrass on July 23, 2012 at 12:30pm

What does the CLI tell you if you don't have a lock? One way of Disabling it is using a 4k resistor and soldering one end to pin 2 of the GPS and the other end to either pin 3 or ground. Then using a ublox. 

Also it seems that 99% of them work fine, it's just that no one ever makes a post about how many problems there NOT having.......But as soon as they have a problem you here about it. There is acutally a troubleshooting forum just for this stuff, (I didn't see until I had already made my post). You will probably have better luck there so the people that can help you see your post. Rather then just seeing it somewhere else

I will however let you guys know how mine turned out and what I learned from the experience that might help you.

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Permalink Reply by Dr Mike Black on July 24, 2012 at 1:08am

Hi guys,

Ok, after 2 weeks of extensive testing, these are my conclusions.

(pics posted elsewhere but may help someone)

Pretty much everything affects the onboard GPS, to a greater or lesser extent.

For me, largly, it is the Data Tx/Rx however, now that i have moved all the GPS units away from main boards things started to get much better.

In an attempt to shield the GPS from anything aircraft drive, I created (what my guys have coined) the 'disk of doom' (dont ask! :) )

Also wrapping the bottom of the GPS in depron covered with alu foil tape....well the differences were astounding..

Sub 30 sec locks on all GPS units (MTK included) and reliable signals, the ublox conversions with patch antennas were stronger, but the Ublox with an MTK patch on it worked extremely well also.

Basically the MTK as standard, any where near other electronics is impared by RF noise.

Interestingly, the ONLY item that deosnt affect it is the 5.8ghz .5w Vid Tx...900, 1.2, 2.4 all create maryhell with it.

(dont worry about the IMU sitting next to it, i used the airframe to hold the GPS unit, a the hole was already there, and to create as much near niose as possible)

I dont know if this helps, but creating a shield from internal noise has done the trick, i would now trust it and am about to fly the APM2 again.

For the record, you dont have to make anything as ugly as what i have done, but a simple apature where the GPS sits lined with alu foil tape. (MAKE SURE YOU DONT SHORT IT OUT EITHER!...lol)

I have also now removed all my MTK's from the APM2's as here, where i am, i just cannot get any reliable results.

Honestly for those having probs, this work around is pretty simple, you just need to shield the GPS from the rest.

Again, this is just my personal conclusions, and clearly some are having success as standard, if not, try this, it may help.

Kind regards,

Mike.

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Permalink Reply by Jake Stew on July 24, 2012 at 11:49am

Thanks for doing all this testing.  I'm sure it will help people out.

I get great performance with the stock integrated setup on my APM2, but I have experienced problems with other MediaTek modules and it's always a pain figuring out the problem.

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Permalink Reply by Jeremy Gore on August 14, 2012 at 5:40pm

I have a similar problem.

From New my APM2 got gps lock maybe 4 times. Took 10+ minutes each time to do this.

Now... I dont get a lock at all.

I have not been able to use the APM2 successfully since new. I emailed tech support, but got no reply.

Whats the general course of action here?

I'm not going to justify buying a new gps module for it because the original has never worked properly!

Should be a warranty job as far as im concerned.

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3D RoboticsPermalink Reply by Chris Anderson on August 14, 2012 at 6:08pm

Jeremey: How are you powering the board? If it's any higher than 5.2v, it can lead to GPS lock issues. 

As for tech support, which email address to you send it to? Was it help@3drobotics.com?

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Permalink Reply by Jeremy Gore on August 14, 2012 at 6:17pm

Hi Chris,

thanks for the reply.

Yes thats the email address i sent my concerns to.

As for powering of the board, I have the jumper on the board in the default position and I have had it powered only via a usb cable on a laptop so i could actually see the satellites and hdop in the mission planner. Also have tried it powered via the esc as normal.

The original times i got a gps lock was powered via the esc. But it has had a maximum of maybe 4 gps locks since new. It hasnt got a gps lock since.

I have tried it powered via different escs. I have a Turnigy BEC somewhere, Should i try that?

I read you can update the firmware for the mediatek modules, Can you do this for the one that comes stock with an APM2?

Thanks for your assistance.

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3D RoboticsPermalink Reply by Chris Anderson on August 14, 2012 at 6:19pm

And you've been testing outdoors? It won't work indoors. 

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Permalink Reply by Jeremy Gore on August 14, 2012 at 6:23pm

Yes definately. Latest times have been via usb with the laptop outside on the grass in the middle of a paddock with perfect sunny skies, no clouds etc.

Eagletree OSD gps (which looks like a mediatek too) gets 8+ satellites after a minute or so.

.

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3D RoboticsPermalink Reply by Chris Anderson on August 14, 2012 at 6:25pm

Please email tech support again. The ticketing system was down for a few days, but is back now.

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Permalink Reply by Jeremy Gore on August 14, 2012 at 6:30pm

Thanks Chris,

I just sent them off another email.

I will see how I go.

Ive seen lots of videos of the APM2 on quads and planes and am keen to get it up and running :)

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Permalink Reply by cxgiacomo on September 10, 2012 at 5:30pm

Chris, I find it hard to believe that after 10 pages of people expressing virtually the same problem, the problem is unique to one person. Does this not warrant some investigation from the developers? There seems to be quite a large community of people now with GPSs that had no problems, and now just flat out won't connect. If this must be done individually, then i will likewise join the customer support conga line, but that doesn't seem to be the case here.

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