APM 2 GPS not getting a lock?

I have been sitting here trying to get a lock with my GPS while outside for about 10 mins.  No luck.  I generally get a lock between 30-60s when outside.  My GPS has worked fine previously.

Other than the CLI test (which only works if I have lock anyway), is there a way to check GPS function?

If my GPS unit turns out to be no longer functioning, what options do I have with the APM2?  Since my GPS is soldered directly to the board, is it possible to get another and use an extension?  I don't trust my soldering abilities enough to remove and replace the current unit


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  • Hi,

    I asked earlier but did not get an answer, that is, what is the typical HDOP you all are getting? I finally got my external GPS to get a 3D lock and about 8 sats BUT the HDOP was in triple digits! As I recall HDOP needs to be less than 4 to get reasonable accuracy.



  • My GPS worked fine on my "test bench", being my balcony as my unit has a metal roof, but failed to get a lock once installed in my plane. After some testing this evening I found that it received interference from the video cable coming from my FPV camera. So much so that I could get a lock with 5 satellites (not bad for my balcony), put the GPS within an inch of my video camera and it would immediately lose the lock and drop down to 2 sats, then move it to 2 inches away and it would go back to locked with 5 sats within a few seconds.

    Needless to say I'm making some alterations to my cockpit layout. :)

  • ¿It is possible to power the gps alone? if it is, how?

  • Hi All,

    This is my first post to the forum. I have been fairly active on RCGroups but not much going on there wrt APM2. I have read this thread with interest as my APM2 arrives today. I have several other "osd/autopilots" but none with telem capability, ergo the APM2.

    To the point...none of my other equipment has ever had an issue with GPS lock, so it is disconcerting that the 3DR APM2/GPS seems to have prolific issues. With all due respect, data points to a design issue, either radiated or conducted emissions from the APM2. When I get my APM2 I will set up and post back results. I have an RFExplorer and can at least "see" if there are some radiated emissions created by the APM2. However, until the new SUB3G module comes out, I can't detect frequencies of interest, i.e. L1signal.

    btw, there are 24 GPS sats in a constellation and there are 31 sats on orbit that are functional. There are additional sats on ground for launch as needed. So it is unlikely that GPS signal strength is part of this issue. And, as I said, my other equipment cold locks in less than 3 mins.



  • I have the same problem whit the gps, i read this post and make the following test:

    With the generic ESC 60A 10 mins, nothing, with the usb 2 mins locks, with another esc Dualsky 30A (but small for my plane) 2mins, lock, I want to buy a Dualsky 60A to test What do you think if i can solve my problem like this change? 

  • Ok guys,

    On friday i de-soldered (somewhat creatively, but lets not discuss that right now :)  ) the removed the MTK from the APM2, wasnt as hard as i thought it was going to (and can be re-soldered back if need be)

    made up a 1m long extension lead to get the MTK as far from anything as possible, used a very nice supply to keep things even and smooth.


    MTK locks up much better, quicker, and is more stable...however...

    it drops out still far too easily and as soon as you bring servos, video camera, and worse of all, Vid Tx any where near it, the problem is back in less than 6 secs.

    my honest opinion of this is that, the MTK is a good GPS and is sensitive, but outside influences, affect its ability to do its job far too easily, I personally would not trust my UAV/FPV ships to this unit.

    If it helps anyone, i am using the older LEA5H ublox units and are rock solid, lock in sub 30 secs (you must ignore teh blue LED on teh top board, as its permanently on, but the blue LED on the base board gives you a true reading of lock or no lock.

    There is another sub issue here, that needs investigating (in another thread perhaps), when the ublox is attached to the APM2, the artificial horizon moves around it centre point even with the board locked still when setting up, this may be  a power issue though, but its def apparent with external GPS connected.

    Hope this helps in some way.

    Kind regards,


  • Clearly you didnt get what point the others were making and the point i was making.

    You didnt get it then, you clearly dont get it now.

    You have made assumptions based upon limited information, about the GPS, the APM's and the people working with it.

    No one is complaining about the GPS, but trying to get to the bottom of the issue, and figure out EXACTLY what is going on.

    The only people that can comment and therefore interject in this thread are the poeple experiencing ths problem and those who created the APM2 and thier decision to use this particular GPS.

    (which is as i understood it, was WHY this was raised in the first place.)

    For the record, the GPS units i am comparing against are the Ublox LEA5h (all 7 I have are 2-3 years old, so clearly not shinny and new) Locosys x 5, and a stand-alone MTK's on DIYd boards.

    I have no idea whether your explanations (which are very thorough by the way) are the very reason you cannot accept the glaring conclusions or whether you work for 3DR or mediatek.

    Either way, this is not solving the problem, nor has it invited the manufacturers to join in and offer some information.

    also on a personal note, i really dont like being patronised, im not sure if it is intentional, or just the tone you have used by default.

    We are all here to help and grow, and this helps no-one.

    Personally, perhaps you are asking the wrong question, and therefore making the wrong assumptions, as none of us in this thread are barking up the wrong tree, we are trying to deal with the APM2 and its GPS issue, not define the reasons why Nasa has been shut down or that the USA alone is responsible for the GPS satelites (which they are not).

    Did you ever wonder what my Phd is in? I do this for a living and I am confused, and i am not alone!

    As a moderator i must draw a close on the X-posting of issues not relating directly to the aforementioned.


    @ Michael, If it helps, the same GPS units have been tested on the original AP (which i was part of the development team) and the issue still exists (In my personal experience)

    In my testing, 90% of the ESC's/BEC's out of china  are from similar companies, and only a few are really bad on RF noise or smoothing of the output.

    With the APM in parrallel on the same PSU, as a working and locked AP, it still exhibits the same behaviours, we need to be looking at something else.

    I would dearly like to remove the onboard GPS units and test the fitted ones away from the APM itself just incase there is something inherent on the board that is not know yet....In fact tomorrow i will do exaclty thay, see if there is something we are not aware of yet.

    Random has no memory, so maybe, its just a quirk that becomes obvious in certain circumstances, but i have not yet been able to yet get a set of behaviours consistent with each other, to create a chronology of what deos what and in what order.

    Again, it would be really good if the makers would jump in here and share thier experiences, as there is no way that we are alone, and they must have some gained data that they can share.

    Kind regards,


  • Is anybody here having this GPS-Lock problem with original Diydrones ESCs and/or original PDB? Maybe it is the cause that some ESCs emit strong interefrences and others don´t.

  • Vernon, if the solution of the problem is so simple, would you tell us what BEC / UBEC supply clean power? Maybe we can create a list with good parts and bad parts. But I think the solution is unfortunately not so simple.

This reply was deleted.


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