Jan 22, 2013, 06:34 PM Registered User United States, FL, Tampa Joined Apr 2012 336 Posts I usually always have to wait at least a minute to get to the point of one green, one red flash (my min for take off in GPS) and sometimes longer on my first flight of a flying session. Full GPS lock can sometimes take almost 2 mins. I usually get a bit of forward/left drift immediately after take off but it goes away quickly enough. I think this has to do with having not enough accurate readings of locations to make good calculations on how much to correct. Kinda like when you turn your GPS on in your car when your in your driveway or parking lot, it takes your car moving a bit for it to know where you are in order to give you good directions. Before then it often has you pointing the wrong way or at some point not nesc where your car is. Last edited by dedfish; Jan 22, 2013 at 07:06 PM. Reason: added the word not to 4th sentence to make it more clear
Jan 22, 2013, 07:03 PM
Flying R/C since 1964
United States, IL, Chicago
Joined Sep 2004
3,698 Posts
Quote:
 Originally Posted by dedfish I usually always have to wait at least a minute to get to the point of one green, one red flash (my min for take off in GPS) and sometimes longer on my first flight of a flying session. Full GPS lock can sometimes take almost 2 mins. I usually get a bit of forward/left drift immediately after take off but it goes away quickly enough. I think this has to do with having enough accurate readings of locations to make good calculations on how much to correct. Kinda like when you turn your GPS on in your car when your in your driveway or parking lot, it takes your car moving a bit for it to know where you are in order to give you good directions. Before then it often has you pointing the wrong way or at some point not nesc where your car is.

Obviously I'm not sure exactly how DJI does it, but most GPSs use a "Kalman Filter" to improve their position accuracy. Google it if you want to know the gory details, but basically it is a way to use previous position and velocity measurements to improve the accuracy of current measurements. When you first turn on you don't have any previous values, so it takes a little while before it really settles down to an accurate position. Until then the position reported by the GPS is bound to wander around a bit.

http://en.wikipedia.org/wiki/Kalman_...le_application
Latest blog entry: Using a DX9 to "strobe" LED...
Jan 22, 2013, 08:45 PM
Registered User
United States, FL, Hollywood
Joined Jan 2010
59 Posts
Just sharing the story of my DJI NAZA into the lake.

This is the story of my DJI NAZA GPS, that felt into the water in a lake at 2.5m deep, the cause that I suspect, was a failure of one ESC, one friend jump into the deep of the water and he saw the led still blinking so he take out, incredible he take out and still 2 motor where running.. the following hardware was attached.
1-Gopro2 : dead... still in warranty.. so not big deal
2-Frsky rx w Telemetry: seems to be ok, I have to test at long distance.
3-E-OSD W GPS. not tested
4- 5.8ghz video TX. I am surprised that at least I have some RF out, I have to put video to see if its fully functional.
5-DJI 30A ESC. seems to be OK, I have to put new heat shrink, and test for long time to check for failures.
6-DJI naza controller: Seems to be ok, I have to do a test flight to make sure is fully operational.
7-DJI naza power-supply : OK But USB is not working, have to buy a new one.
8- 800kv tiger motor : Ok after drying and some good lubricant.
9-GPS DJI NAZA: I'll have to test it.
.

