Replies to This Discussion

Permalink Reply by Leigh Green on July 19, 2012 at 7:15pm

Ok going to double post this - cause it's a bit of a rant - having just received my APM - GPS reception is dubious..

 

...Not sure what the go is, as I have been using GPS devices for many years, I developed a tracking system with Franson many years ago and use SANav devices, and leadtek, and even Nokia...all have fantastic GPS pickup, but the Mediatek onboard seems a little insufferable.

I have seen so many suggestions of "unplug your receiver" and remove your ESC, etc...but if these are all solutions by the time I'm finished the only thing that will be in the UAV will be the APM itself - it can't be a solution to remove all other electronic equipment just to get the GPS to pick up more than 2 sats.

OK - a bit of ranting there, but then that being said early on in the evening (I'm guessing it was before the clouds rolled in.) I did have good sats (6 I think.) and was getting to within 3-4 metres without much drift...interestingly right before I got nothing I started to see my plane icon in mission planner slowly creaping north until it was over the back fence of the neighbour across the road.  Althogether not to bad really...But I suppose the reason I am posting this is...HAS ANYONE...managed to increase the pickup ability of the Mediatek GPS - whether onboard or offboard by changing the antenna...

What I've seen is every manufacturer is SO very proud that their GPS is smallest on the market with small Ceramo-helical GPS Patch antennas smaller than my thumb.   But the reality is I am not THAT void of space that I can't afford a few more mm for a bigger antenna.  SO my question really is, is there any merit or harm in creating an external antenna to attach to the GPS module...and if so does anyone have any plans/calculations like iBcrazy's CL and SP antennas...

 

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Permalink Reply by Tony Heaton on July 19, 2012 at 7:59pm

Looks like going with the external uBlox LEA-6H GPS may be the way to go.  I was told by sales that I could use an external GPS even with the built-in Mediatek GPS in place.  Hopefully that will work.  If I have trouble, I'll try an different antenna if possible first and if that doesn't work I'll order the uBlox.  I've had my scratch built frame, with motors, ESC's, and batteries ready to go for two weeks now and I'm ready to get flying.  I'm not going to rush things though.    When I get going, I'll post some pictures and results.

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Permalink Reply by Leigh Green on July 19, 2012 at 8:47pm

LOL...yeah I started my scratch built UAV a couple of months ago...ordered APM...started to get fidgety and in the mean-time built 3 other scratch builts, including a couple of sflying wings just because I had a tonne of foam waiting for me to knife it!  Now I need to get a couple more APM's cause I've got too many potential FPV units lying around...haha

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ModeratorPermalink Reply by Carl Campbell on July 19, 2012 at 8:59pm

Just a Thought.  A severe X class solar storm hit earth Saturday evening, It could be that when we entered residual plasma again about dusk that the GPS signal may have been interfered with. 

This is just a theory.  http://www.huffingtonpost.com/2012/07/13/x-class-solar-flare-sunspo...

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Permalink Reply by Leigh Green on July 19, 2012 at 9:39pm

The only flaw in that - as we do know SF's do indeed cause disruptions on that scale, is that was a week ago and we don't pass that region of space for another 360 days, which since the plasma is ejected at a good 3 Million MPH it's unlikely any residual is still floating around as it was either absorbed and redistributed by the Ozone, or subsequently bounced off or flewby without so much as a goodbye on it's way to bombard Jupiter.

That's not to say there are not other minor Solar disturbances causing just as much havoc, but I can't see a thousand people in cars this morning banging their GPS's screaming that they are lost.  Yet here am I driving with the APM on the parcel shelf of my hatchback and laptop in drivers seat driving to work this morning and no more than 1 sat for the 20 minute drive.

But here is the clincher - the weather has cleared up by midday and having the unit on a shelf in my office (for which my Lenovo laptop with built-in GPS which is quite good at getting signal is always struggling in this office.) - connect my Xbee again and check the signal - I hit 10 sats and I think down to 92 hdop.

So the conclusion might simply be that the Mediatek is no good when teh clouds come over.

That in itself is a problem because they were not rain-clouds so with no wind I might be flying, but of course I can't as I have no GPS sats.

My aim to this end is to try and improve the inherant sensibility and pick-up of the existing geoHelix patch connected to the MTK.

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Permalink Reply by Søren Kuula on July 19, 2012 at 10:17pm

Hi, in other systems adding a ground plane - a piece of tin sheet - under the GPS rx has improved reception significantly. Eg. MikroKopter "GPS shield". I would give that a try. Regards, Søren

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Permalink Reply by Leigh Green on July 20, 2012 at 3:47am

Get this - 12 Sats on the way home in 70 clear skies with large Cumulo Nimbus mottled coverage - put ALL gear bag onboard, Receiver, ESC, Servos, minimOSD, xBee 900mhz, put it on the parcel shelf, laptop on passenger seat Mission Planner open.

