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Old Apr 06, 2012, 01:30 PM
KY3JBD
lebanon, PA
Joined Dec 2000
618 Posts
Hello, i just did my first FPV flight with 200mw TX and RC305 rx with bluewhip antennas. Reception was great, matter of fact it was so good that my twinstar got so far away my spotter could hardly see it and i had to turn back before i got lost. Only time i had a fuzzy picture is when i flew over some huge power line towers. So far i am really impressed with this setup!
Chris.
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Old Apr 06, 2012, 01:32 PM
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Romania, Dolj, Craiova
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Quote:
Originally Posted by markus123456 View Post
...i suggest to organize a very clean 3.3volt power source (for a quick hack, a 1s lipo with a linear voltage regulator but don't try without the regulator as you otherwise will fry your module) ...
...
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Old Apr 06, 2012, 01:51 PM
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I know that I am using this module : http://www.foxtechfpv.com/product/5....23-Spec-V1.pdf

And I was thinking that a 3,3 V UBEC like mine (http://www.hobbyking.com/hobbyking/s...ly_6_23v_.html) would do its job.

So you think its best when I change my power source from UBEC to a normal voltage regulator ?
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Old Apr 06, 2012, 02:00 PM
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You could install some capacitors to clean up the signal...do you have the channels correctly set?
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Old Apr 06, 2012, 02:09 PM
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Switzerland, LU, Buchrain
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Quote:
Originally Posted by Airbuzzler View Post
I know that I am using this module : http://www.foxtechfpv.com/product/5....23-Spec-V1.pdf

And I was thinking that a 3,3 V UBEC like mine (http://www.hobbyking.com/hobbyking/s...ly_6_23v_.html) would do its job.

So you think its best when I change my power source from UBEC to a normal voltage regulator ?
A UBEC does not have to generate a power train as clean as you need it to process an analog signal like the TV signal. There might be such products which are very quiet. There is nothing wrong with the UBEC aproach per se, but you would have to take aditional measures to clean it's signal.

The voltage regulator alone, when fed from the main battery where the ESC is connected to would also not work. You need a combination of DC/DC (read UBEC) to bring the voltage down and aditional filtering to do the trick. One aproach is the daisy chain a UBED (DC/DC converter) with a following linear (low drop) voltage regulator. But that would be a "final" aproach. I think we now have to find out what's going on first and get there as simple and quickly as we can, hence the proposed test.

Markus
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Old Apr 06, 2012, 02:52 PM
Kiwi in Germany
whakahere's Avatar
Germany
Joined Jun 2010
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That is what I have done markus.

here is with no filtering.
http://www.youtube.com/watch?feature...&v=ed7Sbn5kBGc

here with a filter
http://www.youtube.com/watch?&v=PoG_XKnWDcs

here is the filter
All taken from an old computer power supply.
1 - toroid core
1 - 470u 16v cap
1 - 104 ceramic cap
http://static.rcgroups.net/forums/at...7-IMG_0916.jpg
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Old Apr 06, 2012, 03:29 PM
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Switzerland, LU, Buchrain
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Quote:
Originally Posted by whakahere View Post
That is what I have done markus.

here is with no filtering.
http://www.youtube.com/watch?feature...&v=ed7Sbn5kBGc

here with a filter
http://www.youtube.com/watch?&v=PoG_XKnWDcs

here is the filter
All taken from an old computer power supply.
1 - toroid core
1 - 470u 16v cap
1 - 104 ceramic cap
http://static.rcgroups.net/forums/at...7-IMG_0916.jpg
Every DC/DC converter type also has other harmonics and ripple, so what helped in your case might helps in the other, but not necessairly. I currently have my CNC mill running, so I could not hear in your video if you had the motor running (and every bec and motor also behaves differently) or not. To me it looked more like remaining ripple from your DC/DC converter as noise introduced by motors usually looks different (bigger stripes).

Makeing a good clean power train is sometimes not so trivial. As mentioned, the trouble also could be caused by other things, that's why I suggested to reduce the setup to the abolutely necesairy things, then do range tests without motor to see if we face an issue with the HF parts including the antennas cables etc. or if it's power source related. In situations like this you need to exclude causes to get to the bottom of the problem.

