MK GPS V3

It will interesting to see how this works in different parts of the world.

By the way if you want to be a beta tester holger says

"Who wants to test one of the few modules asap, should purchase this Test-Artikel and leave a comment "MKGPS V3" while ordering.
Some parts of the module are assembled by hand and it comes complete with mounted GPS Shield."

 

Adam,

Love to hear back on this. I have been having some weird issues with my MK GPS's on both rigs. It's not a major issue but every time I take the hex off I lose GPS (Error 21) for about 10 seconds. Then have it back the rest of the flight no problem. It starts out with 6-12 sats, goes to 0 after take off and back to 6-12 once I am 10 seconds in, altitude has nothing to do with it.

 

Andy,

Yes. Reno, NV is a bit more ferrous then most places so I have always had some GPS issues, they are just getting a bit more common though which is a bit of a concern. It is shielded as well, but the Octo does not experience this as often even UN-shielded.

 

Care to post a photo of what your copter looks like, in particular your GPS location and where your batteries are? It'd be great to see what it actually looks like (meaning battery(s) connected) before it takes off. Do you have an external compass?

 

No worries, I don't have this issue down in SF/bay area etc.Its GPS error 21. Its an internal compass.

 

IMHO, that GPS position relative to those big LiPos could be part of the problem. I've seen small changes in GPS positioning, as well as more careful routing of the LiPo wires, have a positive effect on the quality of signal. Ironically, you can see in the second photo how you can't really see the MKGPS behind the LiPo. And there's an EMI halo around all that stuff, so it'll impact the ability of the GPS antenna to "see" the GPS birds. I'd suggest getting some 50mm nylon or metal standoffs and trying to raise your GPS and Navi boards higher up on that boom and see if that has any effect. Remember you also have the motor wires running through that boom right underneath, so raising the GPS will better isolate it from those, too.

 

And adding the external compass may help, too.

 

Steve,
Moving the GPS down 10mm and its already on a 25mm standoff from the tube.

 

Hi Ryan

From my experience there's 2 things that make a big difference.
1. Make sure the GPS compass physically higher than any part of the lipo cables. You want to make sure the compass is on a higher plane so that it doesn't get into the level of RF emitting. It's hard getting the GPS compass on boom one higher than the batteries (if they are mounted above the flight control board. What I have done is relocated my battery mounting plates to actually the hub level. This does 2 things, it improves the vertical center of gravity but it also helps lower the lipo wires even more.
2. Make sure all your plus and negative cables are together tight. Use either heat shrink tubing or electrical tape. You won't be able to get heat shrink tubing over the Lipo EC5 connector so you will either need to remove the connector first or just electrical tape the wires together for each of the battery cables. Make sure your main power cable that goes from the board to the lipos also has the positive and negative cables together all the way up to the board. IF you run any other power such as lights, FPV, make sure those power cables are also tightly together like your lipo cables. I personally don't braid my motor cables because I find it hard to get a very tight braid on that thick of a cable so I heat shrink all 3 of the motor wires together all the way up to the bullet connectors. Doing all these things really ensures that you have minimized magnetic fields as possible. It's part of all the little details that go into the build.

If you haven't seen Andy Johnson's Rather Good Guide DVD series yet, I highly recommend picking up a copy through Quadrocopter.

In the pictures above I actually have changed the mounting hardware for the compass a bit. I now use 2 battery tray stand offs and use nylon screws that go into each of the standoffs.

 

BTW: What's up with the lady laying down on the curb in that picture?

 

Part of the crew I was flying for. He was getting setup for a shot of the train rolling in.

Dave, I cant get my GPS above my Lipo's Just wont happen on the build. Also, this issue does not show up if I drive 30 minutes to Tahoe (west), 30 minutes to Carson (south) or 30 minutes north to the test field we use for the Uni. Hell we did 2 hours of flying down in Menlo park and did not see the issue once.

 

Ryan

You can obviously experience issues at one specific spot but in general unless you build it right you will have intermittant issues that will have you chasing your tail.

 

Dave,

Its built right. The issue is not related to anything EMI as if that were the case I would not have GPS at all during any current intensive maneuvers. We tested the lorentz field and it measured about 1500 Gauss right on the battery, and 15 at the GPS unit and still got the interrupt and then GPS came back 5 seconds into the flight. Did the octo next and it measured 1500 guass at the battery, and 20 at the GPS unit, took off and had GPS the whole time. Hex is shielded Octo is not.

 

Hi Ryan

There numerous factors that can give intermittent GPS issues. The recommendations Steve and I are recommending are known fixes that work. How good is your GPS hold? Are you seeing any toilet bowl issues? Is the PH locked tight? Looking at the pictures for both copters I see a few issues. Like Steve says the big batteries can very well be blocking a lot of the GPS signal strength. The batteries appear to be blocking about 50% of the GPS signal radius to the GPS receiver.The lipo cables appear to be too long and the positive and negative cables are not twisted, taped, or heat shrunk together. Your Y cable doesn't appear to be isolated either. When your copter takes off you are seeing a major load of current going through the system, this is a current intensive maneuver as much as anything else you can possible do in flight. If you are losing GPS signal on takeoff which is very high current load your wiring could very well be giving you major interference. Based on the fact that you have 2 copters with very similar setups on the wiring side I would guess that there's something going on with the method of wiring that could be causing the issue. It doesn't hurt to eliminate possible issues and try one thing at a time like suggested. These recommendations are only going to make your copter run more reliable.

 

Dave,

No toiletbowl, PH is solid. I can park it above a telephone pole and it will sit for the full 24 minute run time and not move an inch. The batteries are not blocking the GPS (which is 2.5cm below the tops of the batteries) as I always have a solid 11-12 sats. I have eliminated ALL EMI and current based issues. If you would read my previous posts I DO NOT have this issue ANYWHERE outside of Reno city proper (which is a giant magnetic bowl). I have not had this issue in City of SF, in Las Vegas or in Salt Lake. I have flown the hex for aerial photography in a city where I have buildings blocking GPS and not had the issue. The reason I asked my first question is because GLONASS and the Chinese GPS sats would add strength over my area and would help offset the natural magnetic force that Sierra's (high in iron) and Reno (high soil iron content due to erosion of said mountains) have. Here is the kicker, I JUST took the un'sheidled GPS off my octo and did 6 flights, no signal loss. Took the shield off the hex GPS and re-installed. 6 more flights No signal loss.

 

I did Read your posts. From the info provided prior to #17 I made my recommendations based on what was provided. Good luck hope you figure it out.

 

Then you've answered your own question: gremlins. Personally, I don't care for Reno so it wouldn't bother me all that much.

 

Hi Ryan sorry you may know all this but, big big warning those nice looking Tiger motor cone nuts DO come off don't ask me how I know. ugly locknuts are way more reliable and secure , for me the cone nuts should be outright banned
if you don't change them at least remember on every every flight tight them,