# Images

 Jan 22, 2013, 11:26 PM Flying R/C since 1964 United States, IL, Chicago Joined Sep 2004 3,698 Posts OK, I have every intention of flying over a lake when the weather gets better, but I intend to have floats on my quad. Floats saved a nitro heli of mine that threw a rotor blade over the lake. Latest blog entry: Using a DX9 to "strobe" LED...
Jan 22, 2013, 11:29 PM
Joined Nov 2012
2,963 Posts
Quote:
 Originally Posted by kallend OK, I have every intention of flying over a lake when the weather gets better, but I intend to have floats on my quad. Floats saved a nitro heli of mine that threw a rotor blade over the lake.
that's assuming it doesn't land upside down, which it likely will
Jan 22, 2013, 11:33 PM
Registered User
United States, FL, Tampa
Joined Apr 2012
336 Posts
Quote:
 Originally Posted by kallend OK, I have every intention of flying over a lake when the weather gets better, but I intend to have floats on my quad. Floats saved a nitro heli of mine that threw a rotor blade over the lake.
Quote:
 Originally Posted by polix that's assuming it doesn't land upside down, which it likely will
It will at least let you have a chance of recovery.
Jan 22, 2013, 11:35 PM
Joined Nov 2012
2,963 Posts
Quote:
 Originally Posted by dedfish It will at least let you have a chance of recovery.
good point, at least you can see the floats, then you know where to start salvaging Since any copter with floats is top heavy if it's a crash you can be pretty much guaranteed it's gonna flop over, but i forgot to take into consideration recovery!
 Jan 23, 2013, 12:04 AM Fight for the Right to FPV!!! United States, CA, Chico Joined Dec 2010 1,350 Posts Check-out this guy's floats for a water landing (crash)... he uses two floats that deploy on hitting the water and start an lcd beacon. He's also equipped it with a parachute that he can deploy if something happens at high altitude along with a radio frequency beacon transponder thats good for over 5 miles in the event that he goes down. wonder if it will still get off the ground with all that equipment http://fpvlab.com/forums/showthread....ashRC-s-QAV500
 Jan 23, 2013, 12:10 AM Registered User United States, AZ, Tucson Joined Mar 2008 2,288 Posts I have 2 of those water buoys I connect to my quad when I fly over water. They are awesome and really light. At \$17 each, that's very cheap insurance to keep my quad from sinking to the bottom. I was going to use pool noodles but these look a lot cleaner. Each one will lift just over 2 pounds.
 Jan 23, 2013, 12:12 AM Registered User United States, FL, Tampa Joined Apr 2012 336 Posts Cool build. What I learned that interest me the most was the interesting use of loc-line as a soldering jig. I like that a lot. I think I have enough in my aquarium supply bins to make something like that.
Jan 23, 2013, 12:13 AM
Registered User
United States, FL, Tampa
Joined Apr 2012
336 Posts
Quote:
 Originally Posted by jasper7821 I have 2 of those water buoys I connect to my quad when I fly over water. They are awesome and really light. At \$17 each, that's very cheap insurance to keep my quad from sinking to the bottom. I was going to use pool noodles but these look a lot cleaner. Each one will lift just over 2 pounds.
What is the product name? Where did you get them?
Jan 23, 2013, 12:19 AM
Registered User
Zaragoza (Spain)
Joined Jan 2005
94 Posts
Quote:
 Originally Posted by JustPlaneMike Doing some research looks like you have to have either a gprs or gsm sim card in order to call ot text the unit.. Where do you get a sim card and isn't there a cost for this? I have a windows base smart phone. is there an app. like the GPS test pro you mentioned?
Yes, you are right. You need a normal phone sim card, and of course to have GSM coverage in the area where you are finding the bird.
The cost ( at least here in Spain) for a prepaid card is about 3 euro, and a minimum recharge of 6 euro each 6 months. The price for each SMS when it send the position is 0.20 euro.
I donīt know if there is an app for the windows base, but any navigator will work fine.

Regards.
Jan 23, 2013, 12:36 AM
Fight for the Right to FPV!!!
United States, CA, Chico
Joined Dec 2010
1,350 Posts
Quote:
 Originally Posted by jasper7821 I have 2 of those water buoys I connect to my quad when I fly over water. They are awesome and really light. At \$17 each, that's very cheap insurance to keep my quad from sinking to the bottom. I was going to use pool noodles but these look a lot cleaner. Each one will lift just over 2 pounds.
Wow, that is cheap insurance. I finally broke-down and invested in the radio beacon for lost models that he uses. The initial investment hurts, but the little beacon is easy to transfer between planes and quads so you only need to buy one. Range is 5 miles on the ground and 40 miles in the air. Comes with a pistol grip transponder similar to what you see the guys use to track animals with in the wild, and uses the 250 mhz frequency so it won't interfere with any of the other equipment on our setups. One battery will last for a week. I just figure my first recovery and it will have paid for itself.. Will give me a lot more confidence to fly in remote areas, and just a lot less overall worry when out there having fun... That's the one thing I didn't like about all the GPS trackers is that you have to be somewhere that has cell coverage or they are useless.. This system is just iron0clad and has the least amount of variables that could get in the way of you making a quick recovery. Here's the link to mine. I highly recommend it for anyone doing a lot of FPV in remote areas or anyone that just plain refuses to deal with the eventuality of a lost rig... Happened to me once.. but never again!!

http://www.com-spec.com/rcplane/index.html
Jan 23, 2013, 01:14 AM
Registered User
Australia, VIC, Melbourne
Joined Dec 2012
320 Posts
Wow dedfish, that's cruel. You need to come to Oz...I get 1 maybe 2 reds immediately after my 4 greens and I'm off without waiting. Maybe I'm just lucky?

Quote:
 Originally Posted by dedfish I usually always have to wait at least a minute to get to the point of one green, one red flash (my min for take off in GPS) and sometimes longer on my first flight of a flying session. Full GPS lock can sometimes take almost 2 mins. I usually get a bit of forward/left drift immediately after take off but it goes away quickly enough. I think this has to do with having not enough accurate readings of locations to make good calculations on how much to correct. Kinda like when you turn your GPS on in your car when your in your driveway or parking lot, it takes your car moving a bit for it to know where you are in order to give you good directions. Before then it often has you pointing the wrong way or at some point not nesc where your car is.
Jan 23, 2013, 01:22 AM