Markus
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Old Apr 06, 2012, 03:32 PM
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The guy with the low range uses a two battery setup, so there shouldn't be interferences through the wires, if its not connected to the motor..right.
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Old Apr 06, 2012, 04:08 PM
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Quote:
Originally Posted by msev View Post
The guy with the low range uses a two battery setup, so there shouldn't be interferences through the wires, if its not connected to the motor..right.
It sounded alike, but he uses a UBEC, alas a DC/DC converter to power the HF module (at least that's how I understood), so either ripple and or harmonics caused by that (or other on board components) could have disasterous influence.

I would rip the vtx and camera out, provide a clean 3.3v source and do a ground test. Should give a clear answer. If this works, then add the UBEC and so on up until the source of the problem is found. If it does not work, replace the camear also to exclude that too and so on.

Markus
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Old Apr 06, 2012, 04:18 PM
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SW England
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That's why I use a 'dumb-as-a-rock' 3v3 800mA LDO regulator.
I get no interference on my little 'pod' and no need for complex filtering, just a simple DIY power supply that feeds the VTx and camera from the balance port of the flight battery.

http://www.rcgroups.com/forums/showp...&postcount=790

Just waiting for a nice C-P antenna to arrive

Nigel.
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Old Apr 06, 2012, 05:16 PM
Kiwi in Germany
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Germany
Joined Jun 2010
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when you say you power it off the balance port does that mean you only tap 2 cells?
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Old Apr 07, 2012, 02:14 AM
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SW England
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Quote:
Originally Posted by whakahere View Post
when you say you power it off the balance port does that mean you only tap 2 cells?
Yep, exactly that.

2S lead
http://www.giantcod.co.uk/silicone-c...-p-406533.html

3S lead
http://www.giantcod.co.uk/silicone-c...-p-406534.html

Cut off the male end and then feed whatever voltage(s) you need from the female end to the voltage regulator/pod/camera/VTx.
You could tap it twice, once for the camera and again for the VTx and not bother with the voltage regulator (same as running from a 1S LiPo).

Nigel.
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Old Apr 07, 2012, 03:45 AM
Mmmmmmm!
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Kingdom of Sweden, Dalarna County, Sater
Joined Oct 2011
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Quote:
Originally Posted by markus123456 View Post
As oposed to quix-fz opinion, the antennas make a big difference, but the range you get is catastropic. Asuming you use a 200mW sky-rf setup, you should get 3km for sure with the antennas unless you fly above some very very RF noisy area. Even there you would get way more than 300 - 500 meters. So something must be fundamentially wrong.

The 5.8Ghz setups usually are pretty roubust in terms of other components radiating in or harmonics even thoug this still could be. Are you sure what you observe is not based on an unfiltered noisy power train? Do you use the stock transmitter, or are you useing a HF module alone with some sort of power source? Did you made ground range tests without motor running? How about posting a video?

Markus
Power train? Mine's completely unfiltered and as simple as it gets. I have the F450 frame with the built-in power distribution board, that supplies power to all motors. I also have a JST connector on one pad and that feeds power to the video setup. So one battery is used for everything. I used to have a dedicated 3S Lipo feeding the video Tx (It won't take 2S as far as I know) but removed that to save weight and that setup worked for me at close range, so I never noticed any issues.

Are you saying you have to use a dedicated battery and whatnot? The voltage fluctuations in the main power train is enough to throw off the 5.8ghz equipment? I've heard the thing about some cameras being noisy, mine's right up against the video Tx, here's a pic of the setup, ignore the antenna, I've got yours on it right now. Also, I'm using the Hobbyking 200mw 5.8ghz kit.



Here is my usable range at the moment... Also, it's worth noting that without ANY sort of quad, just holding the receiver and goggles in my hand I got 900m out of my own antennas before I had to turn back because lunchtime was over! So it's the quad for sure, something on it... Also, I wouldn't say this is an area full of interference, there are no towers or buildings nearby, it's just a huge empty area.

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Last edited by WiseDuck; Apr 07, 2012 at 03:57 AM.
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Old Apr 07, 2012, 04:28 AM
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Whaka if you have some extra time on your hands you could make a flight test with that 3.3V ubec, so we'll know if that's the issue or not..

Wiseduck you could try a secondary lipo and add some distance between the cam and the tx, and then tell us if the range is still shabby..
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Old Apr 07, 2012, 04:49 AM
Mmmmmmm!
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Kingdom of Sweden, Dalarna County, Sater
Joined Oct 2011
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Ive got everything on my VC-FPV frame now. I'll maiden it later today and also test the FPV setup with a separate Lipo and whatnot. I'm very close to finishing this thing.
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