It took a few minutes and 5 or six kms before getting 4 sats and only locked once I had 5.  but from there I heard Servo 5 & 6 (i've dedicated to camera mount p&t) whirring each corner I made, and was even able to specifically tell Camera to "point over here" and then you hear the servos doing microadjustments until you pass quickly by the landmark you painted and the servos go crazy to keep on target.

This is all amazing stuff - can't wait to put it into a bird and get it up.  But anyway looks like the Mediatek is indeed OK - just not best performing under poor cloud cover.

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Permalink Reply by Jason Willis on July 21, 2012 at 9:13am

It would be nice if 3Drobotics answered their email! I have placed a bunch of orders this year without any problems but now my new GPS isn't working so I started emailing 3DR on Wednesday and can't get a response. 3DR is seriously lacking in customer service!   

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3D RoboticsPermalink Reply by Chris Anderson on July 21, 2012 at 10:08am

Jason: I'll ping the customer support desk and see if I can find out what went wrong in this case. 

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Permalink Reply by Jason Willis on July 21, 2012 at 10:10am

Thank you Chris!

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Permalink Reply by Mike R. on July 22, 2012 at 8:05pm

Jason, it seems that they are having some... hiccups from at least my experiences thus far..

A few days ago I posted within this thread a few issues I was having with lack of communication regarding APM2 orders, and an issue with a shipping refund that had been perhaps put in the circular file..

I'm happy to say one of the issues was resolved fairly quickly, but another has cropped up..

The shipping charge that USPS refunded to 3DR due to a lost package that they misplaced for a day on overnight delivery is being refunded back to me as per a call from 3DR customer service on Friday - I very VERY much appreciate the fact that they called to let me know. A big thank you for taking the time to do that.

A second issue has cropped up though. Lorenzo at 3DR messaged me here in the forums and asked if I could directly email him concerning my experience with customer service. I did so, and explained the back and forth I got with the shipping charge credit, as well as asking if he could assist me in getting an RMA for a bad oilpan I received with my kit (The baro sensor gave random readings for a few days, then quit completely, never to come back.) I received a fast email back (of which I appreciate) and was told that what I experienced with the shipping charge ordeal was apparently ok with 3DR as it was standard practice, and that I would have to email help@3dr and explain what was going on and ask for a replacement and an RMA # for the old one. While I appreciate the info, after all the crap I've been through back and forth and even just for the reason that he contacted me personally and asked me to email him details, you would think he could just have forwarded the email I sent him to help@3dr, but no, a few more hoops I need to jump through. Ok.....

I emailed help@3dr Friday asking for an RMA # for the bad oilpan and asked if there was a way that I could have a replacement sent to me quickly (they still had my overnight shipping charge in their possession) and if so, please let me know as I need to get this copter back up in the air by mid-week this week to not lose money on a project I'm working on. A few hours later, I received a reply from someone at 3DR letting me know an RMA number, and said I should get a fedex return label via email that day, and to reply to them if I don't get it by the end of the day. I was also told the new oilpan would "ship soon" - whatever that means. So I thought I would get a ship notification later that day, but did not.

After midnight Saturday morning, I emailed the address back (as asked to do so) stating that I never received a fedex email at all (not in inbox/spam/outer-space, etc..) and asked if they could at least let me know when the oilpan would be shipped, and that I would even pay for express shipping if needed as this is extremely important to me.. I CC'd this email to Lorenzo.

I received an email from only Lorenzo a little bit later (I had gone to sleep, so I got it Saturday morning) stating that the oilpan would go out that day. (Don't know if he meant friday or saturday, as he is located on the opposite US coast as I am, so there is a difference in time) - Saturday goes by, no fedex return label for old oilpan, and no ship notification for new oilpan - and I could have sworn that 3DR is closed on the weekends.

So here I am, confused, and pretty much done with 3DR after all this. I'm not asking for gold here. I'm simply trying to get through multiple hoops that have been set up by 3DR to get an oilpan replacement that never worked properly from day 1 due to a simple sensor issue, and am now getting misinformation from someone who was supposed to be helping. I am a -very- understanding person when it comes to backlogs, mixups, etc, but all of these in a row to one person, and when I say that I'm having an issue, I get even more wrong info?

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Permalink Reply by Leigh Green on July 22, 2012 at 10:01pm

My rant for today - my second 3DR parcel arrived - the Ardustation...

 

Can someone anywhere point out to me where it states the Ardustation is Un-Assembled?  maybe I just missed it, and I'm fine with putting it together, just a little warning would be nice.

 

Just looking at it all it's very basic ATMEga128/UNO - so I might even use a spare ATmega2560 which as ethernet built in and make a Super Mega Ardustation - will post elsewhere with code and plans if I do. 

I'm a dreamer first...and a Do'er in my dreams :)

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